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  1. 12 points
    The bacterial brood disease American Foul Brood (AFB) occurs worldwide and leads to significant losses of honey bee colonies every year. In several countries, as in New Zealand, AFB is a notifiable disease and infected bee colonies have to be burned to contain the disease. Although it has been under investigation now for more than a century, the underlying characteristics of the host–pathogen interactions on larval level remain elusive. An effective treatment of AFB does still not exist, partly since the progression of the disease following ingestion of spores has only been described superficially. The bacteria that cause AFB belong to a large group of similar bacteria that can be both extremely useful and highly damaging. In 1988 scientists began to divide the main 'bacillus' classification into smaller, more comparable sub groups based on genetic, phylogenic principles rather than morphology, and one of the initial five sub-groups was 'Paenibacillus'. Literally, 'almost' bacillus. The species known for AFB became Paenibacillus larvae. The continual re-evaluation of the groups has led to the re-naming of some new species and the re-classification of existing species so that the classification continues to grow, and the genus currently has about 200 species. Paenibacillus is still expected to undergo significant taxonomic subdivision as these useful or otherwise relevant Paenibacillus continue to be studied, more are added, and the groups get unreasonably large. Many species of Paenibacillus produce antimicrobial compounds that are useful to fields like medicine, agriculture, industrial chemistry or bioremediation. Another well-known aspect of Paenibacillus is its role in the spoilage of milk and other dairy products, where its enzymes and metabolic products negatively impact the flavour or texture of dairy products, in, for example, the milk curdling caused by proteases. One of the challenges is that Paenibacillus are 'psychrotolerant' spore-forming bacteria. They form hardy spores, and function well at low temperature. Many Paenibacillus strains grow well in refrigerated temperatures used for storing milk. They represent more than 95% of bacteria in raw milk after 10 days of refrigerated shelf life, while spoilage of pasteurized milk due to Paenibacillus is delayed by the germination process of spores and usually occurs after 17–21 days. Paenibacillus species have also been used as pesticides to kill agricultural pests in a variety of ways. The chitinase enzymes they produce hydrolyse chitin, which is a structural polysaccharide of insect exoskeletons and gut linings. Like other bacteria, Paenibacillus species compete with other micro-organisms through the production of a wide range of antimicrobial compounds. All these general properties of Paenibacillus - curdling proteases, cool temperature range, chitin-destroying enzymes, persistent spores, and antimicrobial activity, are apparent in the symptoms produced by honey bee colonies infected by Paenibacillus. For beekeepers, we know AFB is caused by strains of Paenibacillus larvae, each identity named after particular gene sequences known as ERIC (Enterobacterial Repetitive Intergenic Consensus) sequences. ERIC I and II are the types typically isolated from hives; ERIC III and IV are not considered to be significant. ERIC II is the most virulent strain, but ERIC I is more prevalent globally, not just because it can infect all honeybee subspecies, whereas ERIC II has been confined to to certain subspecies, but also because, being less virulent, it is more likely to be found. ERIC II will kill larvae in just 6 to 7 days. This strain produces a unique protein which facilitates attachment of the bacteria to part of the honeybee’s midgut. By contrast, ERIC I takes up to 12 days to kill infected larvae. The earlier larvae die the more effectively they can be removed as part of the social immune response of honey bees. By removing the dead larvae quickly during normal brood hygiene fewer bacterial spores are produced and spread in the hive. As a worker larval stage lasts six days ERIC I strains tend to die as pupae, while ERIC II strains can have deaths in open brood which are easily detected and removed by the bees. In one study only around 5% of ERIC II infected larvae died after cell capping, while 27% of the ERIC I infected larvae died after capping. Reports about the variable behaviour of AFB infections, and of the disappearance of infections in some circumstances, are presumably explained by the different expression of symptoms for each strain, and the variation between different strains and races of honey bee. For example, different species of honeybees produce subtly different royal jelly proteins, and this seems to affect their vulnerability to P. larvae infections. Apis mellifera ligustica’s royal jelly proteins are known to differ from those produced by Apis cerana. Interestingly, this difference in activity may provide Apis mellifera ligustica faster metabolic function and enhanced immune activity, and so the strain is a little more resistant to P.larvae (and A.apis) than is Apis cerana in that larval exposure to the spores results in infection less frequently. This may also help to explain the specificity observed in P. larvae ERIC II infections. Until recently it had been assumed ERIC II was restricted to northern and central Europe, Argentina and Uruguay, but examples have now (2014) been isolated in Canada and New Zealand (Schäfer 2014). Honeybee larvae are most susceptible to infection by the bacteria's spores within the first 36 hours after egg hatching when larvae are fed with accidentally contaminated food. After metamorphosis bees are not susceptible to infection by the spores. As pupa they are not fed, and as adults they are able to void any spores they ingest. Foul brood eventually kills all the colony's offspring so there are no replacement workers to replace aging and dying individuals and the colony will collapse, often succumbing to robbers that spread the infectious spores in the process. Only a few spores are needed to initiate infection, but the number depends on the age, caste, and genetics of each larvae. As a rule, very young larvae are fed with brood food produced by nurse bee head glands, but as they age this food is progressively diluted by adding some of the honey or nectar content regurgitated by the nurses, increasing the risk of contamination. This is mitigated to an extent by the nurse's proventriculus filtering out spores, and with increasing age the larva's gut environment becomes progressively more hostile to the bacteria. By 48 hours after egg hatching most larvae are no longer vulnerable to the bacteria. The phospholipid lysophosphatidylcholine (LPC) has been identified as an antibacterial compound in honeybee midguts in both naturally developed and artificially reared honeybees. The concentration of LPC in royal jelly was below the limit of quantification, which probably indicates that it is not produced from the head glands. On the other hand, feeding experiments using fluorescent-labelled LPC indicate that it is delivered to young larvae with regurgitated honey stomach content to larvae. Fluorescence was found in middle-aged and older larvae to a higher extent than in young larvae, which corroborates that the delivery route via honey stomach becomes increasingly important with larval age. In older larvae and adults, in addition to a fully-formed peritrophic membrane, LPC is present in honeybee midguts, coexisting with the normal gut microbiota, as a permanently active immune trait representing a first line of defence against AFB and other infections. A healthy (lipid-rich) pollen supply is partly responsible for enabling LPC production. Spores that have been ingested germinate rapidly in the midgut of infected larvae. Soon after ingestion vegetative bacteria can be found randomly distributed in the midgut cavity or 'lumen' and proliferate in the following days. Four to five days post infection the guts of larvae can be filled with P. larvae, while no bacteria are detected in the body, the midgut epithelium remains intact, and the 'bolus' containing the bacteria is still contained with the insect's peritrophic membrane, protecting the gut lining. This membrane, common to most insects, begins to form in larvae after about 8 hours and is thought to have evolved from the mucus lining the gut cells. It will in time form a barrier to protect the bees from mechanical abrasion and invasion by micro-organisms. As the bacteria multiply in the gut cavity they release compounds that have antibacterial and antifungal properties that kill any and all other species that might compete in the space. Metabolic fingerprinting (tracing carbon use) of P. larvae has revealed that this bacterium is able to use different sugars and sugar derivatives as a carbon source, so that the larval food and chitin containing larval structures can serve as food during this phase of infection. Both strains use chitinases that will degrade the peritrophic membrane for nourishment and once degraded they have access to the midgut lining. They eventually penetrate the midgut epithelium and migrate through the spaces between the cells into the haemocoel using an extensive arsenal of enzymes that destroy the proteins and collagen that bind the cells together, or bind the cells to extracellular matrices. At this point he host larvae dies and the toxins and enzymes produced continue to destroy and homogenise the body contents. When the larva dies a pure culture of P.larvae is present, a mix of both vegetative bacteria and bacterial spores. While we have always thought that the bacteria begins to form long-lived spores as a response to the immanent consumption of its food supply it is now clear that spore formation begins immediately and continues through the entire infection process. This article is available as a Portable Document (.pdf) here; The bacterial brood disease American Foul Brood.pdf Photographs 1. An infected and normal pupa, cell cap removed, both 13 days old. The infected lava shows no body differentiation or segmentation and gravity makes it slump or ‘melt’ into the bottom of the cell. (Genersch 2010) 2. An advanced infection, with ragged and perforated and ‘wet’ cell caps, ooze through the cap, and scales forming on the cell floor. Note the brown colour of the exposed pupa. (Bee Informed Partnership) 3. Top/bottom row. Fluorescent markers added to the bacteria highlight the bacteria green against the yellow (or red) body parts. In B the large arrow points to a break in the gut wall. The images in the bottom row are of an uninfected larva. (Yue et al 2008) 4. Electron micrograph of a single P.larvae spore. The germ cell of the spore itself starts at position ‘GW’. The outer coats make it extremely resistant to desiccation, direct heat, chemicals, and antibiotics. (de Guzman et al 2011) References and Reading Current knowledge and perspectives of Paenibacillus: a review, (2016) Grady et al. Microbial Cell Factories 15:203 DOI 10.1186/s12934-016-0603-7 Reclassification, genotypes and virulence of Paenibacillus larvae, the etiological agent of American foulbrood in honeybees - a review, (2006) Ainura Ashiralieva, Elke Genersch Apidologie, 37 (4), pp.411-420. Strain and Genotype-Specific Differences in Virulence of Paenibacillus larvae subsp. larvae, a Bacterial Pathogen Causing American Foulbrood Disease in Honeybees, (2005) Elke Genersch, Ainura Ashiralieva, and Ingemar Fries Applied and Environmental Microbiology, Vol. 71, No. 11 p. 7551–7555. doi:10.1128/AEM.71.11.7551–7555.2005 Rapid identification of differentially virulent genotypes of Paenibacillus larvae, the causative organism of American foulbrood of honey bees, by whole cell MALDI-TOF mass spectrometry. (2014) Marc Oliver Schäfer, Elke Genersch, Anne Fünfhaus, Lena Popping, Noreen Formell, Barbara Bettin, Axel Karger. Veterinary Microbiology Volume 170, Issues 3–4, Pages 291-297 https://doi.org/10.1016/j.vetmic.2014.02.006 How to Kill the Honey Bee Larva: Genomic Potential and Virulence Mechanisms of Paenibacillus larvae, (2014) Djukic M, Brzuszkiewicz E, Funfhaus A, Voss J, Gollnow K, et al. PLoS ONE 9(3): e90914. doi:10.1371/journal.pone.0090914 Paenibacillus larvae Chitin-Degrading Protein PlCBP49 Is a Key Virulence Factor in American Foulbrood of Honey Bees, (2014) Garcia-Gonzalez E, Poppinga L, Funfhaus A, Hertlein G, Hedtke K, et al. PLoS Pathog 10(7): e1004284. doi:10.1371/journal.ppat.1004284 Fluorescence in situ hybridization (FISH) analysis of the interactions between honeybee larvae and Paenibacillus larvae, the causative agent of American foulbrood of honeybees (Apis mellifera), (2008) Dominique Yue, Marcel Nordhoff, Lothar H. Wieler, and Elke Genersch. Environmental Microbiology 10(6), 1612–1620 doi:10.1111/j.1462-2920.2008.01579.x Lysophosphatidylcholine acts in the constitutive immune defence against American foulbrood in adult honeybees, (2016) Ulrike Riessberger-Gallé, Javier Hernández-López, Gerald Rechberger, Karl Crailsheim & Wolfgang Schuehly. www.nature.com/scientificreports/ Scientific Reports | 6:30699 | DOI: 10.1038/srep30699. Honey bee age-dependent resistance against American foulbrood (2001) Karl Crailsheim, Ulrike Riessberger-Galle. Apidologie 32 (2001) 91–103 91. Response of in-vitro reared honey bee larvae to various doses of Paenibacillus larvae larvae spores, (1998) Camilla J. Brødsgaard, Wolfgang Ritter, Henrik Hansen Apidologie, 29 (6), pp.569-578. Involvement of secondary metabolites in the pathogenesis of the American foulbrood of honey bees caused by Paenibacillus larvae, (2015) Sebastian Muller, Eva Garcia-Gonzalez, Elke Genersch and Roderich D. Sussmuth The Royal Society of Chemistry Nat. Prod. Rep., 2015, 32, 765. Radiation inactivation of Paenbacillus larvae and sterilization of American Foul Brood (AFB) infected hives using Co-60 gamma rays, (2011) De Guzman, Z.M., et al Applied Radiation and Isotopes, 69 pp1374-1379 doi:10.1016/j.apradiso.2011.05.032 American Foulbrood in honeybees and its causative agent, Paenibacillus larvae, Elke Genersch, (2010) Journal of Invertebrate Pathology Volume 103, Supplement Pages S10-S19
  2. 10 points
    Overcast afternoon. Venturing out to the back yard recovering from a migraine. Over the past month or so I have been feeding a couple of nucleus colonies 1:1 syrup with seaweed extract added. Also 1/3 of a Megabee premade patty. Nucleus 1 has continued to increase the brood area and there is a continuous emerging of new Bees now, and in turn the population is noticeably getting larger to care for the corresponding increase in brood. I added 1 Apivar strip after adding some bees from a queenless colony that had missed the treatment round. A few dead varroa were noted on the floor of the nuc box. Nucleus 2 has been treated the same way. This colony started the process with no brood. The colony is smaller than Nuc 1 however the queen started laying with the addition of 1:1 syrup and later pollen substitute was added. Brood area and newly emerged Bees have seen this colony also noticeably increase in size. Both nucs have brood areas that, when emerged will start to have a significant impact on how the colony functions. They will be getting to a point of criticle mass and will continue to increase in numbers very quickly. looking good so far - Nuc 1 Nuc 2
  3. 9 points
    Have you ever wondered about honey, what it is and why it’s like it is? What about quality and honey, what should beekeepers know? Honey comes from Nectar Nectar is a solution produced by plants that animals collect for food. Plants have special structures that make this solution usually from water and sap flowing in the plant. Often these are found in flowers and attract animals that pollinate the plant, but that is not always the case, and they can sometimes be found on any parts of the plant above the ground. Nor is nectar always there to facilitate pollination. The composition of the solution varies, but mostly it’s a solution of sugars in water, with small amounts of minerals and organic molecules. The nectars we are interested in contain something like 10% to 40% carbohydrates, mainly sugars like sucrose, fructose, and glucose. As well as the sugars the plants produce other chemicals that, for example, help the nectar store, make it attractive to a particular animal, or repel animals that might steal it. Nectar is a very dynamic product. It varies for every type of plant, and for the same type of plant growing in different places. It is presented outside the plant’s tissues, so its properties change with the weather and with time. It is a very expensive product, in terms of energy and raw materials, so it’s highly conserved, even re-absorbed, by the plant. It contains enzymes that gradually change the proportions of sugars in the solution, and these sugars make it hygroscopic. All sorts of animals use nectar as food, from yeasts and bacteria, to insects and birds. Because nectars have such different properties the relationship between the producing plants and the consuming animals can be very specific, but often are not. For example, the consumer may have special mouth parts that specialise in harvesting liquid of a certain viscosity, or it may rely on a solution that contains lots of amino-acids. These relationships can alter as the secretion of nectar changes over time. What is honey? If honey comes from nectar it’s obvious the composition and physical properties of honey originate with nectar, but honey bees alter nectar in two important ways. As they collect the liquid they add a collection of enzymes, (mostly α-glucosidases, generally referred to as ‘invertase’ or ‘sucrase’) that will split a long sugar into small sugars; each sucrose molecule is split in to two sugars, fructose and glucose. They secrete these enzymes from glands in their head as they imbibe the solution, and ‘swallow’ the mixture into their honey stomach (or ‘crop’). During the intake and expulsion of the nectar it’s likely to be contaminated with pollen grains and spores from the environment. An organ in the crop is able to filter some particulates like this out into the bee’s digestive system where they are digested or excreted. After they have transported it back to their hive they regurgitate the liquid and then concentrate it by evaporating water. Whereas nectar is mostly water, honey has four to five times as much sugar as water. By splitting most of the sucrose into smaller sugars the ‘bees end up with a warm (about 34oC) fructose solution that has a lot of glucose dissolved in it, and a little sucrose (1-2%). How this solution behaves when it cools depends on the exact mixture of sugars in it, but as a rule some or all the sugars will not remain liquid and the honey will slowly granulate. The honey will also still contain any of the minerals and organic molecules that were produced in the nectar. The minerals are what gives honey most of its colour, the trace molecules contribute to its flavour, aroma and ‘mouth-feel’. It will now be much ‘thicker’; it has a high viscosity – 200 times that of water, ten times that of an oil. Different densities may have some effect on packaging and container size if sold by weight. Some honeys have such high protein contents they exhibit a property called ‘thixotropy’ and need special handling and packing. As honey it will also absorb water even more quickly that its parent nectar did, which it why ‘bees and beekeepers are careful about exposing it to moist air. And it will contain some (uncertain) quantity of pollen grains and microorganism spores as a result of its natural origin. So honey is concentrated nectar, but honey is a food, defined in law governed by a principle in an international Codex. The Codex alimentarious defines honey too, and if you’re thinking about honey as a commodity, that’s much more important. To paraphrase what the Codex says, “honey is …an unfermented, sweet substance… produced by honey bees from nectar or secretions from living plants… collected… and transformed in honey combs… without objectionable flavours, aromas, or taints absorbed from foreign matter or during storage… or natural plant toxins in an amount hazardous to health.” Honey quality Everything we need to understand about honey quality can be read from the Codex. The first thing is that it is not fermented. If it’s fermented it’s something else, not honey. What prevents honey from spoiling, and fermenting, is its high sugar concentration. As a result, the amount of water in honey is usually regulated by statute. Above 20% water we know honey is likely to ferment, below 17.0% fermentation is not likely. Between those two points the chance of fermentation depends on the count of yeast spores in the honey. This all assumes the honey is homogeneous – the same throughout. If honey has begun to crystalise (we call it granulation) clearly it is no longer homogenous. As honey naturally granulates, the possibility of fermentation increases. If we incorporate air into honey, it is no longer homogeneous and the possibility of fermentation increases. If we leave bits of leaf, pollen and dust, and the odd bee’s leg in the honey it’s not homogeneous (and we add to the bacteria/yeast content). Not only will various sorts of foreign material set up concentration gradients that permit fermentation we increase the chance of there being ‘objectionable taints’ and the like in our honey. Particulates in the honey can also ‘seed’ premature crystal formation leading to early granulation, and it’s common to filter out most or all particulates. The other important part of the Codex is that we should expect honey to be a product of living plants, transformed only by honey bees. It should not contain anything (like chemical pollutants) or be adulterated with products that are not ‘a product of living plants’. It should contain the natural enzymes and biological products that are ‘a product of living plants’, insofar as they are not a hazard to human health. We should not be destroying constituent enzymes by over-heating or processing honey, and in any case, we should be able to tell only honey bees have ‘collected, transformed, and combined’ the nectars to honey. There are many tests in use that can check the integrity of honey, but measuring 5-hydroxymethylfurfural (HMF), one of the main volatile alcohols in any honey, has proved a useful general standard. The compound is produced by sugary solutions at a rate that depends on time and temperature, and the ‘HMF’ quantity has proved to be a good proxy for indicating change in the chemical properties of honey. HMF can tell us whether or to what extent we have ‘transformed’ the honey, and not the ‘bees. Being true to quality It is important to adhere to local legislation about trade descriptions, food labelling, and weights and measures. There may be specific regulations that deal with food safety, (in NZ the Tutin regulations are the prime example) or standards that must be met to conform with export regulations and compliance in local or overseas markets. None of these take anything away from the principles in the Codex. There are also conventions (with varying degrees of ‘authority’) that attempt to define how honey shall be described, especially when trading between countries. For many years honey colour has been described using the ‘Pfund scale’ using a colorimeter, and while there are now more sophisticated spectrophotometric measures the Pfund remains part of the beekeeping vocabulary. Several countries have attempted to standardise the descriptions of the aroma and flavour of honeys using tools like a ‘flavour wheel’ (not New Zealand), and as the interest in ‘varietal’ or ‘gourmet’ honeys has grown these have become widely used to describe and classify the variety of honey available, rather like wine tasting. You can find one you like on the ‘web. Representing the ‘honesty’ of honey is essential in preparing and describing the product. When preparing honey for consumption and sale seemingly small ‘defects’ create doubt about the provenance and preparation process in the mind of the observer. Are those small bubbles from fermentation or sloppy preparation? Why is there sediment at the bottom of the jar and scum on the top? Worldwide, different consumer groups have different attitudes to filtration, clarity, and shelf-life, some more discerning and selective than others. It is also important that descriptions, of any kind, are true. Apple blossom pictured on the label of a jar of pasture honey is misleading would not be permitted in some jurisdictions. Putting a sprig of lavender in your lavender honey may not be smart, but putting it in clover honey can be construed as a lie. As consumers become more discerning your product also characterises how you run your business; “You said it was ‘honey’, not ‘honey with added ‘bee bits’!”. Are the fragments an indication of how roughly you treat your bees, an errant wing an indicator of your insensitive beekeeping? Consumers may regard the possibility of mite treatment residues in the honey you supply as a betrayal. While these details may or may not be part of the regulatory environment, they are part of the ethical framework beekeepers have established over many years. Disregard them at your peril.
  4. 8 points
    A honey bee nest and its enclosure provides a rich and stable range of ecosystems where we might expect an abundance of microbe populations to thrive, constantly replenished through its interface with the phyllosphere that surrounds it. We know a great deal about the harmful micro-organisms that cause disease; foulbrood bacteria, chalkbrood and nosema, even virus infections, but very little about beneficial micro-organisms that maintain health. Despite a contemporary obsession with prophylactic ‘probiotics’ and gut health there is actually not much known about the contribution from microbes to honeybee fitness, and still less about what the effects of antibiotics and fungicides from pollutants or veterinary treatments might be on the microbiotic environment ‘bees share. There are two ‘communities’ of bacteria here that are particularly interesting, that associated with the pollen collected and stored for food, and that inhabiting the ‘bee gut itself. Pollen provides the bulk of proteins, vitamins and lipids for colony growth. It is also a warm, moist and sugar rich source of food, albeit acidic, and arrives with its own collection of microorganisms, some well able to exploit it for their own purpose. While it has always been believed pollen stored as ‘bee-bread’ is a pre-digested store of food (similar to honey) closer study show this is probably not true. We find ‘bees prefer pollen less than three days old, that is, they weren’t waiting for some process (akin to fermentation) to occur before eating it. In addition the bacteria counts from collected pollen were low and declined rather than increased. That’s not what we’d expect if the store was supporting the microbes. The populations were so low that it was implausible there were enough to have any effect; the estimate was one microbe for every 2,500 pollen grains. Using microscopy the mostly intact grains did not appear to have been altered in any way by storage, and the bacteria found did not have the characteristics of a stable microbiome but were adapted for survival in acidic, antimicrobial environments. The bacteria in stored pollen are very different from those in the hind gut where pollen is being digested, and where they are present in hundreds or thousands per grain of pollen. It appears then that stored pollen is in a state for preservation rather than conversion, and that actually the true ‘store’ of nutrients is the ‘bees themselves. We often talk about pollen (fresh or stored) being digested in a ‘communal stomach’. What we mean is that pollen is eaten by a fairly limited group of young bees and fed to everyone else in the colony. These ‘nurse’ bees consume pollen and from glands in their head then secrete a semi-liquid food, This can be pooled in honeycomb cells to feed larvae or shared directly, ‘mouth to mouth’, with the queen and other members of the colony. As nurse bees age and become guard or forager bees they gradually lose the ability to digest pollen and have to be fed by a new generation of nurses. How these ‘bees extract nutrients from pollen grains is not fully understood, but it’s possible microbes play their part. Scanning electron microscope observations of pollen passing through the digestive tract show a range of states, depending on far along the gut you look and, presumably, on the type of pollen grain and its construction. Some are fully ruptured, perhaps because of osmotic shock, others seem more or less intact but empty, the contents removed gradually through the germination pores in the grain. Another interesting line of research has considered the inevitability of bees consuming the yeasts, bacteria, and fungi that naturally associate with pollen (or nectar) and suggest that this would mean bees are actually omnivorous. Using native (solitary) bees and examining isotopes of carbon and nitrogen in the amino acids glutamic acid and phenylalanine that were consumed the research was able to show the bees were assimilating both microbial and plant proteins. In another study they demonstrated a decline in biomass and increased development time in larvae fed a diet progressively increasing in sterilised pollen, indicating the microbes were an essential part of the diet. This is analogous to leaf-cutter ants growing and consuming fungi grown on the leaf substrate they collect, rather than eating the leaves. We talk about the bee ‘gut’ as though it was all one homogenous organ, but in reality it is a series of blended zones or organs each with distinct functions and correspondingly different environments and inhabitants. Looking at the microbes in these ‘zones’ is tricky. Older methods rely on culturing bacteria on a growth media, but it possible to miss or underestimate microbes that are unexpected or difficult to culture. Later methods use PCR amplification and genetic makers, but that too has some limitations so that at the moment the most accurate information comes from studies that use and compare both methods, what’s called culture-dependent and culture-independent methods. Working out where these microbes belong is also tricky, some, not adapted to live in a particular environment, may just be passing though and do not form the stable biofilms bacteria flourish in. Newly emerged ‘bees have no, or only a couple of types, of gut bacteria. ‘Bees acquire bacteria that inhabit their gut from their foraging environment, but also from each other when food is shared. Plainly bacteria in the phyllosphere are present, mostly in the crop, but this is an inhospitable temporary haunt because its contents change so often. It seems unlikely there is a permanent ‘core’ group of bacteria associated with this region, and little evidence for one. The mid-gut and hind-gut do have lasting ‘core’ groups of bacteria and the highest bacterial counts are found here, with most actively growing and reproducing biofilms in the hind gut. The communities have quite different inhabitants from those found in pollen, ‘beebread’ or honey and remain consistent across seasons and geographical regions. When we look closely enough we find that although a gene sequence can indicate a close physiological relationship to other organisms, when it comes to bacteria even closely related species can display remarkable differences in their functional genes. Perhaps surprisingly this simple set of perhaps eight or so core bacteria types are found only amongst eusocial bees, and appear to have diversified to occupy particular niches and perform functions that only apply in groups of honeybees or bumblebees, and that are conserved by their sociality. Long-standing co-evolution has produced functionally unique strains adapted to a symbiotic existence with each other and their bee family, possibly unique even at colony level. L. M. Klungness, Ying-Shin Peng, Scanning electron microscope observations of pollen food bolus in the alimentary canal of honeybees (Apis mellifera L.) Canadian Journal of Zoology, 1984, Vol. 62, No. 7 : pp. 1316-1319 https://doi.org/10.1139/z84-189 Anderson KE, Sheehan TH, Mott BM, Maes P, Snyder L, et al. (2013) Microbial Ecology of the Hive and Pollination Landscape: Bacterial Associates from Floral Nectar, the Alimentary Tract and Stored Food of Honey Bees (Apis mellifera). PLoS ONE 8(12): e83125. doi:10.1371/journal.pone.0083125 Anderson KE, Carroll MJ, Sheehan T, Mott BM, Maes P, Corby-Harris V. 2014 Hive-stored pollen of honey bees: many lines of evidence are consistent with pollen preservation, not nutrient conversion. Mol. Ecol. 23, 5904–5917. (doi:10.1111/mec.12966) Steffan S, Dharampal P, Danforth B, Gaines-Day H, Takizawa Y, Chikaraishi Y. (2019) Omnivory in bees: elevated trophic positions among all major bee families. Am. Nat.vol. 194, no. 3. doi:10.1086/704281 Dharampal PS, Carlson C, Currie CR, Steffan SA. 2019 Pollen-borne microbes shape bee fitness. Proc. R. Soc. B 286: 20182894. http://dx.doi.org/10.1098/rspb.2018.2894 Philipp Engel, Vincent G. Martinson, and Nancy A. Moran Functional diversity within the simple gut microbiota of the honey bee. 11002–11007 PNAS July 3, 2012 vol. 109 no. 27. https://www.pnas.org/content/109/27/11002
  5. 8 points
    Inspection of the nucleus colony today was pivotal in the development of this colony. The queen had all but run out of space to lay. 5 frames had about 80% coverage by attached bees and more out foraging. Rather than potentially stalling the egg laying through having no empty cells To lay in I made the decision to transfer the colony to a 10 frame box. Whilst transfering I placed an empty drawn frame 2 frames in from the internal feeder with the thought of providing a new brood frame for the queen to start laying in. This stimulation process has proved to be effective in growing a small colony over winter and is something I will look to replicate next winter with more colonies. I will keep posting in this blog throughout the season as the colony grows and moves in to honey production.
  6. 8 points
    This article was originally published in 2015 Everybody needs to look over the fence once in a while, especially beekeepers. Something that caught my eye recently was a study looking at weeds and glyphosate resistance, a study which itself took a glance over the palings at antibiotic resistance in hospitals. Resistance is not a phenomenon unique to beekeeping, it is universal and, at its simplest, just about how organisms adapt and evolve in their environment. From our point of view, when we think about resistance, the aspect that concerns us most often is varroa mites not disappearing after we have treated the hive with a substance that usually kills them, and usually we’re talking about the efficacy of the two synthetic pyrethroids used to treat the pest, Apistan and Bayvarol. Pyrethroids have a long history and it was never in doubt that varroa mites would adapt to the treatment. Pyrethroids are copies of naturally occurring esters from Chrysanthemum flowers. What we call pyrethrins were first used as insecticides in the first century in China. They were used in Europe more than 200 years ago and in commercial production by the mid-19th century. Although effective, they were expensive to produce and quickly degraded by light and air, so by 1924 chemists began making ‘synthetic’ copies which were more stable and better suited to one pest or another, or to different ‘delivery systems’. By the 60s and 70s many variants had been produced, including deltamethrin, at the time the most active insecticide ever produced. Apistan and Bayvarol are different pyrethroids, called tau-fluvalinate and flumethrin respectively, which differ in the construction of one end of the molecule. One of life’s ironies (one of my favourites) finds that the ‘natural’ pyrethrins, the synthetic pyrethroids, and the environmentalist’s bête noire, DDT, are all much the same when it comes to their effect on arthropod pests. All of them affect the normal transmission of nerve impulses along the nervous system by stopping the exchange of sodium and potassium ions across an impermeable membrane through a special ‘channel’. (If you’re interested look up ‘voltage gated sodium channels’). What resistant pests have done is to modify the sodium-channel proteins so the insecticide can’t bind to the site. Different pests have modified different proteins, but resistance is extraordinarily common; whitefly, cockroaches, fleas, lice, mosquitos, flies, aphids, thrips, and many others have all evolved resistance to pyrethroids and DDT, to a greater or lesser extent. Known as ‘knockdown’ resistance (knockdown being the excited but paralysed state caused by the nerve disruption) it was first recognised in 1951 in house flies. When we add a treatment to our hives we alter the environment in the hive, hoping that the bees can still flourish but that the things we don’t want die or can’t reproduce. In this sense varroa mites are analogous to the weeds I mentioned at the start. Weeds, and mites, adapt to pesticides in various ways. Besides changing their behaviour (avoiding the chemical for instance) pests can slow or stop the chemical getting into their body, or store it up where it can’t do any damage; they can use enzymes to destroy the active ingredient, or they can change the site or process the chemical is able to disrupt. It’s important to realise these changes come at a cost, sometimes a very high cost, sometimes a very low cost, and rarely, sometimes with an added advantage. For example, a bacteria may construct a thicker ‘skin’, but it will have to use more resources to do so. As long as it faces a threat from the chemical it’s worth doing that, but in an environment where the threat no longer exists if there is extra ‘effort’ involved it’s wasted, and puts the ‘resistant’ organism at a disadvantage compared with an organism that doesn’t bother. For any particular adaption it’s important to understand the cost of that adaption if we want to understand how long-lived and pervasive that adaption will become. Complex, costly changes are easily lost when they are unnecessary; simple, cheap alterations are likely to remain. The science looking at pyrethroid resistant mites has been able to describe in pretty good detail what genes are involved and what they do to allow make mites less sensitive to the chemical. This type of chemical and it’s mode of action is pretty well understood as it been in widespread use for a long time. Around four amino acid substitutions have been proposed in the case of varroa’s pyrethroid resistance. So far, it looks as though the metabolic cost of this adaption to pyrethroids comes at a very low cost for mites, and no differences in ‘fitness’ (for their environment) has been observed between resistant and non-resistant mites. So far, there is very little evidence that regression to a predominately non-resistant strain occurs within a reasonable period of time if pyrethroid treatments are suspended, and that also suggests the cost of carrying the adaption is relatively low. There is not a lot of data about the incidence and spread of resistant mites. Beekeepers aren’t looking for resistance, even though it is simple to do so, and often the only clue is the unexplained loss of treated colonies. Ascribing the cause of the collapse to resistant mites is a long bow to draw however and so usually the cause is hidden by the many plausible reasons for a colony dying. On the large scale however, we do have a picture, and wherever we have looked we can see that the spread of ‘resistance’ replicates the same route that the original mite invasion took; a slow local spread accompanied by an occasional ‘long-distance’ hop. That’s no surprise, mites can’t survive and travel without a bee host, and so the spread of the resistant variety relies on the movement of bees and their colonies, and the same ineffective phytosanitary regimes that permitted the original spread of the pest. It’s also no surprise because that is what happened with other examples of resistance. We will have to wait for more information about the genes involved in providing resistance, but so far it does not look as though it appears spontaneously from multiple origins, it emerges once or twice, by chance, and the mites carrying the attribute spread. Pyrethroid resistant mites have been reported all over Europe, the US, Israel, and parts of S. America. Resistance to coumaphos has been reported in Italy, and resistance to amitraz has been reported in Croatia, France, and the USA. In October 2009, not quite ten years after varroa was first discovered, resistant mites were reported from a hive in Auckland. In the ensuing discussion speculation suggested resistance was likely present in Northland, Waikato, and the Bay of Plenty, and maybe further south. We do not know if the necessary genetic change arose here and was selected by the prevailing pyrethroid use at the time, or whether we managed to import a resistant strain as easily as the original import had occurred. As we don’t know how varroa entered the country it’s possible the ‘gate was never closed’. However it arose, we know it will gradually spread, just as the non-resistant type(s) have. While the available evidence suggest pyrethroid resistance is not widespread amongst varroa mites in New Zealand we have to add the word ‘yet’. Resistance isn’t anyone’s fault, it’s just the way Nature works, and it was not caused by the injudicious use of the chemicals used to control it; the fact is that the clock was always ticking and at some point luck ran out. Inappropriate pesticide use will ‘fix’ the problem in place though. The challenge is to understand its incidence and find the best strategy to manage resistant mites. That’s why I’m interested in looking over the fence. Everywhere we are faced with similar challenges; super-resistant weeds and antibiotic resistant hospital bacteria are two sides of the same coin. The paper studying glyphosate resistance in Ilinois (Evans et al) used a lot of data to look at the outcome of different management practices, broadly, rotating herbicides with different modes of action (MOA) or mixing different herbicides together. These two divergent strategies are also used to manage bacterial resistance to antibiotics in public hospitals, and in both cases the finding is that mixing, not rotation, is the better (but more expensive) strategy. This appears to be true when the fitness cost of a resistant trait is low, in which case the adaption is fixed even in the absence of the selective agent (the pesticide). Mixing strategies are not reliant on the cost of fitness driving depletion. Instead, mixing depletes any resistance alleles by decreasing survival probabilities of all individuals carrying the relevant alleles. It is an expensive strategy as the pesticides for each MOA must be effective. Ineffective, low-dose mixtures can potentially increase the risk of non-target-site resistance and cross-resistance evolution. I can see very little justification for adopting the strategy as a prophylactic treatment; besides the extra cost it only increases the chance of eventually selecting for cross-resistance. In the conclusion the paper points out; ”Herbicide mixtures are not a permanent solution to the problem of target-site resistance; herbicidal mixtures may delay evolution of resistance, but they do not prevent it…long-term, cost-effective, environmentally sound weed management will require truly diversified management practices… Combining chemical, cultural, physical, and biological tactics can provide cost-effective weed management while reducing reliance on herbicides.” For Evans, “We will encounter resistance evolution repeatedly in natural systems managed for human benefit. Sustainable stewardship of these systems will depend on recognising that we are always applying selective pressures, and that management responses need to grow from our understanding of applied evolution” Can’t help feeling there is a lesson for beekeepers in there. Evans, Jeffrey A., et al, (2015) Managing the evolution of herbicide resistance. Pest Manag Sci, (wileyonlinelibrary.com) DOI 10.1002/ps4009 Martin, Stephen, J., (2004) Acaracide (pyrethroid) resistance in Varroa destructor. BeeWorld 85(4): 67-69. Davis, T.G.E., et al (2007) DDT, Pyrethrins, Pyrethroids, and Insect Sodium Channels. IUBMB Life, 59: 151-162. Lagator, Mato et al (2013) Herbicide mixtures at high doses slow the evolution of resistance in Chlamydomonas reinhardii New Phytologist Vol 198(3): 938-945. DOI 10.1111/nph.12195
  7. 7 points
    Everyone knows honeybee females (queens) mate at the beginning of their adult life and are then unable to mate again. A queen mates with many males (drones), often on a single occasion but sometimes after multiple flights in successive days. The mating is very quick, not more than 5 seconds and perhaps no more than one or two seconds, after which the male is paralysed and dies. Competition between males in a mating congregation occurs, mostly as a result of size and power, and some selection operates seemingly on the basis of flight altitude, different strains favouring different heights. A single drone congregation area might contain more than 20,000 drones from potentially hundreds of colonies, and the chance of an individual male being able to mate more than once would be very low. In honeybees therefore it’s not surprising a male expends his entire effort mating with a single queen, and not surprising that probably his best chance of improving his reproductive success is posthumous sperm competition. Queens, at least during mating, appear to have very little ability to choose the paternity of her offspring, but there are good reasons to suppose her interest is in being able to produce a sizeable range of genetic characteristics. Variation is good for managing conflict in a social group, protecting the colony from diseases and environmental change, and providing progressive, adaptable worker performance. Especially in honeybees, as she can never mate again, she has a particular interest in actually opposing or counteracting individual males’ reproductive success, negating sperm competition and choosing diversity. This ‘choice’ is said to be ‘cryptic’, because it is hidden from the male (Eberhard, 1996). Queens are estimated to lay about 200,000 eggs each year; something like 1.0 – 1.6 million fertilised eggs in her 5 – 8 year lifetime. Some hymenoptera (species of ants) do better by a significant margin, producing 8 million workers fertilised by sperm stored for decades. Much more sperm are stored in the spermatheca (in the order of 5 million) than will be needed. Drones will produce between 2 million and 12 million spermatozoa each, and at the end of a mating flight a queen might contain 200 million or so temporarily housed in her oviducts, vagina, and bursa copulatrix. Only around 2.5% of the sperm she acquires during mating is stored, and even less are actually used (think an average two per egg over her lifetime). Spermatozoa can be stored for many years and retain viability. Paternity studies have shown it is completely mixed and used equitably. Discovered in 1905 the key to this remarkable economy of sperm use is something called a Bresslau sperm pump. This structure sits between the spermathecal and the spermathecal duct, a valve in muscular tissue that, if you like, ‘reaches in’ and grabs a constant volume of spermathecal fluid (containing sperm) and transports it out to the eggs. (After mating it ‘pumps’ in the opposite way, filling the spermatheca). While the fluid volume is replaced and always stays the same, the density of spermatozoa it contains gradually declines. The Bresslau sperm pump is also found in ants. With the instruments available nowadays it’s actually possible to count sperm on eggs. Just how bees, wasps and any are able to keep spermatozoa alive for so long eludes a complete explanation, but in short, by an extreme conservation of energy and reduction in oxidative stress. Both seminal fluid and spermathecal fluid must have a role in providing a habitat that nourishing the cells, reduces oxidative stress, and protects them from pathogens, but it’s most likely spermathecal fluid evolved to maximise their long-term viability. Studying spermathecal fluid from virgins and mated queens shows they do differ, but also have some functional similarity with some elements in seminal fluid. Drones too store sperm, although not for as long. In a process that takes at least 40 hours it appears that the storage ‘environment’ is gradually changed from semen to a receptive queen’s spermathecal fluid, to a mated queen’s spermatheca. Spermatozoa in the spermathecal fluid ‘acclimatise’ to their new environment and begin to metabolise very, very slowly, essentially ‘outsourcing’ some of their vital functions to the female environment. In particular, while spermatozoa are able to metabolise aerobically, in storage there is evidence to suggest they switch to anaerobic energy production using a partly metabolised product in spermathecal fluid to limit the release of damaging Reactive Oxygen Species (ROS). As well, the spermatheca is a bead-like organ with two spermathecal glands situated outside a hard sclerotized wall impervious to oxygen. By comparison to other organs the spermatheca has significantly lower oxygen concentrations inside. Spermathecal fluid is also known to contain many highly-active antioxidant enzymes, and these increase if we compare virgins with mated queens. It's become well documented in many species that males don't just transfer spermatozoa during copulation but include a complex mixture of molecules, anti-oxidants, ions and cells other than spermatozoa, including sometimes pathogenic micro-organisms. These male compounds have a variety of functions. Some directly affect the sperm’s survival in the female’s reproductive tract, providing nutrition, pH and osmotic buffering, and defences against oxidizing agents. Other products have important effects on the physiology and behaviour of the female, such as promotion of sperm transport, and inducing ovulation or oviposition. We are now beginning to realise that seminal fluid contains molecules that have a demonstrable effect on gene expression, and that a number of proteins cross the vaginal wall into haemolymph where they can bind to receptors on neurons directly affecting nerve signalling. A somewhat surprising example, consistent with other insect studies and earlier work, establishes a (short-term) loss of visual ability in queens linked to a peptide transferred in male semen. The effect is that queens are less inclined to undertake further mating flights (because they can’t see properly), but with the consequence that the queen tries to fly earlier if she can, before the loss becomes too debilitating. Males have no interest in queens flying to mate with more males. The scientists used RNA-sequencing to look at the changes in gene expression following artificial insemination, comparing them with naturally inseminated queens and queens inseminated with a saline control. They were able to identify the changed genes as ones known to be associated with functions that mostly enable vision. They then carried out a similar exercise, but this time measured the actual performance of the eyes (all of them!), things like their response to different light frequencies, and sensitivity to visual contrast. Last, they used RFID tags to monitor natural flight activity (and queen loss) after the same set of treatments (insemination, mock insemination etc). Each set of experiments indicated that queen’s visual performance deteriorated 24 – 48 hrs after receiving seminal fluid, and they were more likely to be lost on subsequent mating flights. The same effect has been observed in other studies of fruit flies, a parasitoid wasp, and in the bumble bee Bombus terrestris, suggesting that this ability to manipulate female mating using components of seminal fluid could be widespread or even universal amongst Hymenoptera and perhaps all insects. Further reading Boris Baer, Sexual selection in Apis bees. Apidologie 36 (2005) 187–200, INRA/DIB-AGIB/ EDP Sciences. DOI: 10.1051/apido:2005013 Boris Baer, Jason Collins, Kristiina Maalaps & Susanne P. A. den Boer. Sperm use economy of honeybee (Apis mellifera) queens. Ecology and Evolution 2016; 6(9): 2877–2885 doi: 10.1002/ece3.2075 Laura M. Brutscher, Boris Baer, and Elina L. Niño. Putative Drone Copulation Factors Regulating Honey Bee (Apis mellifera) Queen Reproduction and Health: A Review. Insects 2019, 10, 8; doi:10.3390/insects10010008 G Koeniger et al (1988) Assortative mating in a mixed population of European honeybee Apis mellifera ligustica and Apis mellifera carnnica. Insectes Sociaux, Paris Vol36, No2, pp.129-138 Liberti et al. Seminal fluid compromises visual perception in honeybee queens reducing their survival during additional mating flights eLife 2019;8:e45009. DOI: https://doi.org/10.7554/eLife.45009 Boris Baer et al, Insights into female sperm storage from the spermathecal fluid proteome of the honeybee Apis mellifera. Genome Biology 2009, 10:R67 (doi:10.1186/gb-2009-10-6-r67) Ellen Paynter, A. Harvey Millar, Mat Welch, Barbara Baer-Imhoof, Danyang Cao & Boris Baer. Insights into the molecular basis of long-term storage and survival of sperm in the honeybee (Apis mellifera). Scientific Reports, (2017) 7:40236, doi: 10.1038/srep40236 Niño EL, Malka O, Hefetz A, Tarpy DR, Grozinger CM (2013) Chemical Profiles of Two Pheromone Glands Are Deferentially Regulated by Distinct Mating Factors in Honey Bee Queens (Apis mellifera L.). PLoS ONE 8(11): e78637. doi:10.1371/journal.pone.0078637 J. Woyke (1983) Dynamics of Entry of Spermatozoa into the Spermatheca of Instrumentally inseminated Queen Honeybees, Journal of Apicultural Research, 22:3, 150-154, DOI: 10.1080/00218839.1983.11100579 Aldo Poiani, Complexity of seminal fluid: a review. Behav Ecol Sociobiol (2006) 60: 289–310. DOI 10.1007/s00265-006-0178-0 Eberhard, William. (1996) Female Control: Sexual Selection by Cryptic Female Choice. Princeton University Press, ISBN 0-691-01084-6
  8. 7 points
    The number of kiwifruit blocks covered by a canopy is increasing. These canopies consist of a hail netting supported on rammed posts, and can cover a considerable area, thousands of square meters. Many, but not all, are fully enclosed with netting down to ground level along the sides. From a grower's perspective these provide some substantial benefits. Obviously, given the name, one is protection from hail. Even unnoticed hail damage can cause a significant fall in the return a grower gets for their fruit. Another benefit is an almost total reduction in bird damage to buds and fruit, and any waste due to bird lime. The benefit that may have pushed these constructions 'over the line' is PSA protection. While the canopy may increase winter chilling (a good thing!), it certainly does protect the plants from wind damage. Broken shoots are an important point of entry for the bacteria, so this is why full enclosures are becoming more popular. There is an opinion that, having reduced the level of inoculum inside the enclosure, the canopy helps to maintain a phytosanitary environment within. Beekeepers are more reluctant to come onto orchards and place hives these days. Access to an orchard at night (when most hives are delivered) is often problematic, and the current phytosanitary requirements do not make it easy for a beekeeper on a tight schedule operating in the dark. It is getting more common for hives to be delivered to a 'dump' site from which they are distributed by the grower, and for the grower to undertake stimulant feeding. This reduces the amount of foreign traffic in the orchard. Beekeepers are particularly unwilling to enter a canopy, either to deliver or feed hives. But what no one really gave much thought to is how to get the flowers pollinated; at the time; racked with fear about PSA it was perhaps optimistic to think orchardists would figure out honeybees might not fare to well in a cage. In the last three or four years people have realised that pollinating under a canopy isn't, after all, a simple thing, and there is a move to look at how it might be done effectively by resolving the problems honey bees face, or by using some alternative. The optimum placing of hives inside a canopy has not been determined, but may well be different compared with an uncovered block. There are clues that suggest things are not quite the same. There can be a drift of bees from hives in the centre to the hives on the margins near the netting. The distance between male and female vines may be more significant, within a decline in successful pollination with increasing distance from a male, and some anecdotal doubt about effective cross-pollination. With little information about the density of bees, or the density and distribution of males, it’s difficult to know if these are problems that would have existed anyway and are unrelated to an enclosure. It is also difficult to make a judgement about the stocking rates required. Logically, in a confined space without competing forage, less hives per hectare would be assumed. Often large numbers of bees are seen flying at the canopy mesh; those that find a way through are unable to return. A bee’s eyes probably only see a featureless, bright, white plane rather than a barrier, and in a more natural setting bees can fly towards and through bright areas. Some trials of black mesh which apparently lessen the problem probably just relocate it. Bees flying inside the canopy appear to have considerable difficulty relocating their hive, possibly because of the uniformity of the geography within. By far the most serious problem for hives working under cover is bee mortality. In a fully enclosed canopy there is nothing available to sustain large colonies of honeybees. They must be provided with a water source and will have to be fed. A newly delivered pollination unit will have a great need for pollen by design, because we normally want a hive at this stage of growth to maximise the effect it has on pollination. However, it will only contain a few days of pollen reserves (bees do not store large quantities of pollen), and the pollen gathered from the vines in the orchard is poor quality, without the complete set of amino acids the bees require for adequate protein nutrition. Supplementary feeding is possible with manufactured protein supplements and carbohydrates (sugars) but it's important to know these are not replacements for a natural diet. Bee mortality from hives in an enclosure is extremely high. Large numbers of foraging bees may fail to return because of an inability to navigate adequately, and those that do return deliver 'junk food'. A hive starved by both quantity and quality deteriorates very quickly. The loss of bees affects the colony's ability to regulate temperature and care for brood, young bees that normally care for brood begin foraging prematurely, protein deficiency encourages brood cannibalisation, the queen will stop laying eggs that produce new bees, and the hive enters a spiral of decline that takes months to correct. Not only are the hives unsuitable for follow-on pollination work they are incapable of honey production too, effectively rendering them useless for that season. Rather than pollination being priced at a marginal cost, as it is now, a beekeeper would have to attribute the full annual cost of a pollination unit to a 'one-time' use. Honeybees use a variety of strategies to navigate, and are able to communicate (in distinct dialects) distant locations to nest-mates. They have good memories, understand time, and can measure distance. They are able to use the sun as a compass and compensate for its apparent movement across the sky but, as they cannot actually see the sun itself, it’s probably more accurate to think they are using a combination of brightness, size, UV, and light polarization. When the sun is not visible (to a bee) they use the angle of polarised light in the sky, and there is plenty of evidence to suggest they are sensitive to magnetic fields. Bees also have a good memory for landmarks. These have to be substantial given their visual acuity; patterns have to fairly large or really close to be any use, on a geographic scale lines of trees, the shape of the horizon, shorelines, roads, boundaries, buildings and so on. Close up, bees use their eyesight and olfactory clues (scents), and have good pattern recognition, colour vision peaking at the UV, blue and green end of the spectrum, and fast, accurate odour perception. It's quite possible that for much of the time the light transmitted through a canopy does not contain the navigational 'data' that bees need, although there doesn't seem to be any studies to either discount or support this assertion. There is evidence of this in the case of some type of greenhouse. [See Tjeerd Blacquière, Jeannette van der Aa-Furnée, Bram Cornelissen & Jeroen Donders. (2006). Behaviour of honey bees and bumble bees beneath three different greenhouse claddings. Proc.Neth.Entomol.Soc.Meet – Vol. 17]. It is also very likely that an enclosure will limit both the aspect and size of navigational 'landmarks' the bees might use, and the height and angle from which they can be viewed. They have no view of any horizon. In the absence of good spatial information they would need to adopt a more 'route-based' strategy and will be looking for 'close-up' features to use for image matching and as waypoints, and may depend on odour trails. These are fairly easy features to provide, various coloured disks nailed to the top of each post for example, or large graffiti on the canopy! No doubt, aids to navigation are better placed above the canopy than below, and some should be associated with the hive location only. Another thing to consider is whether the current standard for a pollination unit is appropriate for enclosures. Previous trials with honeybees in greenhouses and tunnels suggest it’s probably well worth trying the use of hives that are composed of 'naive' foraging bees, that is, bees that have yet to take their orientation flights. Bees that have already learnt to orient and have to 're-learn' the new location will do so within a pre-existing paradigm, whereas naive bees will learn within the constraints provided by the enclosure. Such hives are fairly simple to provide, but it would be worth experimenting with both queen-right and queen-less versions to understand their foraging capacity, hive density, and so on. There may be advantages combining the use of these hives with dry artificial pollination. Such a system would be comparable to the use of bumblebees, often used in enclosed spaces, but provide greater numbers of foraging bees. Any enclosed hive is going to need dietary supplements for both pollen and nectar, adding to the burden of maintenance and cost. Liquid protein feeds may be particularly suitable in this instance (eg: Megabee). It's not just the cost of feed and labour. Beekeepers have to be careful about feeding hives at this time of year because any food the bees choose not to consume and store instead invariably ends up in the crop produced at the end of the year. In particular, it is easy to contaminate a honey crop with sucrose sugars that render the product unfit for export. Hives that are supplemented may be set aside for pollination use only, limiting their productivity for the beekeeper and potentially increasing the cost to the orchard. The use of small hives that are less demanding of their foraging force may be appropriate, and lessen the problem of ‘overstocking’ the enclosure given the limited forage inside. They may also better control the risk for the beekeeper, and cost for the grower. While growers may think it important to place hives as close to the vines as they can, if a sufficient number of units are used there may be no good reason for distributing bee colonies inside the canopy. In blocks where hives are placed by the edge of the covered area (there are no side panels) perfectly adequate pollination has been achieved for the vines inside. This may not always be the case, but beekeepers are much more likely to favour this kind of arrangement as they are more able to keep control of their asset, and the hives are likely to be self-sustaining. Placing hives at a (say) 10m by 6m opening in the canopy side is possible without creating a wind tunnel (the hive between the opening and a matching 10x6 screen, and at this time the sides are not necessary for excluding birds - buds and soft growth are over, their normal food is available, and no fruit is in the orchard. Alternatively (we don’t know the answer yet), placing hives throughout the area, and particularly in corners, may help to ‘mop up’ lost and drifting foragers, giving them a home even if it isn’t the right home. Are there viable alternatives? Artificial pollination clearly is one, although beyond the scope of the discussion here. However there is no doubt there are high performing orchards where this is the method of choice. There is a current project studying the feasibility of bumble bees as an alternate pollinator (Zespri/Plant & Food). New Zealand is not particularly well-blessed with ‘manageable’ pollinators (that is after all why bees were introduced) but the Bombus bees are worth considering. It’s not clear that the advantages claimed for them apply to kiwifruit, or why in large blocks (rather than greenhouses) they would not suffer from the same navigational issues as their smaller cousins. They are however known for adopting a ‘trap-lining’ strategy when foraging, and this might be an advantage. Perhaps looking at the needs of bumble bees will go some way to re-evaluating the commercial and ecological value of other unmanaged and ‘minimally managed’ pollinators. Not only kiwifruit growers face challenges. Besides the usual seasonal variation that impacts on honeybee survivability, beekeepers already battle the effects of two invaders, the varroa mite and species of Vespid wasp, and there are more to worry about on the horizon. In the autumn wasps, which arrived in the 1940s and 1970s, can completely destroy a honeybee colony in a few hours, and they seem to have a greater impact each year. Since the turn of the century varroa and its associated viruses necessitate a permanent combination of costly management and medicinal measures to keep colonies in good health or they will die. World demand for honey is high, altering the balance between the competing interests of production and pollination in favour of production, while the local demand for pollination is growing as the new gold variety expands. While the market for services will react to the cost and supply of pollination units it is far better to be proactive and anticipate change, rather than cope with its consequences. It's more important than ever that growers think about and plan their pollination requirement well ahead, and that they keep a communication channel open with their beekeeper, particularly when they are considering changes (like covered blocks) to their growing practices. That way beekeepers will be able to adjust the service, technique, and supply to suit the change in circumstances.
  9. 6 points
    Not totally bulging at the seams but definitely growing. This is the 2 frame nuc that I have been feeding protein substitutes and sugar syrup all winter. They finally graduated to a second brood box today. By the End of October I think they will be ready to split and add a mated queen to The queenless half. Bam! doubled a hive count instantly and plenty of time to build up for the summer honey flow.
  10. 6 points
    As Honey bee workers mature they undergo a behavioural development scientists call “temporal polyethism”, more commonly referred to as an age-related (not age-dependant!) division of labour. Younger bees for the first two to three weeks of adult life work inside the hive at tasks such as brood care and hive maintenance, and older individuals work outside the hive as foragers. The transition to foraging involves changes that cause many thousands of alterations in gene activity in the brain affecting metabolism, circadian clocks, hormone activity, and phototaxis. This is largely related to the effects of juvenile hormone (JH), and it seems the gradual increase in JH influences the hive bee to forager bee transition. A honey bee brain has about 950,000 neurons and occupies a volume of about 1 microlitre, tiny compared to the 86,000 million neurons and 1.2 litre capacity of a human brain. Venturing outside the nest creates an instant need to acquire and store information about how to return to it. Foraging is thus cognitively demanding, and besides learning the appearance and location of the hive, new foragers must learn to navigate in the environment and learn to harvest food from different floral types. Given the limits of their cognitive capacity it's not just about what they learn, but what they remember and what they forget. Bees acquire information about the location of their nest-site and food sources in ways that are common to other hymenoptera, including the ones that can't fly! Foraging bees behaving as 'scouts' follow an innate fractal search pattern that is known as a Levy flight. Levy patterns have been found in just about every animal that's been looked at, terrestrial, avian, or aquatic. A Levy search consists of a repeated series of a single long step followed by a cluster of short local steps. This behaviour seems to be deeply buried in the sub-conscious 'psyche' of things that move, almost as fundamental as Brownian motion, a strategy beyond disruption. The orientation fights of the bees and wasps have been recognised for a long time as essential to their 'homing' ability, and for 'fixing' a new food locality they need to return to. The most characteristic feature of this learning episode is the 'turn back and look' (TBL) behaviour. A bee will leave the hive at first almost hovering in reverse, then fly in a series of increasingly long arcs turning to look back and view the hive from the turning point on each arc. Eventually it will circle high above the hive before returning to rest. In doing this bees experience an image of their nest from different angles, seeing it from a distance in the context of the horizon, landmarks, and the sunlight polarized sky. Within a few flights they will be able to recognise the images they have stored and return to it directly. This suite of behaviours will not be repeated for this goal unless the insect has difficulty finding it, in which case it will perform some (shorter) version of the activity to 'refresh' it's memory. The same sequence will occur when it first leaves a food source location. This appears to 'reinforce' the memories it gained on its approach, particularly if the resource turns out to have some significant value. If the resource has little value they won't bother to reinforce their memory of it with TBL. Bumble bees, and to an extent honey bees, are known to communicate and learn foraging behaviours by observing others. Honey bees are famous for learning from each other not just the mechanics of harvesting from a flower but communicating the distant location of the food source itself. This has an immense effect on their respective foraging abilities. Individual bumble bees and solitary bees are masters of the local search and develop very efficient routes (like 'trap-lines') gaining the maximum reward with minimum effort. Honey bees are not efficient in the same way, more often returning to a flower they have just visited for example. However, their ability to recruit nest-mates to exploit the same resource, and the ability to navigate effectively over large distances, ensures efficiency at the colony level. Experiments observing and modelling the results of laboratory work have revealed some of the mechanisms involved in three types of memory-based guidance that bees and other hymenoptera use. Two of these are types of image-matching, sometimes called ‘snapshot memories’, of the surrounding panorama. 'Alignment image-matching' and 'positional image matching' are based on recalling simplified retinal views of its surroundings. Alignment image-matching allows an individual to recall a path that it has previously taken. Positional, unlike alignment, image-matching, can provide guidance from novel locations and in novel directions to match the known image of a goal. The third mechanism is known as 'path integration', by which an insect monitors and stores distance and compass metrics derived from its own movement. They obtain directional information principally from cues deriving from the sun and distance information from monitoring the optic 'flow' of patterns across the eye or sensory input generated by their body movements. Unlike image matching, path integration does not require prior experience of the visual environment. In each case, the insect compares its current sensory experience with a memory of the desired sensory experience to derive a heading that encodes the direction to the goal. While positional image-matching is most reliable in the vicinity of the goal, path integration can be used over large distances. Together, these guidance mechanisms allow bees to forage far from their colonies, and with experience, to embark on, and return from, complicated journeys. While these strategies work together one may be prioritised over the others at any particular time to resolve conflicts or deficiencies, and importantly each can be used train or 'calibrate' the other guidance systems. The emerging consensus from researchers studying hymenoptera is that older hypotheses that invoke 'cognitive maps' as an explanation for successful navigation are unnecessary and do not fully explain observed behaviour. Rather than consulting a map, bees' sense of place might be thought of as constructed from a series of carefully archived photographs. In the last ten years some of the neurological basics of how memories are established and lost are coming to the surface. The 'chemistry' of memory looks to be much the same whichever animal we look at, and given their relative simplicity, economy, and manageability honey bees are often the subject of this branch of scientific enquiry. In simple terms there are three phases of memory. Short Term Memory (STM) has a duration of seconds to minutes and is a feature of the connections made between neurons, of the transient chemical elicitors and receptors that pass signals from sense organs to muscles. Mid Term Memory (MTM), lasting hours, involves a 'cascade' of secondary messenger molecules caused by the repetition of a stimulus. If around for long enough, these secondary messengers eventually produce an enzyme (kinase) which acts on a family of proteins regulating phosphorylation or transcription of genes, creating a Long Term Memory (LTM) that can last days, weeks or more. STM is easily 'contradicted' and decays rapidly. MTM is not reversible, but by not involving protein synthesis needs to be constantly reinforced before it decays. The protein alteration characterising LTM is relatively fixed, causing a structural shape or biochemical change in the animal's proteins, but subject to decay, modification, and not necessarily permanent. In a remarkable study in 2010 Jill Dolowich (remarkable because she was 16 at the time!) was able to show with respect to route and landmark learning that without regular reinforcement LTM is lost within 6 - 9 days. There is also a complex relationship between memory acquisition and extinction with physiological age. Older foragers are often more likely to show evidence of the progressive loss of some types of brain function, particularly spatial memory. On the other hand younger foragers (like bumble bees) are thought to have a shorter memory, which turns out to be a good thing. Forgetting what they knew yesterday encourages them to try new locations and food sources and so builds the experience they don't have. This might be particularly useful for bumble bees that forage on much more transient flora. Honey bee memory is not simply a recording device, absorbing all experience. By staging memory acquisition in this way (and it is a little more complex than outlined above!) there is a sort of 'triage' operating on what will be remembered and what will be forgotten. Together with the behavioural response to 'forgetting' or 'not knowing' (for example - more repetition) bees are able to adjust their investment learning to suit changes in the need for information, or changes in the provision of information by their environment. Memory is constantly but dynamically accumulating or diminishing. How animals retrieve stored memories still eludes us. Behavioural studies suggest that particular sets of memories might be 'activated' by associating them with a motivational state, a goal, or some relevant cue. For example, an insect will recall different memories depending on whether it is seeking food, or has gathered food. As its goal changes the image maps it has associated with its goals are exchanged for the more pertinent set of memories. A bee with a full crop of nectar heads for home if we move it to an unexpected site; if the crop is empty it heads off towards a feeding station. We seldom really appreciate that a crucial factor in the process of remembering some piece of information is context. We ought to know that from our own experience of struggling to name a familiar acquaintance encountered in a novel place! An example of one such memory cue can be scent, in nature perhaps provided by another forager after a recruitment dance. Training exercises with honey bees can accustom them to a scent in a sugar solution, and to different scents in two solutions each at separate sites distant from the hive. It is then possible to use scent alone to stimulate the foragers to leave the hive and visit a feeder even when it is empty. More intriguingly, they will go to one feeder site or another depending on which scent is blown into the hive, apparently associating the right scent with the correct site and recalling the appropriate set and sequence of 'images' for the journey. Landmarks are another plausible cue. Given the right motivation, a displaced ('lost') bee can recall the correct set of 'homeward' images after an accidental encounter with a familiar landmark. Also referred to as 'beacons' these features can be used to 'punctuate' a journey breaking it up into short memorable portions and cueing the appropriate recall. Bees that have swarmed to a new nest site do not simply forget the position of the old site. For a while, given the right motivation (like a lost queen) Worker bees can easily recall the right set of memories and travel back to the original site. In the opposite case Beekeepers moving a hive know to move it sufficiently far away so that a flying bee's experience is completely different, or they try to force re-orientation by blocking the entrance with leafy, twigs, a mirror, or some other device. By doing this foragers should realise landscape or image cues they are accustomed to using to recall the next appropriate guidance memories need to be revised. It is sometimes possible, given weather conditions that prevent the bees from flying, that their memory fades enough that they will need to re-orient themselves anyway. Hence the old beekeeper's rule of thumb for moving hives; three feet, three miles, or three days. Honey bees have a robust system for navigating their environment. Their 'dead-reckoning', supported by celestial clues (path integration'), may be their primary source of guidance in distant novel landscapes, but it has been clearly demonstrated that using panoramic views of the skyline (image matching) is a significant (perhaps the most significant) strategy bees (and ants) use for finding their way around in landscapes they have some knowledge of. In orientation flights and when moving hives bees have been observed quickly spiralling upwards to 20-30m, presumably to gain an unencumbered view of the horizon. When navigational clues from the sky (the sun and polarised light) are absent or confusing bees use their memory of the sun's position with respect to the horizon and time of day, and if they can't see the horizon they make the best guess they can. Guidance from path integration becomes weaker as the goal is approached so that travel along routes tends to reflect route image memories more. As the insects move more precise or reliable cues have more successful outcomes. With increasing experience accuracy emerges automatically as information from the various strategies is evaluated and refined, so it's clear that memory is a crucial part of the system. While it makes the job of scientists trying to untangle and understand what goes on really complicated, by integrating these three components into a single, scalable, 'always-on' system honey bees are ready for anything Nature throws at them.
  11. 5 points
    Colony is still expanding. Brood area is increasing significantly. Still shot gun pattern although every cell has either a pupae, larvae or egg in it. Some dodgy cappings but all inspection of larvae, pupae come up negative for AFB. If the laying pattern doesn’t improve by October this queen will be culled and replaced with a new season queen. Which is a shame as the current queen is an April 2018 mated queen.
  12. 5 points
    Just to show progress. Today I had a quick peak under the lid, now close to 5 frames covered. Photos show 7th June and 5th August. Heading in the right direction.
  13. 5 points
    Nucs are going OK with 1-1 1/2 frames of brood and some older brood starting to emerge. Today I topped up syrup and added another 1/2 of a MegaBee pattie. Brood area is increasing in all the hives. Nuc #1 has some dodgy looking capping so I have inspected those and a few more cells. All is OK so far but I will remain alert the this in future inspections.
  14. 5 points
    OK so a quick look in the nucs today. Overcast grey skies but relatively warm so lots of bees were out flying and good amounts of pollen on the returning bees. Colours ranged from vivid orange, yellow and a small amount of white. Todays task was to add about 500ml - 1 litre of 1:1 syrup to each nuc feeder and have a look to see if brood rearing has increased. Both nucs are chomping through the Megabee pattie and all the syrup add last week has on the whole been consumed with a small amount evident as freshly stored syrup in the empty comb. #1 nuc has gone through nearly half of the pattie and the other nuc which has a smaller population is consuming it from underneath between the frames. Surface area of brood in #1 nuc has doubled since last inspection. Nice fat larvae lying in plenty of feed. Fresh eggs obvious in cells as well. Even saw a fairly young Drone, perhaps with sufficient food available they are willing to care for a Drone or two. Nuc #2 although it is a smaller population has suprised me with a brood area nearly quadrupled since last inspection. Lots of eggs and larvae ranging from 3 days to a week old. Pretty pleased with how how this is tracking. Stimulating the queens to start laying more seems to have been a success, now we just need to maintain it.
  15. 5 points
    It’s 8.58pm and I am sitting by the fire. To date I have added a pollen patty to all of the 5 frame nucs and fed them copious amounts of syrup to get at least 3 frames of feed in the boxes. So far this has worked. There are a few 3 frame nucs that are house in 3 way boxes. They, apart from only 3 frames of bees are looking happy and the combined warmth from sharing a common hive body seems to be helping them. Each of these 3 way nucs has a 500ml container sitting above on the hive mat. This feeds each colony over a week or two. I will be keeping a close eye on them and look to move them in to 5 frame boxes closer to spring. Plans are to take pics of the colonies where possible. I will probably focus on 1 or 2 for the photos to show progress or lack of progress where applicable.
  16. 5 points
    Hives Went through the hive with the old (failing) queen and the new prolific one. The queens are separated with a QE so I know what's happening with each one. Hive is doing really well in terms of numbers of bees & brood. In the failing queen FD, the bees had made a supersedure cell from one of the playcups - it had been capped during the week. No swarm cells anywhere - just the one supersedure. My guess is that the nurse bees in that part of the hive couldn't smell the better queen up the top and decided to requeen. It would be a shame to let a perfectly good looking queen cell go to waste, so I split the old failing queen into a new single FD, together with a few frames of brood & bees including the supersedure cell and some stores. I hope the new virgin queen will get mated and replace the old failing one. Plenty of drones in my hive, so I assume others in the area have them too. This also gave the strong queen more laying space, which she was starting to run low on at the top. I moved her brood nest to the bottom, lifted some frames up and checkerboarded a second FD with stores and foundation frames. The split has obviously weakened the hive a bit just before honey flow and there weren't a lot of stores: I'm feeding 1:1 syrup to both the split and the hive to make sure the bees don't starve and that they have the feed they need to draw out the foundation frames. Hopefully they draw these frames reasonably quickly so I can add supers soon. The other hive is doing very well with good bee numbers (although not as high as with the 2-queen hive) and heaps of fresh stores, no signs of swarm cells. Varroa strips are coming out next week and then it'll be super time. Gear & maintenance I got a couple of extra FD boxes just in case they are needed and slapped some primer sealer on. I'll paint them later in the week and swap them with the current boxes so they can come out for a bit of maintenance. Last season I was in a rush and got some of those thermowood boxes that supposedly don't need paint...but they are already showing signs of cracking, so I'm not that impressed with those. I'll give them a scrape and a lick of paint and hopefully they'll last a bit better. It would be ideal to have a paraffin dipper of course but that would be overkill for my tiny operation - might find out if ABC has one I could use. The hive lid designs seem to both be compromises one way or the other. I started with the closed ends lids but they aren't very easy to get on and off after a season of weather so I bought a sprung end lid and have preferred that in terms of ease of use. I got sprung end lids for the father-in-law but now after the winter he is saying they were letting in water on the hive mat. Who knows, didn't happen to me. I need to start thinking about which kind of honey extractor to buy. It would be nice to just uncap the frames and spin rather than making the bees redraw all those supers every year. It's not a small investment though, even as a shared purchase. A spoon is pretty cheap in comparison.
  17. 4 points
    Physics provides a lens that focuses on our honeybee colonies in interesting new ways and a recent paper from Derek Mitchell at Leeds University’s School of Mechanical Engineering does just that. The mathematics is a bit challenging if you’re anything like me, but it’s possible to get through that, and he also has some worthwhile observations we can apply to polystyrene hives. Mitchell’s current interest (Computational Fluid Dynamics (CFD); his thesis was about differences in heat transfer between natural and man-made honeybee nests using CFD) also has something useful to say about that beekeeping perennial, top vs bottom entrances. This is not the first application of CFD to beekeeping, the Forum has a discussion from a couple of years back about polystyrene hives, and Cory Thompson (with others) studied airflow in Langstroth hives using the method. The results are always interesting, but as important are the assumptions, simplifications and limitations used when devising a workable model. Honeybees harvest nectar to provide a source of a carbohydrate solution in periods of dearth, typically in the winter, but also during drought periods when flowers may not produce any. In order to store this food effectively they concentrate it to reduce the space it occupies and to prevent spoilage. This concentration is accomplished by doing two things. By adding the enzyme invertase the nominally sucrose nectar is converted to contain smaller sugars, mainly fructose and glucose. Fructose is much more soluble in water (even hygroscopic) and not easy to crystalise; a saturated solution of each of the three sugars (at 25C) will contain 81% fructose, 51% glucose, and 67% sucrose. In addition, a solution containing more than 60% fructose can contain much more glucose than a more dilute fructose solution. In almost all cases honey is a super-saturated fructose solution containing glucose. The other thing done to concentrate the volume is to remove most of the water. Typically nectar containing perhaps 80% water is reduced to honey, containing less than 20% water, by evaporation. Any change of state, in this case the liquid to gas transition, requires energy. We call this energy ‘latent heat’; the temperature of the body (the solution, the water) remains constant but the added energy changes its volume, from a fluid to a loosely packed gas of excited molecules. To find out how much energy we can just look it up on Wikipedia J, for water it is 2,260kJ/kg (depending on temperature and pressure). This is actually quite a lot, and even more if you think about the quantity of water involved. A colony could evaporate more than 400kg of water in a year, using almost one gigajoule of energy, or nearly 300 kilowatt-hours. Thirty litres of petrol to you. So where does all that energy come from? A little might come from the warmth of the sun, (and a tiny bit from the invertase chemistry), but given that the ‘bees operate in an enclosed, shaded wooden tree or box a more plausible answer, especially if you can visualise what the ‘bees actually do, is that it is metabolic energy, and it comes from the food itself – nectar. Besides all the other things honeybees do with the energy they harvest; fly, dance, grow, brood, even, waste it, evaporating water might be a very significant one. It’s reasonable to argue that the survival of the colony depends on the efficiency (energy efficiency) of foraging (the colony must gather more energy that it expends or it dies) but we don’t tend to think about the cost (in energy) of storing and making that food energy available. It must be said that the people and (biological) disciplines that study honeybees aren’t experts in physics or engineering, and may not be the best people to think about things like energy or materials. In this study, as a starting point, Mitchell considers the model system to be bounded by the nest enclosure, which constantly loses heat to its environs, and the journey to and from the flower patch where the nectar source is at a fixed distance. The nest enclosure does not change (the hive isn't 'supered'). It excludes the honeybee time spent in flower to flower transport energy (which is assumed to be replaced in the flower patch) and flower nectar depletion or dilution. For the sake of simplicity there is assumed to be no variation in energy consumed due to in-flight changes in insect weight or wind speed, nor does it consider significant activities for the honeybees like water and pollen collection or the nest consumption of honey to fuel brood rearing. The model focuses on the Thermal Energy Efficiency (TEE) as determined by the honey ripening rate, nectar concentration, ambient temperature, airflow inside and outside and any behaviour that controls it, and the thermal conductance of the nest (heat lost). It shows the energy used for nectar conversion is significant, from 20% to 60% of the total energy recovered by nectar foraging. Typical values show that over 50% of the delivered energy may be used in the process of honey ripening and even in exceptionally favourable circumstances for temperate climates, do not use less than 25%. The energy consumption of nectar desiccation limits the maximum foraging distance of honeybees and also changes the energy return for a given nectar source, as well as which nectar sources are viable. The TEE limits nectar conversion so that honeybees can profitably retrieve and refine nectar from either a weaker nectar source or from a greater distance, but not both. A colony that collects nectar at distances, concentrations and TEE outside the break-even line will not add to its honey reserves and may not survive. That much is supported by observations in other studies. As well, improvements in TEE would require less nectar, so less foraging flights, less fanning, and less wing wear. If you're looking for a 'take-away message', Mitchell is suggesting that thermal conductance of hives, previously thought to be only a consideration for winter, has been shown to be a major factor during the nectar collecting periods of the year, and consequently beekeepers should improve thermal efficiency by changing their hives to ones which lose less heat, and facilitating honeybee behaviours that have the same goal, for example, only using bottom entrances. Mitchell D. (2019) Thermal efficiency extends distance and variety for honeybee foragers: analysis of the energetics of nectar collection and desiccation by Apis mellifera. J. R. Soc. Interface 16: 20180879. http://dx.doi.org/10.1098/rsif.2018.0879 Mitchell, D. (2017) Honey bee engineering: Top ventilation and top entrances. American Bee Journal, 157 (8). pp. 887-889. ISSN 0002-7626 EPS vs Wooden Boxes (2017), https://www.nzbees.net/forums/topic/8664-eps-vs-wooden-boxes/ Sudarsan R, Thompson C, Kevan PG, Eberl HJ. (2012) Flow currents and ventilation in Langstroth beehives due to brood thermoregulation efforts of honeybees. J Theor Biol. 1;295:168-93. doi: 10.1016/j.jtbi.2011.11.007. Epub Nov 25 2011.
  18. 4 points
    1. Introduction 2. Venom Biochemistry 3. Minimising the dose 4. Treating the sting 5. Topical treatments 6. Systemic, toxic, and anaphylactic responses 7. Ocular stings 8. Beekeepers 9. Caring for others 10. References Introduction New Zealand is fortunate to have very few stinging insects. These are members of the hymenoptera in which the ovipositor has been modified into a sting delivering venom and are known collectively as Aculeata. There are 29 native solitary hunting wasps, most of which hunt spiders as food for their offspring and are not known to be aggressive towards people. The native solitary bees amount to 18 species of Leioproctus, seven Hylaeus species and four species of Lasioglossum. All these solitary insects, evolved to use their venom in small amounts for subduing other insects, (not mammals) or in a limited defensive effort. It is the introduced social species from the Aculeata that are mainly responsible for stings to humans. These insects manage a communal defensive effort directed specifically at mammalian predators (like people) and so employ toxins and strategies that are effective against mammals, sometimes fatally so. These introduced animals include four species of wasp, a similar variety of bumblebees, and the honeybee. The honeybee is unique in that an individual can only sting once, and then dies. A wasp or a bumblebee is able to sting repeatedly. All of them defend their nest sites by deploying many individuals to attack the aggressor. Insect repellants (like DEET) are not effective on hymenoptera. The incidence of stings varies with your location and the season. Wasps’ stings are the most numerous, particularly in the late autumn when they actively hunt at picnics and barbeques, dive into soft drink tins, rubbish, and consume the sweet saps from garden plants and trees. Honeybee stings are less numerous and more common in the spring, but it depends on the setting (urban, rural, orchards etc). Bumblebee stings are infrequent, often in mid to late summer when the nests are disturbed as a result of being bigger and more obvious, or because it’s a ‘tidy-up’ time for people and their gardens. The reporting of incidents leaves a little to be desired. Fortunately wingless wasps that look like ants don’t figure in the statistics. Most people are unable to tell a ‘wasp’ from a ‘bee’. A few can identify a bumblebee (there are several kinds), and only the most studious could distinguish a ‘paper wasp’ (either of them) from one of the vespulae. Many claim not to have seen what ‘bit’ them in any case. In some respects the venoms from the three are very similar, and how an individual will react, or needs to be treated, can also very similar. An allergic response to one can mean the individual will be allergic to the others. However, it’s not a rule; there are also significant differences between them. Honeybee (Apidae: Apis) venom has been collected for centuries and is consequently the most studied. Mellitin, Apamin, and a peptide that degranulates mast cells are unique to honeybee venom. Wasp (Vespidae/Polistinae) venom contains different phospholipases, and a unique antigen. Bumblebee (Apidae: Bombus) venom is different from both of these, but has some similarity. Consequently there are separate preparations available for testing hypersensitivity or desensitizing. Almost all reactions to stings are allergic responses, even though we don’t commonly use the phrase. Venom biochemistry Bee venom is a blend of components including two peptides, several acids, histamine, dopamine, noradrenaline, tryptophan, sulphur, some minerals,oils, and enzymes. Fifty percent of the dry weight of honey bee venom is mellitin. Mellitin is a chemical that is unique to bee venom and is cytolytic, which means that it bursts cells (the little red ‘dot’ at the sting site is burst red blood cells). Mellitin also dilates blood vessels, leading to low blood pressure. Twelve percent of honey bee venom is Phospholipase A2 (the most potent allergen). Phospholipases are enzymes that help mellitin destroy cell membranes. Apamin is also unique to bee venom (3%) and is a neurotoxin. Hyaluronidase (2%) is an enzyme that breaks down hyaluronic acid, which is one of the components of the tissue in between your cells that hold them together. Hyaluronidase contributes to the “spread” of the reaction. Mast cell degranulating peptides cause the special ‘mast’ cells in your body (part of your immune response system) to release the many biochemicals (including more histamine) in their granules. Histamine causes ‘leaky’ capillaries and contributes to the slightly raised red area that itches in sensitive individuals. In wasp venom the major unique components are phospholipase A1 and B, antigen5, acetylcholine, and serotonin. Many of these proteins are also recognized as foreign by the human immune system (antigens) and lead to a response from the body’s immune system. The ‘first responders’ are the lymphocytes. Lymphocytes come in different types. Their surfaces recognize things that belong and things that don’t and they respond in two ways to things that don’t. They will release antibodies which ‘label’ the foreign matter so that some action can be taken against it, and they will produce more lymphocytes which are there as a form of ‘memory’ of the event. A ‘normal’ response produces immunoglobulinG (IgG); an allergic response produces ImmunoglobulinE (IgE).The mast cells too play an early role. Mast cells are covered in immunoglobulinE antibodies and come ‘pre-loaded’ with histamine, serotonin, protein-destroying enzymes, the anticoagulant heparin, and slow acting leukotrienes, prostoglandins, and cytokines. In response to IgE mask cells disintegrate, liberating their contents. People all produce different amounts of IgG or IgE in response to different ‘invaders’, and what the antibodies ‘recruite’ to aid their effort varies between individuals, so the range of response is very different and depends on the venom, the dose, the site, the individual’s physiology, and even their psychological state. The venom from a sting therefore has a direct physical effect on surrounding tissue, but also causes a response in the body that may or may not magnify that effect. For example, the venom itself will destroy mast cells and release their contents to have a local effect, but the body’s immune system can also start to produce immunoglobulins that will degranulate mast cells remote from the venom site and create a system-wide (systemic) effect. The table below shows the range of possible reactions to a sting. Reactions Reacting Immunoglobulins Onset Times Clinical Manifestations Local IgG 4-48 hours Painful, pruritic, & oedematous sting lesions, 2.5-10cm in diameter. Systemic IgE 12-24 hours Headache, fever, nausea, vomiting, diarrhea. Toxic IgE ½-1 hour Systemic symptoms, syncope, seizures, hemolysis, rhabdomyolysis, acute tubular necrosis with renal failure. Allergic IgG 12-24 hours Initial wheal & flare response at sting sites, followed by painful, pruritic indurated lesions. Anaphylactic IgE 10-20 min up to 72 hours Generalized urticaria, angioedema, dysnpea, bronchospasm, inspiratory stridor, wheezing, chills, fever, apnea, respiratory failure, hypotension, cardiovascular collapse, rarely disseminated intravascular coagulation. Delayed (Apis only) IgG 2-14 days Headache, malaise, low-grade fever, generalized lymphadenopathy, polyarthralgias, serum sickness & thrombotic hrombocytopenic purpura possible, rarely peripheral neuropathy. (After Diaz, 2007.) Minimising the dose There is a basic difference between honeybee stings and the others in terms of the construction of the ‘apparatus’. A wasp or bumblebee’s stinger has no barbs. This means that the insect can withdraw her stinger, and is able to sting again. In contrast, a honeybee can not withdraw her sting. The sting consists of two barbed lancets and a stylet, and the venom gland discharges into a space in between the lancets and stylet, and venom can only travel down this shaft as movement in the opposite direction is prevented by valves. The venom sac has no musculature; the muscle associated with the sting is attached to plates which drive each lancet in turn forward with respect to the stylet, the stylet supporting each using a sort of ‘monorail’ connection. Once the sting has become caught in the skin the bee can’t escape without it becoming dislodged from her body, and as that happens, the Dufour and Koschevnikov glands are torn out and remain with the trapped sting. The later gland produces isopentyl acetate, the ‘banana’ scented pheromone beekeepers are familiar with. This marks the site and stimulates other bees to sting. The lancets meanwhile, are driving themselves, one by one, deeper into the skin and continue to dispense venom. Do not overlook the fact that the most important response to stings from wasps or bees defending their nests should be to get away from the vicinity of the nest. Getting to safety is more important than removing stings immediately, but stings should removed as soon as possible once a person is away from the area. The method of removal does not affect the quantity of venom received by the subject. Much of the advice commonly given regarding the immediate treatment of bee stings derives from a misunderstanding of the structure of honey bee stings. Conventional wisdom says to scrape bee stingers away from the skin because pinching the venom sack could push extra venom into the victim. In fact, how fast you get the stinger out is much more important than how, and in a small number of cases, the scrape treatment results in breaking the sting lancets from the rest of the sting, with the lancets remaining in the subject’s flesh. The method of removal is irrelevant, but even slight delays in removal caused by concerns over performing it correctly (or getting out a knife blade or credit card) are likely to increase the dose of venom received. The advice is to simply emphasize that the sting should be removed, and as quickly as possible, within a couple of seconds. A fingernail is the most convenient tool; just scrape or flick the sting away. If you think you can get your credit card out that quickly, ‘lets do lunch’. The exception to this advice is in the case of a sting to the eyeball or eyelids. A sting to the eyeball should only be removed using microscopy, by an expert; and sting to the eyelid can be removed but must be examined in the same way to ensure remnants do not damage the eye’s surface. If the sting is followed by severe symptoms, or if it occurs on the neck or mouth, seek medical attention immediately because swelling in these areas of the body can cause suffocation. Stings directly into blood vessels can cause a very rapid cardiopulmonary escalation and systemic response. Occasionally, someone can be stung many times before being able to get away. Depending on the number of stings, the person may just hurt a lot, feel a little sick, or feel very sick. Humans can be killed if stung enough times in a single incident. With honey bees the toxic dose (LD50) of the venom is estimated to be 19 stings per kilo of body weight. Obviously, children are at a greater risk than are adults. In fact, an otherwise healthy adult would have to be stung over 1,000 times to be in risk of death, but half that can make you very sick. Most deaths caused by multiple stings have occurred in victims who were known to have poor cardiopulmonary function. A second, potentially life-threatening result of multiple stings occurs days after the incident. Proteins in the venom act as enzymes: one dissolves the ‘cement’ that holds body cells together, while another perforates the walls of cells. This damage liberates tiny tissue debris that would normally be eliminated through the kidneys. If too much debris accumulates too quickly, the kidneys become ‘clogged’ and the patient is in danger of dying from kidney failure. It is important for people who have received many stings in one event to discuss this secondary effect with their doctors. (Wasp stings are as potent in this respect as bee stings.) Patients should be monitored for a week or two following an incident involving multiple stings to be certain that no secondary health problems arise. Treating the sting Most reactions are local and confined to the general area of the sting with pain and a swollen itch, but over 24 – 48 hours they can develop into a much larger area (sometimes the entire extremity. A few hours after the sting more redness, oedema (swelling), and itching develop. Over 12 – 48 hours, the area can become quite swollen, painful, and may also have some associated bruising. The swelling generally begins to resolve after two days, but the site may remain tender (and continue to itch) for a few more days. The total reaction lasts 4 – 7 days. Large locals around the face and mouth or on the hands may cause temporary disability. The large local is IgE-mediated, and therefore is an allergic response. Treatment of local reactions includes ice and elevation with non-aspirin containing analgesics (Ibuprofen), both H1 and H2-receptor blocking antihistamines (diphenhydramine, (Benadryl), famotidine, ranitidine, and non-sedating ones, such as fexofenadine (Allegra), loratidine (Claritin), and ceterizine (Zyrtec), and, occasionally, systemic corticosteroids, such as methylprednisolone, or prednisone, in doses tapered over 2-3 days. Aspirin-containing analgesics should be avoided because both bee and wasp stings may be complicated by local subcutaneous hemorrhage. Taking anti-histamine or a leukotriene-receptor antagonist very soon after the sting may decrease the late phase reaction. Leukotriene-receptor antagonists’ montelukast (Singulair) and zafirlukast (Accolate) block the leukotriene receptors on mast cells and eosinophils and both have peak activity 3 – 4 hours after taking them. In one study of six allergic beekeepers, the skin within their large local reaction and their blood and urine were analyzed 2 hours after a bee sting. Three of them had high histamine levels and the other three had high leukotriene levels, suggesting that allergic beekeepers either have high histamine release or increased leukotriene production, but not both. This implies that about half of beekeepers who have large local reactions might benefit from the immediate administration of a leukotriene inhibitor, whereas the other half would benefit from anti-histamines before or very soon after the sting Oral steroids are useful in treating large locals to stings around the face and hands. The small blisters sometimes formed on the sting wound should be left alone. It is possible to infect the wound if bits of the sting shaft remain or if adequate cleanliness is not observed. Topical treatments Many local and traditional remedies have been recommended for initial management of local hymenopteran stings including the topical applications of tobacco poultices, vinegar, baking soda and salt, aluminum sulfate, and papain, or meat tenderizer. As a rule the clinical activity of all topical treatments for hymenopteran stings (other than ice) is poor, or absent. The more popular ones include; Antihistamines. Histamine is one of the main mediators of the inflammatory response so treatment with antihistamines is indicated. Several topical products containing antihistamines are available for treating the pain, itching and inflammation caused by bites and stings. However, topical antihistamines have been criticized as not being very effective. They are also liable to cause sensitisation so should not be used more often than two or three times a day for up to three days. Oral antihistamines are more likely than topical preparations to bring sustained and effective relief. Hydrocortisone. This has anti-inflammatory activity and hydrocortisone cream is available for treating itching caused by insect bites. However, its usefulness is limited by the directive to limit use to two applications daily, as more frequent application may be necessary to sustain relief. It is not appropriate for use in children under 10 years of age. Once again, oral administration of a corticosteroid, say, prednisone (by prescription), is a more effective treatment. Calamine and zinc oxide. Calamine is made from zinc carbonate with ferric oxide, which is what gives it the characteristic pink colour. It is mildly astringent and its soothing anti-itching action is due to the large surface area and porous nature of its particles, which promote the evaporation of water to cool the skin. Calamine Lotion BP also contains 0.5 per cent phenol which has a local anesthetic action. Calamine has been used for generations for treating hives and itching from many causes, including insect bites. It is cheap and there are few restrictions on its use. Zinc oxide has similar properties. Ammonium sulphate solution (Stingose). This has been claimed to have a de-naturing effect on the proteins introduced by bites and stings, but the claim dates back to one academic paper in 1980 and should be treated with considerable skepticism. There is little or no objective evidence of its effectiveness (except, perhaps, for stings in the marine environment from jelly fish nematoblasts) nor is there a credible explanation of how it would work in the case of subcutaneous terrestrial stings. Systemic, toxic and anaphylactic responses A systemic reaction can be mild and manifest as purely cutaneous (skin) responses like hives (but distant from the sting site) and typically involves the trunk or scalp, and/or a rapidly-developing swelling of the face. Gastrointestinal symptoms may also occur, and include a metallic taste, nausea, vomiting, diarrhea, and abdominal cramps. Attendant neurologic symptoms include light-headedness, dizziness, (which can also have a cardiovascular cause) and tremor. “Systemic and toxic reactions to stings should be managed with supportive care, including oxygen and intravenous fluid therapy, and pharmacotherapy with intravenous analgesics, H1- and H2-receptor blocking antihistamines, and corticosteroids. Anaphylactic reactions must be managed promptly with immediate airway and circulatory support, including subcutaneous and intravenous vasopressors, specifically adrenalin, and intravenous fluid resuscitation.” That’s another way of saying “You need to be in hospital.” All patients at high risk of any systemic allergic reaction to hymenopteran stings, even those who have undergone successful venom immunotherapy, should carry an emergency kit containing pre-filled adrenalin syringes while outdoors and wear a medical alert identification bracelet or tag. Adrenalin must never be injected intravenously, and preferably, not subcutaneously, only intramuscularly. Patients must be cautioned against injecting adrenalin solutions into their fingers, which could result in ischemic distal digital necrosis, over superficial veins, which could result in rapid vascular up-take, or near the sciatic nerve in the upper, lateral quadrant of the buttocks. A study done in Canada showed that adrenalin for first-aid treatment of anaphylaxis in infants using the ampoules/syringe/needle method is not practical. Most parents were unable to draw up an infant adrenalin dose rapidly or accurately. Someone operating under stress is also unlikely to be able to give the correct dose, but an adult body mass will be more tolerant of small mistakes. Fortunately anaphylaxis is a rare event. In the US about 80-90 people a year are killed by lightening (in NZ it’s less than one), and around 40 people die from insect stings (less than half are honeybee stings). In the general population somewhat less than one per cent are likely to be hypersensitive. The prevalence of hypersensitivity reported is not adjusted for climatic differences between regions or countries, and doesn’t account for the temporal or geographical distribution of Hymenoptera. Ocular stings Sting injuries have long been recognized as a significant source of eye trauma. Sting injuries can affect a variety of ocular structures, and patients typically present with an acutely painful red, watery, swollen eye. The area may be indurated (firm and nodular) around the site of sting, and the retained stinger may be visible. In addition to the immunological and toxic effects the eye can suffer significant mechanical harm. The stinger is composed of hard chitin. As noted, the honeybee’s sting is barbed and cannot be withdrawn, and while wasps and bumblebees do not possess a barbed stinger, portions of this structure may occasionally break off and remain in the tissue. Direct injuries to the lid may involve penetration of the tarsus, in which case not only will there bee a reaction to the venom, but also the disembodied stinger may damage the corneal surface. Sting injuries to the ocular structures therefore often result in a puncture wound and infection from a foreign body. Ocular complications include a retained foreign body, conjunctivitis, corneal swelling or perforation, bleeding, uveitis, blistering of the conjunctiva (chemosis), painful corneal inflammation, pupil dilation, optic nerve swelling and damage, including acute and irreversible demyelination of the optic nerve, cataract formation (notable with wasp stings), and deformation of the lens iris and cornea. Retained stingers should be removed carefully and the area should be cleaned. Removal of the stinger with a jeweler’s forceps under biomicroscopy is the only sure way. Cold compresses may be helpful in limiting the secondary inflammatory response. Ice (wrapped in cloth to avoid freezing the skin) should be applied for no more than 20 minutes every hour. Oral antihistamines and anti-inflammatory agents help control associated itching and pain. In addition, more frequent administration of potent steroids for treating uveitis aggressively and proactively has been recommended to help prevent long-term effects, like cataracts, iris atrophy and glaucoma. In particular, for victims with toxic optic neuritis, early intervention with a three-day course of intravenous methyl-prednisone followed by a tapered dose of oral prednisone over seven additional days has been shown to help patients recover their sight following this type of trauma. Beekeepers Beekeepers have a significantly higher probability of being stung, and a far greater exposure to bee-related antigens than the general population. They have a greater risk of allergy and anaphylaxis; various studies have suggested rates of allergy between 17-43%. In a study of German beekeepers 4.4 % reported systemic reactions to bee stings (allergic reactions), 75.6 % reported mild local reactions, and 18.6 % had no reactions to bee stings. Curiously, 25.3 % of the beekeepers reported more severe reactions to bee stings in spring than in later months. There are few studies, but this one also tried to determine what factors might explain the range of values and the risk factors that appear to predict allergy. This analysis revealed that the most significant factors, in descending order of importance, were symptoms of upper respiratory allergy while working with beehives, susceptibility to allergies in general, time spent as a beekeeper, fewer than ten stings per year, and more severe non-allergic reactions to bee stings in spring. In addition, age, and body mass (but not sex), were inversely correlated with the probability of a systemic reaction, but could not be used as a predictive factor. Using the main factors identified by the study the researchers could correctly classify the allergic reactions in 85.2% of the cases. When comparing studies, much of the variance in the incidence of allergy reported could be successfully explained by the age of the beekeepers used by the different studies. To put all this another way, if you are a new beekeeper, young and skinny with a history of other allergies, and develop respiratory or skin problems when handling bee equipment and haven’t been stung much, then your risk of having a systemic reaction one day is much greater compared to the big crocodile-skinned old geezer who hasn’t worn gloves in years and drinks too much beer (but it should decline as you become a crocodile-skinned…). It might be wise to make sure someone knows when and where you are working with bees About 25 % of beekeepers have high anti-bee venom IgE levels, and all beekeepers have increased anti-bee venom IgG. Despite this, anaphylaxis to bee stings only occurs in a minority of these individuals and we don’t know why. Repeated exposure to the venom leads to a change in the way the lymphocytes in the immune system react to the particular offending antigen. The cells switch antibody production from allergic IgE to non-allergic IgG which cannot cause mast cell activation, and there is no subsequent anaphylaxis. Controlled venom immunotherapy is very successful at ‘de-sensitising’ individuals who have become hypersensitive. Even without considering immunology, being stung is, at best, irritating. In the case of stings to the face they can be debilitating, and especially around or on the eyes, permanently disabling. Mass stinging events can be life threatening. Beekeepers use several methods to mitigate the risk, avoidance (by good technique), evasion (planning an escape route), and physical protection (Personal Protective Equipment - PPE). Beekeepers are able to breed strains that show a considerable difference in their propensity to sting and generally select calm, peaceable populations to work with. The most essential of these strategies is to use a well designed veil; we have seen how dangerous a sting to the eye can be. Consider that dark glasses will make the face and eyes a target. Bees that get in under the veil, or get tangled in hair, are best dispatched between finger and thumb. If a lot of bees get in (not just one or two), walk away, if possible cover your eyes and face with your hands and remove the veil to let the bees out. Clothing fulfills various needs (not just protection), and should be practical, comfortable, washable, and light-coloured, and should not trap bees in the fabric or on the inside! Knowledge of bee behaviour allows a beekeeper to anticipate how bees react to visual cues and scents so that, for example, movements are conducted with finesse, and colours, perfumes and smells that disturb the bees are not used or masked. Gentle techniques, and the act of timing hive manipulations favourably, develop with experience. Stings and any squashed bees are best removed and the site smoked so that guarding bees are not encouraged to sting. Hive design and construction, and position, the weather, bee-forage, and the seasonal life-cycle of the colony and its neighbours all contribute to the need for a colony to heighten or lower its defensive response to a beekeeper’s attentions. It is unwise try to ‘work though’ a situation where stinging or robbing is getting out of hand. Caring for others Plan and prepare your response in advance. Communication, transport, supervision, etc. After a sting… Get you and the victim away to a safe area Remove the sting as quickly as possible Relieve the local symptoms with ice, calamine, ibuprofen and liquid/tablet antihistamine as required/available. Observe, and take action if you see · Stings to the eye, mouth or throat · Swelling of lips, neck, face, or eyes when they have not been stung · Hives or welts · Abdominal pain, vomiting ACTION · Stay with patient and call for Ambulance · Give medications if prescribed (eg. Antihistamines) · Locate EpiPen® or EpiPen® Jr if prescribed · Contact emergency contact/parent/carer WATCH FOR SIGNS OF ANAPHYLAXIS (severe allergic reaction) · Difficulty / noisy breathing · Swelling of tongue · Swelling / tightness in throat · Difficulty talking and / or hoarse voice · Wheeze or persistent cough · Loss of consciousness and / or collapse · Pale and floppy (young children) DO NOT GIVE YOUR PRESCRIPTION MEDICINES TO SOMEONE ELSE References Arcieri, Enyr Saran M.D.; França, Edimar Tiago M.D.; de Oliveria, Hailton Barreiros M.D.; De Abreu Ferreira, Lizane M.D.; Ferreira, Magno Antônio M.D.; Rocha, Flávio Jaime M.D., Ocular Lesions Arising After Stings by Hymenopteran Insects, Cornea, April 2002 - Volume 21 - Issue 3 - pp 328-330. James H. Diaz, Hymenopterid Bites, Stings, Allergic Reactions, and the Impact of Hurricanes on Hymenopterid-Inflicted Injuries, (2007), J La State Med Soc VOL 159. B.J. Donovan, Anaphylactic shock and strong cardiac stimulation caused by stings of the bumble bee Bombus terrestris (Hymenoptera: Apidae), The New Zealand Entomologist, 1978, Vol.6,No.4, pp385-389. Buddy MarterreMD., Bee stings, immunology, allergy and treatment, American Bee Journal (Aug 2006). K Münstedt, M Hellner, D Winter, R von Georgi, Allergy to Bee Venom in Beekeepers in Germany, J Investig Allergol Clin Immunol 2008; Vol. 18(2): 100-105. Hiten G Sheth, and Timothy J Sullivan, Optic neuropathy and orbital inflammatory mass after wasp stings, J R Soc Med. (2004) September; 97(9): 436–437. P Kirk Visscher, Richard S Vetter, Scott Camazine, Removing bee stings, (1996), The Lancet, Volume 348, Issue 9023, Pages 301-302. Dave Black (2013)
  19. 4 points
    Social insects like honeybee living in close proximity have a higher risk of spreading diseases and poisons among nestmates, so we would expect to find mechanisms that mitigate this. One of these systems is an innate immune system that provides an antimicrobial film on their exoskeleton, a hostile gut environment, a peritrophic membrane and gut epithelium, and effective cellular and humoral defences. These secrete antimicrobial chemicals, engulf or entomb foreign materials, and provide enzymes that degrade or destroy pesticides and pathogens. The genetic precursors for all this are ancient, common to invertebrates and invertebrates, and consequently fairly well understood. If we compare honey bees to other solitary insects we find that, relatively, honey bees have about a third as many of the genes known to be associated with disease immunity. Partly that is likely to be because they are targeted by fewer, more specialist pathogens, and live in a very stable nest environment, but it’s also because they use a highly developed strategy that combines behavioural traits that together provide a social immunity. Collectively, they construct or maintain nests using antimicrobial materials, keep their young in hygienic, homeostatic, sterile nurseries, create a ‘fever’ in response to disease, functionally exclude foraging bees from parts of the nest, groom, exhibit ‘altruistic’ suicide, and delegate risk-taking to expendable members of the group. These behavioural traits seem particularly important and yet we know very little about them, how they work, and how they are inherited, even after decades of ‘trial & error’ field research has shown that they are highly effective and highly inheritable. A group of researchers in Canada are involved in a long-running project studying the basis for inheritance of this social immunity. The scale and duration of the study differentiates it from most. Their most recent paper was just published last month. For this study they created two selected populations (of 100 colonies each) that express hygienic behaviour (using freeze-killed brood) across three generations relative to a ‘baseline’ 100 colony population (control). They used genome sequencing to identify genetic ‘loci’ that were associated with the variation in behaviour. The genome sequencing allowed them to consider 2,340,950 SNPs. (Think of SNPs as alterations in DNA sequences – a person will have four to five million SNPs in their genome). The researchers identified regions in the genome that differed between the study and control group down the generations, homing in on 10,140 SNPs, and then compared their candidates to six other, independent studies which at first zeroed in on 2,058 SNPs in 99 regions in the genome, and they then refined that to 73 protein-coding genes that looked to be the most significant in terms of hygienic behaviour. Usefully, perhaps surprisingly, 85-90% of these genes were not unique to honey bees but are shared with other hymenoptera and insects in general. These genes are already all known to be associated with the functioning of features of the neurological system, for example in nerve growth and signal transmission, and olfaction. Rather than novel genes being responsible for hygienic behaviour, it seems that existing genes and gene networks are conserved and ‘repurposed’ during adult development or maturation, perhaps by a difference in the regulation of a pre-existing ‘tool-kit’. But keep that 73 genes in mind. The authors also claim that the ancient genetic ancestry of their selected, hygienic genes had much more in common with C-lineage (Central European) Apis bees (ligustica; carnica) than M-lineages (mellifera) or O, A, Y (Mid-East, Africa, or Yemen, Saudi). This is interesting because many other studies (six are mentioned) have independently come to the same conclusion, that C-lineage bees (carrying C-lineage genes) have superior hygienic abilities. This is the fourth paper in this vein from this group so far. They began (2010) by looking for signs of local adaption in honey bees, establishing and comparing populations from within Canada, but also including some from Chile, California, Hawaii, and Hawkes Bay, because that was where they were buying queens and packages from. They were interested in seeing what trade-offs were being made, if any, by the necessary import of, possibly, mal-adapted stocks. They were able to show distinct metabolic adaptions that related to the geographical source; in some respects, metabolically, NZ bees had more in common with Chilean bees that with Canadian bees. In their words, “The populations studied… may represent separate geographical ecotypes, where metabolic control and protein synthesis/folding mechanisms has been finely tuned to confer fitness to local environmental pressures such as climate, food resources, predation and diseases.” The second paper released (2015) used a subset of the same bee population (without the NZ bees as far as I can tell) to see if it would be possible to use molecular markers rather than behavioural tests to select more disease resistant stock, since that would be faster. They suggest biomarkers in the form of the expression of a particular set of proteins would be a better tool than conventional Marker-Assisted-Selection (They looked specifically at odorant-binding proteins in antennae that correlated with hygienic behaviour). The third paper (2017) has a more detailed demonstration of an ‘expression marker’ as they call it, successfully testing the idea against AFB and varroa in a selection and breeding programme lasting three years. This is how they sum up that paper; “[Marker Assisted Selection - MAS] has the potential to be more precise and more robust to external influences; it has been widely used in certain plants and animals. To date, however, the markers used have been genomic loci exclusively...undoubtedly due, in part, to the availability of efficient genetic approaches for finding such markers. It is also a matter of focus: researchers have spent more time looking for genetic loci than for expression markers... Here we have shown that expression markers can be used to select for a very complex, polygenic trait. (Remember the 73 genes?) Even in this proof-of-principle with a first-generation panel of markers, MAS was as efficient at enriching disease-resistance as Field Assisted Selection [FAS] methods: bees bred using marker-assisted selection could resist levels of disease that would typically kill 70% or more of unselected colonies. The data presented here have implications beyond bees: this is the first demonstration of marker-assisted selection in livestock using expression markers and it enables molecular diagnostic approaches for selecting complex polygenic traits that are recalcitrant to genetic mapping methods. After three generations of selection, the resulting marker-selected stock outperformed an unselected benchmark stock in terms of hygienic behaviour (sic), and had improved survival when challenged with a bacterial disease or a parasitic mite, similar to bees selected using a phenotype–based assessment for this trait. This is the first demonstration of the efficacy of protein markers for industrial selective breeding in any agricultural species, plant or animal.” Just because I can - it seems to be a major topic of discussion at the moment, I’m going to note how all this was funded; a muti-site, international, nine year project using several hundred colonies and some expensive, novel, lab work. Here is a list of the bill-payers; Genome British Columbia, the British Columbia Honey Producers Association, the Canadian Honey Council and Canadian Association of Professional Apiculturists through the Canadian Bee Research Fund, the British Columbia Blueberry Council, the British Columbia Cranberry Marketing Association, Agri-Food Canada’s Advancing Canadian Agriculture and Agri-Food (ACAAF) program, Ontario Genomics, a Discovery Grant from the Natural Sciences and Engineering Council (NSERC) of Canada, Genome British Columbia, Genome Alberta, the University of British Columbia, the University of Manitoba, and the US Department of Agriculture. I haven’t included odd scholarships or research grants supporting the tenure of individuals. Food for thought. Brock A. Harpur, M. Marta Guarna, Elizabeth Huxter, Heather Higo, Kyung-Mee Moon, Shelley E. Hoover, Abdullah Ibrahim Andony P. Melathopoulos, Suresh Desai, Robert W. Currie, Stephen F. Pernal, Leonard J. Foster, and Amro Zayed. (2019) Integrative genomics reveals the genetics and evolution of the honey bee’s social immune system. Genome Biol Evol. 2019 Feb 15. doi: 10.1093/gbe/evz018 Guarna MM, et al. 2017. Peptide biomarkers used for the selective breeding of a complex polygenic trait in honey bees. Scientific Reports 7: 8381. Guarna MM, et al. 2015. A search for protein biomarkers links olfactory signal transduction to social immunity. Bmc Genomics 16: 63. doi: 10.1186/s12864-014-1193-6 Parker R, Melathopoulos AP, White R, Pernal SF, Guarna MM, Foster LJ. (2010) Ecological adaptation of diverse honey bee (Apis mellifera) populations. PLoS One. 2010;5(6):e11096.
  20. 4 points
    The promiscuity of honey bee queens generates lots of interesting questions about social insect society, many of which relate to the many different ‘sub-families’ that co-exist within a colony. For example, do individuals within a colony overcome their self-interest to rear the ‘best’ replacement queen in an emergency or do they try to pick their closest relative? Just how far does social co-operation extend? Emerging recent research is starting to suggest that, apart from picking well-fed larvae of the optimum age, workers tend to select larvae from particular ‘royal’ sub-families. If that turns out to be true, we may well have some of our ideas about honey bee queens wrong. Most of our contemporary ideas about the ‘families’ in a honey bee colony stem from studying the genetics of individuals in the colony. The workers in the hive are all sisters, daughters of one queen ‘mother’, but they have many fathers, depending on which particular sperm fertilised the egg they hatched from. Usefully, the lengths of inherited genetic material we call genes contain non-functioning stretches of repetitive elements that we can look at easily. These are known as ‘microsatellite’ markers, and because they don’t code (for proteins) chance changes in these areas don’t affect protein coding and can accumulate, providing a record of change and relationship we can read. Typically researchers amplify the sections of DNA they are interested in using PCR, at the same time tagging the microsatellites with fluorescent markers. As the repeated sequences have different lengths and masses these can then be seen using (for example) chromatography. Researchers will choose a number of microsatellite markers that are relevant to whatever they are studying, say 3 – 8 different ones, and then group individuals that share common sets of markers. People looking at this sort of thing will collect lots of workers, analyse the microsatellite markers, and work out the number of different drones there must have been in order to produce the number of different families of worker they have. They have shown that, for a considerable period (many months), the composition of the families remains much the same, suggesting that drone semen is pretty well mixed after mating and used randomly. Over the long term however (up to 4 years) the make-up of the sub-families do change, possibly a consequence of the filling sequence and changing sperm density in the spermatheca, and maybe evidence of ‘cryptic female choice’ or sperm competition in honey bee queens. Lately, some studies have begun to include queens in the microsatellite analysis, and discovered sets of families that are unique to queens and do not appear if you just examine worker offspring. These ‘extra’ families suggest that queens actually mate with more drones that we thought, rather than 10 – 20 being a ‘normal’ number, 20 – 40 might be more accurate, and actually more in line with that reported for other honey bee species. These ‘royal’ sub-families appear to be quite rare, and stay that way, despite the apparent advantage natural selection would give them if they are more attractive to queen-rearing nurses. That’s likely to be because emergency queen rearing is a relatively rare event so workers seldom get a chance to exercise any preference, and because there are other factors that determine the result in any case. Nevertheless several studies suggest that, in the case of queens raised in an emergency, the choice of which larvae to pick is biased towards particular ‘royal’ subfamilies rather than towards the workers’ own subfamilies. Withrow JM, Tarpy DR (2018) Cryptic "royal" subfamilies in honey bee (Apis mellifera) colonies. PLoS ONE 13(7): e0199124. https://doi.org/10.1371/journal.pone.0199124 Moritz RFA, Lattorff HMG, Neumann P, Kraus FB, Radloff SE, Hepburn HR. (2005) Rare royal families in honeybees, Apis mellifera. Naturwissenschaften. 2005; 92:488±91. https://doi.org/10.1007/s00114-005-0025-6 PMID: 16151795 Brodschneider, R., Arnold, G., Hrassnigg, N., and Crailsheim, K. (2012) Does Patriline Composition Change over a Honey Bee Queen's Lifetime? Insects 2012, 3, 857-869; doi:10.3390/insects3030857 ISSN 2075-4450
  21. 3 points
    The drawn empty frame I checkerboarded a week or so back has now been populated with eggs and newly hatched larvae, honey and pollen stored as well. There is lots of natural pollen coming in now and the bees have mostly left the pollen patties alone. As the colony grows there are a couple of older brood frames that will be cycled out to make way for new frames.
  22. 3 points
    For most of us viruses are confusing. Many people are unable to distinguish between viruses and bacteria and expect them to be much the same kind of thing, which they are not. Viruses don’t fit easily in to the various categories of living things we are used to dealing with, and actually whether they even are living organisms is arguable, and how they came to be still more controversial. Which is why there is never a clear answer about how we might kill a harmful virus. Viruses are not cells and can’t reproduce on their own, and some see them merely as parcels of genetic material (most often RNA) that have just gone rogue, a molecular accident. To coin a phrase ‘bad news in a protein coat’, although, not all viruses are harmful. For others they are an extreme simplification evolved from ancient living cells. At the moment, the former guess seems the more likely. Part of the reason for that is a growing understanding about how cells communicate. While we have known for a long time the cells can secrete chemicals, it’s only in the last ten years or so that scientists have realised that they do much more. Cells produce small ‘packages’ of molecules, including the RNA that can be translated into proteins or which affect gene expression, in great quantities all the time, and in every body fluid they have tested. These packages are produced as ‘bud’s from the cell wall, or from within the cell contents and released through the cell wall, and many of them are uncannily like viruses in size and structure. Not un-naturally this has led to speculation that maybe extra-cellular vesicles and viruses were two extremes on the same continuum. The evidence that ‘messenger’ fragments of RNA in extra-cellular vesicles are a form of communication is substantial, and we are beginning to realise how widespread this is, finding it throughout animal and plant kingdoms. What is also becoming clear that part of this communication is involved in the on-going ‘war’ between infectious viral agents and their hosts, facilitating or defending against invasion. Viral RNA communicated to another organism in an extra-cellular vesicle can pre-emptively prepare a response, a non-infectious vesicle-virus ‘inoculating’ a host against the infectious ‘real thing’. Scientists have also found instances where host genetic material and viral genetic material have become intertwined over millennia, not just as junk or contamination, but conferring new functions on the host. Viruses seem to provide a ‘library’ of genetic material, freely used by all other organisms. Instances of RNA ‘interference’ (iRNA) in honey bee biology have popped up in recent years. It has been suggested that iRNA (or gene ‘silencing’) has a role in determining honey bee castes (worker vs queen) and other epigenetic effects, and that a honey bee virus (IAPV, once talked about as a candidate for causing CCD) can be treated with iRNA from the right dsRNA fed in syrup. An iRNA treatment for varroa mites is the subject of a US patent*. iRNA is now known to be an important response to control viral infections in many insects, not just bees. What the latest paper from Maori et al (who hold the RNA/varroa patent) suggests is that social honey bees have the ability to pass an acquired immune response to each other and to larvae while food sharing, providing long-term, intergenerational, colony level protection circumventing a non-existent hereditary mechanism and boosting a naturally depauperate immune response. “It is generally agreed that RNAi evolved as a defense mechanism against selfish nucleic acids and further diversified to regulate endogenous gene expression. The presence of differential naturally occurring RNA among worker and royal jellies points towards a potential effect of transmissible RNA on genome function in recipient bees. Indeed, supplementing jelly with endogenous or exogenous miRNAs that are naturally enriched in worker jelly affected gene expression as well as developmental and morphological characters of newly emerged workers and queens. We speculate that bee to-larva RNA transfer could also play a role in epigenetic dynamics among honey bees…” Esther Nolte-‘t Hoen, Tom Cremer, Robert C. Gallo, and Leonid B. Margolis (2016). Extracellular vesicles and viruses: Are they close relatives? PNAS August 16, 2016 vol. 113 no. 33 9155–9161. www.pnas.org/cgi/doi/10.1073/pnas.1605146113 Knip M, Constantin ME, Thordal-Christensen H (2014). Trans-kingdom Cross-Talk: Small RNAs on the Move. PLoS Genet 10(9): e1004602. doi:10.1371/journal.pgen.1004602 Zhu, K., Liu, M., Fu, Z., Zhou, Z., Kong, Y., Liang, H., Lin, Z., Luo, J., Zheng, H., Wan, P., et al. (2017). Plant microRNAs in larval food regulate honeybee caste development. PLoS Genet. 13, e1006946. Garbian, Y., Maori, E., Kalev, H., Shafir, S., and Sela, I. (2012). Bidirectional transfer of RNAi between honey bee and Varroa destructor: Varroa gene silencing reduces Varroa population. PLoS Pathog. 8, e1003035. Eyal Maori, Yael Garbian, Vered Kunik, Rita Mozes-Koch, Osnat Malka, Haim Kalev, Niv Sabath, Ilan Sela and Sharoni Shafir, A transmissible RNA pathway in honey bees (2018). bioRxiv preprint, doi:http://dx.doi.org/10.1101/299800. * https://patentimages.storage.googleapis.com/e5/73/68/9da2474916fe03/US8962584.pdf
  23. 3 points
    Getting colonies sorted today for a sale I made, so while in the back yard I checked on the nucleus colonies I have been building up over the past few months. Nucleus 1 is now covering 4 frames and has 2 frames with brood on both sides, a total coverage of about 1.5 FD frames. This is excellent and the colony is heading in the right direction. By the end of August I reckon I will be moving them over to a 10 frame box. Nucleus 2 has done extremely well and today was used to make up a larger colony with the addition of Bees and brood frames from a very strong 2 box colony ( it had Drones in Drone cells and 6 frames of capped worker brood). Another Nucleus colony that has been part of the experiment was used to requeen a queenless colony. This was done with newspaper over the bottom queenless colony then a queen excluder. The plan is to have the two colonies combine but give the queen a bit of protection until they become a happy family.
  24. 2 points
    Checked both hives. The split hive was fed syrup for the past week to encourage comb-drawing, which has worked very well - the checkerboarded top box has a good amount of uncapped syrup on freshly drawn comb and the queen is busily laying in the middle - no queen cups / cells. Sugar shake tested for varroa from brood frames, no mites fell on the plate. Removed varroa strips and the top feeder, added a honey super above QE. Happier about the stores situation now than I was last week - the bees have put a good amount of syrup / nectar away and there's plenty of pollen around the brood nest, both coming in and stored away. The other hive was doing well, however saw 2 queen cups with eggs. Not properly drawn, just a play cup shapes...but with an egg in each. Moved emptier frames from the bottom box to the top FD in the middle where the queen is laying to give her space, removed one old frame with mostly drone brood and replaced with an empty frame. Removed varroa strips and added a honey super above QE. I need to keep an eye on this one in the next week to see if I need to take further measures to prevent swarming. Didn't do sugar shake but tore open and inspected a bunch of capped brood from the frame I removed. No varroa seen - either it's a good result and the strips have knocked them back or I'm not very good at spotting the mites...but I've seen them before easily enough so I'm reasonably confident that the treatment was effective. A pretty disruptive day at the hives - tried to be careful but wasn't 100% sure of where the queens were for some of the time. I hope I didn't roll one by accident.
  25. 1 point
    Both hives checked. The 2-queened hive is really pumping - having one queen in each FD and placing a QE in between was a great tip, as now I can better see what's going on. The new queen is laying up a storm - the old one is still laying but not as well. The hive is full of bees and the bees are 'holding hands' big time - they are even hanging below the hivedoctor base. Despite this, there is still space to lay and to store honey. Hopefully checkerboarding emptier frames to the middle will help so that the bees don't do anything silly before the varroa strips are coming out in 2 weeks' time. There isn't a lot of stores in this hive but there's still pollen, capped and uncapped honey in there and the new grubs look nice and wet so it looks like the build up is being fed from the incoming nectar/pollen. I still have the granulated sugar at the top, which has been taken in but not very fast. If I don't have to feed syrup I'd rather not, as there isn't a lot of room for more build up really - just need to make sure the bees don't starve if we get poor weather. Ideally this hive would just stay this strong but not run out of control for another 2 weeks, at which point a super is going on the top. Also forked out a few drone pupae to check for varroa & matchstick-poked a few capped brood cells. No varroa found and no ropey goo, so that's good. I saw a few bees with a relatively black-looking (hairless) thorax - they seemed to be acting normally so maybe they are just old and worn out rather having chronic bee paralysis virus...but who knows. The other hive is doing well at a more measured pace - I guess they only have one queen so it only makes sense. I'm happy with their progress also, though - a good amount of stores, uncapped & capped honey and brood. The top box was getting really full so moved some empties from the bottom FD up to give a bit more space. Again, I mainly want to keep things under control until super time, at which point frame-drawing should keep the girls too busy to even consider swarming (I hope). Carefully hopeful about how things are going - I certainly have a lot more bees than I did this time last year.
  26. 1 point
    A quick AFB matchstick test for one of the hives - no symptoms but wanting to be sure. Further inspections stopped by rain...followed by hail. Thanks Auckland.
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