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Dave Black

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Dave Black last won the day on July 16 2018

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About Dave Black

  • Other groups BOP Beekeepers,
    Club Leaders
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  1. It’s a complicated thing. There are plants that do not require pollination of any kind to produce fruit and seeds. There are some that require the stimulus of pollination, but not actual fertilisation, to fruit. Where pollination is required a plant may use pollen that it has produced (in the same or a different flower), or may have to use pollen from another, distant, plant of the same species. Unfortunately too, there are plants that have a bet each way, both ‘cross-pollinating’ and ‘self-pollinating’. Pollen is passively dispersed by currents of air and water but animals can be induced to visit flowers for rewards like pollen itself, nectar, resins, and oils, or even by deception, in order to carry pollen to another plant. A pollen vector has to transport a quantity of viable pollen to a receptive part of the plant (the flower stigma), and we look for direct (pollen grains) and indirect (fruit or seed set) evidence that this has happened. That’s pollination. We have to understand the possible plant reproductive arrangements to work out what contribution any given pollinator might be making, and we have to understand a lot about possible pollinators, their morphology, seasonality, nutrition, and behaviour, for example. Many of our fruit and seed crops benefit from being assisted in this way, and for some it is essential. In these cases the important visitors are almost always insects. We call this ‘entomophilus’ pollination, and improving the circumstances in which insects (and a few other small ‘bugs!) operate can result in quantitative and qualitative improvements in yield, and better financial and nutritive outcomes. Observing pollination in order to make such improvements is not however straightforward. We have to be able to look at the biology of both the plant and the animal in unaccustomed detail and understand how each has to respond to fluctuating environmental conditions. Not only that, but consider that ‘crops’ are a social construction and a part of a market economy. ‘Crops’ are much more than their biology. Studying pollination Agents capable of pollinating flowers can be abiotic (wind, water, gravity, electrostatic forces, rain) or biotic (such as birds, bats, insects, mammals). Any one of these may be capable of meeting all or part of a plant’s requirement. Biotic pollinators are different in that the relationship is built on some form of exchange (even if a fraudulent one) that is advertised, desirable, rewarding, social, and constrained. There are then questions to be asked about how the potential exchange is communicated and to who, the costs and benefits of the ‘reward’ to each party, choice and competition between the interests of the individuals and the populations they are part of, and the ‘rules’ that affect the trade (physical, chemical, and biological), things like pollen presentation, anther dehiscence, flower duration, stigma receptivity, and the physical ability of particular pollinators. Much of the 'mechanics' of observing pollen transfer is tried and tested and standard methods have been worked out. Often, pollination studies tend to stop short of including fertilisation; the conditions for good pollen viability, germination, pollen tube growth, and pollen (in)compatibility have to be found elsewhere but actually form part of the ‘whole picture’. Rarely do studies give much thought to the actual transportation; how does the pollinator find, collect, and carry pollen? In the case of honeybees the COLOSS Beebook describes protocols for identifying and evaluating pollen quantity and quality transported by bees, evaluating the same deposited on stigmas, estimating the proportion of foragers from a colony visiting a crop, observing bee densities in field plots, appraising the effect of competition between plants for pollination, and conducting pollination research in unusual environments like greenhouses. DNA meta-barcoding is beginning to be used to identify pollen loads, sigma deposits, and track pollen flow. These kinds of protocols are generally equally applicable to most pollinators and are intended to ensure studies are robust, comparable, and repeatable, but beyond collecting observations about the process of transportation, pollination studies have a long row to hoe. The ‘Nature’ of advertising Plants, and pollinators, have options, some more than others. Before any kind of exchange can take place plants have to prompt pollinators to come visiting (plants are, literally, rooted in place), but leaving food rewards out for all and sundry will hardly achieve the required outcome. Successful pollination has come to rely on signals, simple, elaborate, and occasionally dishonest, for communicating necessary information. From one perspective, plants 'advertise' in a marketplace for service, and the most obvious representation of that advertising are flowers. In markets, supply and demand fluctuate. At any point in time there may be a surplus or deficit of flowers relative to the number of pollinators. Increasing competition between flowers might result in an increased investment in rewards and display; reduced competition might have the opposite effect. Advertising comes at a cost and in the end a plant’s pollination and reproduction will depend not only on the efficacy and ‘value for money’ of its own signals but also on the signals of co-flowering species, their distribution, and relative abundance. We do not see the world as others see it. Signals that plants can produce that can be perceived from a distance fall into two types. There are those that make use of the electromagnetic spectrum, (that we refer to as colour – a limited part of the spectrum), and the emission of volatile chemicals (some of which we smell). Such signals can be tailored so that they are detected by a broad range of pollinators, or only by a few specific pollinators, perhaps one, and not necessarily by us. They may indicate the reward is available, exhausted, or located in a specific place. Comparatively well known, colour and ultra-violet ‘nectar-guide’ patterns can be accompanied or supplanted by far more important but cryptic ‘odour-guide’ patterns. Olfactory signals appear to be especially easy to learn and remember, at least for bees. Some recent studies suggest ‘odour plumes’ sometimes used by pollinators can be disrupted by anthropogenic pollution, such as ozone and diesel. Signals are easily overlooked or misunderstood in pollination studies because it’s necessary to recognise if and when a specific animal will sense a particular signal, and how that will be understood, prioritised, and remembered. Temporal change in food networks Nectar is essentially a modified phloem exudate available as a carbohydrate food reward for pollinators, mostly a source of energy. Plants can control nectar secretion and can adjust it according to rate of consumption, temperature, or humidity. In some plants there is a daily rhythm to production, in others it is clearly under the control of a hormone. The ‘transience' of the secretion serves to conserve an expensive product; in some examples nectar secretion was estimated to account for nearly 40% of the total carbon absorbed by the plant. The main carbohydrate is sucrose which is metabolised in a time/temperature-dependant way, by enzymes (‘invertase’) on the cell walls of the nectary tissue, to hexose sugars. Some invertase remains in the nectar, so the nectar sugars continue to change composition with time. Sugar solutions are also hygroscopic to varying degrees, so their concentration is not fixed, nor is the viscosity. The environment has an effect on the nectar itself, humidity and heat changing the physical properties of the solution. Besides sugars, there are other constituents that matter. Minerals, amino acids, enzymes, alkaloids, volatiles, and antimicrobials are selectively attractive and unattractive to various flower visitors, by design. Microbes (like yeasts) come to inhabit the nectar and are also responsible for significant changes to its composition, and its allure. Pollen is foremost in the mind looking at pollination of course, but besides the obvious function for the plant it is also a food reward for the pollinator, but, unlike nectar, directly linked to a plant’s reproductive success. It, and its compliment of microbes, is the major (perhaps the only) source of food required for pollinator activity, growth and repair, comprising amino acids, fats, oils, and minerals. It comes ‘packaged’ in a huge variety of perishable forms, sometimes ‘labelled’ with aromatic or gustatory compounds that try to protect it from or limit herbivory (for example, alcohols and phenols like linalool or perseitol). Bees’ aversion to chemically defended pollen depends on what else is available, and they can be put off the whole patch by a few unpleasant flowers. As a valuable product pollen supply can be constrained by things like morphology, by environmental factors (for example, temperature and humidity restraining antithesis), by its longevity, and by competition or theft. There is an obvious tension between pollen being both food and the object to be transported. Some pollinators specialise in one, or one or two, types of pollen, while others require a great variety. Lately there is a suggestion that stoichiometry may be a guiding principle when it comes to what pollen suits a particular pollinator. While there is scant evidence that pollinators are able to assess its food value, there is plenty of evidence that they select on the basis of its physical form, its presentation or accessibility, odour, or taste, and that their appetite or tolerance for different pollens changes depending on, for example, scarcity or abundance. In practice then, nectar or pollen can be harvested by a parade of visitors as time and circumstance change; visitors with different mouthparts, different appetites, and different priorities. Pollination studies consequently have several questions to think about. How, and when, is the supply of nectar and pollen regulated? How do we account for depletion by visitors, by wind, rain, heat, and humidity, or by the plant conserving it? How can we determine if and when the temporal changes in its chemical and physical properties affect its attraction and utility for different visitors? Last, how well does a given pollinator compete with the other flower visitors, and do they need to? The importance of memory In recent times navigation and memory have become topical and the subject of some studies that suggest impairment of these functions can occur following exposure to agricultural chemicals, although so far it is hard to see how the comparison is being made with only a rudimentary understanding of what the ‘baseline’ is. Pollinators are thought to acquire information about the location of their nest-site and food sources in ways that are common to most if not all insect orders, the hymenoptera being the most closely studied. An insect monitors and stores distance and compass metrics derived from its own movement and is able to compare its current sensory experience with a memory of the desired sensory experience (in one expression, by matching ‘images’). Various guidance strategies allow pollinators to travel at a distance from their nest site, and with experience, to embark on, and return from, complicated journeys. With increasing experience accuracy emerges automatically as more precise or reliable cues have more successful outcomes and information from the various strategies is evaluated and refined. 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. It's clear that memory is a crucial part of the system, and that different memories are recalled ‘on-cue’ and depending for example on whether an animal is seeking food, or has gathered food; what has been referred to as 'motivational state'. We also know that memories are ‘layered’, and time dependent – they are acquired, reinforced, and extinguished in ways yet to be understood. There is a complex relationship between memory acquisition and extinction, with physiological age being a factor. 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 are thought to have a shorter memory. Forgetting what they knew yesterday encourages them to try new locations and food sources and so builds experience. This might be particularly useful for pollinators that forage on much more transient and distributed flora. We should not expect all pollinators to be the same. Bumble bees and solitary bees are masters of the local search and have progressed from simple Levy search patterns to develop very effective routes (like 'trap-lining'). Honey bees are not as efficient in the same way, however, their ability to recruit nest-mates to exploit the same resource, and their ability to navigate more effectively over large distances, ensures efficiency at the colony level. Many pollinators, and particularly honeybees, also display a learned preference for particular flowers based on memory of a previous experience. They become especially adept at recognising and manipulating a type of flower and remain loyal to it for a significant period of time, a phenomenon now known as ‘floral constancy’. It’s possible this is more important for foragers that use image matching navigational strategies. In observing pollination, a forager's motivational state, its sensory and locomotive abilities, and how and when it stores, manages, and retrieves memories is of fundamental importance if we are to understand how pollinators make decisions. Just as much as varying nutritional demands or sensitivity to signals, varying aptitude for using the same basic neurological tool-set is responsible for stratifying pollinators within a landscape and across time. Business practices and Commerce Flowering crops are unlike plants that exist in a natural ecosystem in that they are significant aggregations of selected plants purposely planted and cultivated for food or commerce. These plantings can take many forms such as pasture, field crops, agroforestry, and greenhouses, and are generally monocultures with different degrees of human intervention. The planted area can be sufficiently large that it can test the foraging range of some pollinators, modify their diet, and reduce their density to a point that limits full pollination. This can be aggravated by the displacement of local nesting sites through shading, soil tillage, and overzealous ‘horticultural hygiene’. The cyclic overabundance and famine that characterises a flowering crop is not necessarily an advantage over the lifetime of an embedded pollinator. These simplified environments are less resilient to changes in weather, season, and climate, when a single adverse event can produce unsuitable conditions that curtail the activity of insects and disturb the pollination of the entire crop. Pollinators will respond to all manner of changes, like flower abundance and diversity, climate change, land use change and intensification, and introduced species and pathogens. These responses change their distribution, physiology or seasonal phenology and so synchrony between visiting behaviour and the timing and duration of flowering. The consequences of fluctuation and change in the environment can be buffered or offset by the presence of a variety of flower visitors that can assume complimentary roles under changing circumstances. Besides one of scale, the pollination of these plants has extra dependencies that stem from sociocultural or horticultural practice and pollinator management. In horticulture the organisation of things superficially quite peripheral to pollination, for example, crop-load, rootstocks, pruning, irrigation, windbreaks, pest management, and the use of dormancy breakers or growth regulators, can have a significant impact on pollination success. Likewise, pollinators can be ‘managed’ but this only applies to a quite limited subset of possible pollinators, nearly all of them bees. Honeybees have become the most popular managed crop pollinator largely because of their persistent, perennial life-cycle, and portability. A few species of bumblebees can be managed, but like the few solitary bees that are used their colonies are fundamentally seasonal and year-round availability requires specialized controlled environments. The supply, placement, and timing of introduced pollination units, or the maintenance of pasture grazing, ‘set-aside’, headland, and field margins, are activities with their own financial costs, benefits, and risks that relate to the economy they are part of. A social enterprise The ‘outcome’ required from a flowering crop is may not be full pollination nor, necessarily, is there a long-term plan. The prominence of financial drivers and assumptions about ‘value’ quite possibly mean that what biology might see as sub-optimal may remain a preferred state when the costs of labour and horticultural management are considered. Value is at the core of many pollination studies and, as such, they need to be quite explicit about the time and spatial scales the data relate to for it to support future planning. There are useful examples that provide a social context for the relative importance of pollination compared to other interventions, and that illustrate the interplay between ‘social’ issues and crop pollination. Here are three. In New Zealand a significant number of kiwifruit blocks are now covered by a canopy. These canopies consist of a hail resistant netting supported by cables attached to 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, one is protection from the elements. Even unnoticed hail or wind damage can cause a significant fall in the return a grower gets for their fruit. Another benefit is a significant reduction in bird damage to buds and fruit, and any waste due to bird lime. The factor that may have pushed these expensive constructions 'over the line' was an introduced bacterial disease that can rapidly destroy an orchard. The canopy provides an element of phytosanitary security and protects the plants from wind damage, reducing broken shoots in the spring that are an important point of entry for the bacteria. Considering the effect these covers would have on the honeybees that are universally used to pollinate the flowers had not been a priority; unless the disease could be managed there would be no flowers. Under the covers large numbers of foraging bees failed to return to their colony and died. Those that did return delivered pollen that is mono-floral and without the proper balance of amino acids the bees require for adequate protein nutrition. A hive starved by both quantity and quality of pollen deteriorates very quickly. The loss of bees also 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 but is very quickly an ineffective pollinating unit. Many beekeepers refuse to place their hives under covers, and were in a position to send them to honey crops instead. The industry is trying a range of 'work-arounds', including alternative pollinators, aids to navigation, supplementary feed, and even supplemental artificial pollination (mechanical hand pollination if you like!). The introduced native bumblebee Bombus terrestris is a possible alternative, although not without ecological risk. Commercial supply of these is available, and it is it is possible to rear colonies locally albeit on a seasonal basis. However, where local annual production has been tried it has not been able to out-compete the supply from continuous, year round, and sometimes counter-seasonal production of large multi-national suppliers, increasing the risk to local ecosystems, and local pollinators. Further afield, in Maoxian County, Sichuan, China, by the 1980s land-tenure customs had produced quite small holdings from which farmers were being incentivised to maximise a cash return from a crop to market (rather than as food). The rules and standards in a commodity market are entirely different. The apple orchards are located in cool, mountainous regions with differences in sub-climate and elevation altering the flower phase of every orchard. Pollinators struggled. To make the most of their land-use growers reduced or eliminated polliniser trees, maximised fruiting trees, and focused on high yields, confident people could pollinate the trees reliably. Pollen could be sourced from the few remaining pollinisers however distant, shared, and people could apply it in the frequent conditions that were not favourable for bees. Relatives or neighbours might get pollen free of charge. The different flowering times enabled neighbours to help each other pollinate and close community bonds kept the labour costs down. Polliniser trees were often planted in home gardens so that flowers would not be stolen and where it was convenient for flower harvesting and pollen extraction. Pesticides could be used extensively, a disincentive for beekeepers who anyway preferred to use their bees for honey crops elsewhere. Nor was it ever clear how a beekeeper would be paid for a pollination service. Faced with a multitude of 1/5th ha land-owners, whose trees was he responsible for pollinating? Whose pollen was being used? A decade later the economy had changed again. By 2011, apple growing had considerably reduced in the most marginal areas. Climate change had increased the amount of cool, rainy, cloudy weather, the farm gate price of apples had dropped substantially, and production costs had risen, exacerbated by young people drifting to work in the cities. The famers had adapted by shifting away from apples, a crop that requires cross-pollination, to fruit and vegetable crops that were not cross-pollinated, like lettuce, Chinese cabbage, tomato, celery, onion, along with other fruit trees, such as plum, loquat, and walnut. What was the value of pollinators now? An almost identical story comes from south of Chengdu where Hanyuan County is the biggest pear producer in Sichuan. As in Maoxian, since the 1980s the area has been undergoing a transition from subsistence cereal crops to cash crops, especially pears. Most pear varieties are self-incompatible and need cross pollination to set fruit and keeping one to two colonies of honeybees (Apis cerana cerana, the Chinese honeybee) was common for some households. Until about 1985 wild insect pollinators were mostly common, and erratic fruit yield and quality were not a concern. Traditional land tenure was fragmented, land owners were often absent engaged in off-farm activities, while the small plots were managed season-to-season, the insecurity stalling investment-led change. As pear trees became more abundant insect pests (mainly fruit moths and Pollination factors.pdf aphids) flourished and entrenched extensive broad-spectrum spray programmes that also killed off the potential pollinators. This established hand pollination, but also ensured that pear trees were always over-pollinated, producing unsustainable fruit-sets and heavy, labour-intensive, fruit thinning. Returning to bee pollination is not proving to be easy, even if pesticides are controlled. Native pollinators were not scalable. Pears do not provide a nectar surplus and the bees cannot produce honey, so beekeepers in pear orchards end up incurring a cost for feeding bees with sugar syrup that they argue compounds the lost income from honey. These days China’s government agricultural officers spend their time trying to unravel these archaic interdependencies, while the rest of world uses them as poster-children for ‘bee-mageddon’. In both these cases from China some commentary framed them in terms of ‘pollination failure’ and its mitigation by (low waged – exploited) human labourers. An alternative framing might see farmers managing a family business driven by financial decisions and choosing cost effective pollinators. Looking ahead Observing pollination is an absorbing, multi-disciplinary challenge at every level of study, and one with real, tangible consequences. It can only become more important as climate change rapidly introduces yet more uncertainty about the conditions pollinators will operate under in the future. The speed of change appears to be such that some pre-emptive management is preferable to a conservative or even reactionary, response; relationships formed over millennia might alter in decades. Understanding what these are and how they operate now is vital to sustain these processes, and to construct a flexible, responsive, diversity of pollinating mechanisms that will work whatever the circumstances. We will be unable to predict the specifics of our changing climate with any certainty, and continuing a dependency on any single species of pollinator seems unwise. *“Biology is the study of complicated things that have the appearance of having been designed with a purpose”. Richard Dawkins.
  2. The group's long CoVid lock-down has been punctuated with Web-hosted virtual meetings for those able to join. This month it was out of the web-world and back to the wide-world with the group's first Honey Show. The BOP group exists to facilitate shared knowledge and experience, in a social setting where potentially everyone has something to contribute, including people that have never (or never intend to), keep their own honeybees. Keeping bees, as a hobby or a business, benefits from good information about many things, for example information about biology and horticulture, carpentry, engineering, business, to legal, employment, and compliance matters. It’s valuable then, that the group appeals to a wide range of people with different life interests. With beekeeping at the core of what we do, providing opportunities to lift the skill of beekeepers beyond proficient to real expertise is an essential process. Rather than teach, our collective role is to provide opportunities to learn, and to learn by doing, by participating, communicating, and by seeing what is possible. Honey Shows are supposed to be a test of some essential beekeeping skills. They examine the ability to harvest and pack honey and other bee products while maintaining the highest standards for quality and hygiene. They should also be aspirational and provide examples of the best that can be achieved. Some of the more peripheral talents, like brewing, making polishes and cosmetics, and cooking with honey, provide an opening for more diverse interests and supply ideas for innovative revenue streams. Creative arts exhibits celebrate novel perspectives on what we do and broaden our horizon. These are all things that provide opportunities to grow, learn, and improve. We are aware that some members are not confident about being 'tested'; about the competitive nature of such 'Shows', but that needn't be so. Yes, larger Shows can seem merciless, and pedantic, to the uninitiated. In our event you are meeting the standards we explain in advance, testing only yourself. For some classes of entry there may be guidelines or no standards. If you think you have created something that merits sharing and discussion amongst our social group then display it, it need go no further. If you wish to 'practice' or test or exhibits for larger Shows you can do that too. The BOP event is intended to be a greater test of the group than of its members. This month's test produced a range of outcomes. I can confidently say that none of the many entries in the honey class could have been prize winners in any Show so you have nothing to beat! However, every one had something to teach us, (like the use of a torch!) and all of them were available for tasting, so even bystanders got tips and a taste. The wax exhibits however included one or two entries of a high standard (potential 'winners' elsewhere) as well as some 'tutorials'. The mead section too overwhelmed us with varieties. We used a lot of lolly-sticks and tasting glasses. The DIY entries were all versions of robbing guards (!), and the 'Crafty' people supplied a decorated hive, photos, a photomontage, and pieces of wool and needlework and so on. We had more than we could comment on in the two hours-odd we had available, and more than we expected given the short notice exhibitors had to prepare.
  3. Our operators had two of these; if they are not sold they will be. The logistics just don't work.
  4. It’s hard to find a paper or article these days that doesn’t begin with a reference to “Declines in the number of global pollinator insects” or some other form of the bee or insect ‘apocalypse’ sentiment and the potential economic or ecological damage to be wrought. While one reaction to this is to prevent or mitigate the circumstances that cause it, finding alternatives to natural biotic pollination is another one to consider. At times there are clear reasons why forms of ‘artificial’ pollination are valuable, but the cost of harvesting pollen to use, and the manual or mechanical means to deliver it are expensive and imperfect. Two scientists at the Advanced Science and Technology in Japan have applied some ‘blue-sky’ thinking to the problem and come up with an unusual suggestion. They observe that is pretty easy to indiscriminately spread pollen around in an orchard, in fact the waste involved is a large part of the cost. Rather, a system must be gentle, precise, thrifty, and aerial, so what better to choose to deliver the pollen than bubbles! They see bubbles with different eyes. Bubbles can be chemically functional, light-weight, steady-liquid, bilayer molecular membranes, low cost, and bio-degradable. The pollen grains can’t scatter as they are bound by the thin film, and the bubbles are easy to create and control in flight. They can’t damage the delicate parts of the flowers, but (it’s a good thing) they are somewhat sticky. It’s obvious really. So the paper describes how they set out to show just how obvious it is. They needed to show the bubbles could be made, that they would work well as a pollinator, and that there was a practical way of controlling them. A ‘proof of concept’ was what they were attempting. This is how they describe the outcome; “…we demonstrate that (1) chemically functionalized soap bubbles exhibit unique properties, such as delivering pollen grains to the targeted flowers in a simple manner, reducing the usage of pollen grains, effectively attaching soap bubbles on the pistils of the targeted flowers using the high stickiness of the soap bubble membrane, preventing severe damage to delicate flowers using the softness and high flexibility of soap bubbles, and enhancing the pollen activity by promoting germination ratio and length of pollen tube; (2) chemically functionalized soap-bubble-mediated pollination can be used for practical Pyrus pyrifolia var. culta pollination at orchards aside from its contribution toward the healthy expression of fertility for various pollen grains; (3) mechanically stabilized soap bubbles capable of withstanding windmills due to robotic pollination can be successfully prepared; and (4) an autonomous controllable unmanned aerial vehicle (UAV) equipped with a mechanically stabilized soap bubble maker can fully automatically transport pollen grains to Lilium japonicum flowers, thus successfully aiding in plant pollination.” These weren’t just any old bubbles. They used a particular surfactant that aided bubble formation, but which did not harm growing pollen tubes, in proportion to the size and number of pollen grains it had to ‘host’ (2000/bubble – 4mg/ml). The liquid was the right pH, with added boron, calcium, magnesium, and potassium salts, proteins from Gelatine, and an inert, cellulose-based viscous polymer (your eye-drops) to fuel germination and control the properties of the bubble membrane. Truly ‘functional’ bubbles. The drone, and the bubble maker, were off-the-shelf toys, although, beyond the ‘proof-of-concept stage, you can imagine them being much more sophisticated, intelligent even. Where will this end up? Probably nowhere, like 99% of such ideas, just creating more ideas. But that 1%? That 1% changes things. Yang and Miyako, Soap Bubble Pollination, iScience (2020), https://doi.org/10.1016/j.isci.2020.101188
  5. I've had a good look through NZ Post and NZ Customs and I can't see anything that restricts personal export of honey, so I'm going to want to see the Regulations to settle the question. Nor do I see the logic of such a restriction. Commercial exports are of course a different matter.
  6. The title caught my eye; I was hoping for rather large suspended copper sculptures buzzing around the building. A great addition to Wellington's public art collection! Oh well...
  7. This isn't an either, or. Both are effective, doing different things under different circumstances, and often used together. It's worth learning how and when to deploy both. The was once a brief craze for a product sold as 'liquid smoke'. It smelt like a terrible Islay, but achieve nothing much as far I could see, but had a ready market amongst the many who seem unable to keep a smoker going. Adding sugar is a bit of a faff; I don't like because it just makes things sticky, but wasps will if you have them. I think people used sugar spays when collecting swarms so they had a mix prepared. If swarms had been out a bit they could be grumpy and spraying them with food lightened their mood. I never found it worthwhile. Stick to plain water, doesn't make the spray bottle horrible either. One more thing. I saw this weeks ago, in the days when we were allowed out to the barbers. It produces a beautiful and long-lasting mist. Apparently available from Wish but I haven't followed that up. Anybody seen or tried it? The hair dresser was unwilling to part with hers and didn't know where I could buy one.
  8. Agreed. It looks like apis predominantly, but without being able to manipulate the focus... if you imagine them as a coffee bean, you get different shaped silhouettes as you rotate around the long axis, and another seen end on. But I wonder if it's important for the average Joe to know, it's all nosema, and the effects are pretty much the same. Sometimes we get lost in the details.
  9. Not much. It's a foliar fert and any problem is likely due to the surficants it contains; by its own account, very effective ones. Needless to say, spraying bees with a surficants is pretty dumb. Because it's not a pesticide, and not toxic, I'd doubt there is much in the way of warnings or controls that apply, but @Don Mac may know more.
  10. 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
  11. 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
  12. Not helpful that the paper sits behind a pay-wall, but I do have a copy. In brief the proposal is that several studies have shown Varroa breeding tanks in high humidity (@ >80%) so modify beehives to be more like natural nests where the humidity (apparently) is high (@80%). Mitchell has done some interesting work modeling airflow in hives (search the Forum) so it's an idea that should be taken seriously, but should still be discussed critically. Most of you probably have an entirely different idea about the value of humidity in a beehive, so that's probably the place to start. BTW Derek Mitchell's work is mentioned in Tom Seeley's new book, but it deals with temperature control, not humility control.
  13. There would be a Trade Descriptions case against this if anyone could be bothered. As the UK will be practically lawless shortly they'd better be quick.
  14. @derekm A few initial thoughts; 1. I knew when I got to the word 'tuple' this read was going to take some effort! 2. This might be the nail in the coffin for the 'heating varroa' advocates. 3. Have there been actual measurements (rather than modeling) of humidity a) in natural nests and b) in the putative 'ideal' man-made nest and do they compare with modeling? 4. I need to read it a few more times.
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