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Dave Black

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Dave Black last won the day on November 8 2017

Dave Black had the most liked content!

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About Dave Black

  • Rank
    Guard Bee


  • DECA Holder
  • Beekeeping Experience
    Hobby Beekeeper


  • Location
    Bay of Plenty

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  1. Dave Black

    Nutritional supplements

    I developed a comparison between a couple of the supplements I was interested at the time (a liquid and a powder), and what I could find in the literature about honey bee requirements (sources like de-Groot, and Filipiak (2017)). It was a bit tricky getting a definitive list of the contents of the products (commercially sensitive apparently), and what we know about honey bee nutrition is still in ‘probably’ territory, but there are a couple of comments to make. I was able to compare around 40 minerals and amino acids. I also can’t say I’m particularly confident that the contents of the products will be the same every time, but let’s hope so. Compared with the ‘real thing’ (esp.pollen) often critical ingredients were missing, or not available in sufficient quantity to be useful. Conversely, one or two ingredients were not needed at all. For a couple of minerals, it’s difficult to be sure but I’d argue they were uncomfortably close to the point of becoming toxic. Iodine and sodium for instance. The dietary requirement varies between caste, developmental stage, locale, and actually season. Just think about the implications of that for a moment. In real life honey bees appear to actively search out the missing mineral elements when they need them, although there isn’t much evidence they can do that with amino acids. Beekeepers getting colonies ready to work out of season or in different/distant geographies –essentially ‘cheating nature’, might have a need to intervene. Some sedentary beekeepers might have local temporal shortages to overcome, and some, chasing monocultures, might need some respite care. None of that applied to me so I decided to leave well alone for now.
  2. Dave Black

    Varroa resistance to Oxalic

    Nanetti, (referred to above) tells you.
  3. Dave Black

    Varroa resistance to Oxalic

    Nope, unless you mean the next generation becomes contaminated by residue from the treatment too. Most of it has gone in a fortnight, but a little remains up to a month, and a tiny bit a little longer. If you dose once a week, you will have more in the hive than you think.
  4. Dave Black

    Varroa resistance to Oxalic

    Not big on the anvil hypothesis myself. 😊 Oxalic acid is found in many living things; pretty ubiquitous. It is an inescapable part of their metabolic processes, even if they didn’t eat it they would make it, just like us. Consequently, nearly everything has a way of getting rid of it. Sometimes this is quite ingenious, some plants produce spiky calcium oxalate crystals that make their leaves unpleasant to eat for example. Sometimes it’s just converted to carbon dioxide and water or passed as is. People make kidney stones if they have trouble getting rid of it. Goats have gut bacteria that help if I remember right, so they can eat some pretty inedible plants. Or, to put it another way, almost everything is probably resistant to oxalic already. I suspect it’s not what it is, but how much of it you get relative to an ability to process it that leads to trouble. In just the way that bees tolerate it, mites could, if they didn’t get such a humungous dose. Until we know how it works, we can’t make sensible guesses. I think the smart money reckons it isn’t acidification of the bee’s haemolymph, because it isn’t a big enough change in pH. It appears to act directly on the mite, perhaps through its feet. Maybe it interferes with calcium ion use and limits energy production, who knows, the possibilities are many, both crude and subtle.
  5. Dave Black

    Varroa resistance to Oxalic

    In 'continuous' treatments I'm less concerned about the mites; more concerned about the 'bees. Eight treatments of 4%sol per year seems a lot. For example: Higes, M., Meana, A., Llorente, J., & Suárez, M. (1999). Negative long-term effects on bee colonies treated with oxalic acid against Varroa jacobsoni Oud . Apidodologie, 30, 289–292. Abstract - Two oxalic acid treatments were given to five colonies in autumn and five colonies in spring. In each treatment, colonies were treated every 7 days for 4 weeks with a 3 % sprayed oxalic acid. Another five colonies in each season served as controls and were sprayed only with water. Efficacy of oxalic acid in autumn was 94 % and in spring was 73 %. A long-term study of the colonies for 3-4 months after the last application of oxalic acid showed a statistically significant negative effect of the acid on brood development. In addition, three queens died in the treated colonies. Rademacher, E., Harz, M., & Schneider, S. (2017). Effects of Oxalic Acid on Apis mellifera. Insects, 8(84). https://doi.org/10.3390/insects8030084 Our aim was to define the no observed adverse effect level (NOAEL) and the lowest observed adverse effect levels (LOAEL) for OAD, including a safety margin for the dosage used in practical beekeeping. Furthermore, we wanted to understand which sublethal effects can be found and how OAD is distributed in the colony. Two honey bee nucleus colonies (A. m. carnica) were used for a distribution test with a macro-computed tomography scanner (macroCT) where OAD (Oxalic acid dehydrate) was mixed with the water-soluble contrast agent Unilux. After oral application, bee mortality occurred at relatively low concentrations (No Observed Adverse Effect Level (NOAEL) 50 µg/bee; Lowest Observed Adverse Effect Level (LOAEL) 75 µg/bee) compared to the dermal treatment (NOAEL 212.5 µg/bee; LOAEL 250 µg/bee). The dosage used in regular treatment via dermal application (circa 175 µg/bee) is below the LOAEL, referring to mortality derived in the laboratory…OAD used to treat varroosis of A. mellifera shows a rapid and consistent distribution in the colony for at least up to 14 days, and high efficacy against the mite, but also lethal and sub-lethal effects. In practical beekeeping, appropriate use of OAD (one topical application, on average 175 µg/bee) is relatively safe for A. mellifera at the colony level, even when some individuals are lost. However, ingestion leads to high mortality. OAD is one of the most important organic acids used for the control of V. destructor. It is indispensable but must be dosed precisely and applied as seldom as possible to prevent sublethal damages which eventually lead to the loss of bees. Long disposition in the bee hive can cause accumulation of the acid and therefore induce further damage. Strachecka, A., Paleolog, J., Olszewski, K., & Borsuk, G. (2012). Influence of Amitraz and Oxalic Acid on the Cuticle Proteolytic System of Apis mellifera L. Workers, 821–832. https://doi.org/10.3390/insects3030821 Oxalic reduced the activity of anti-pathogen cuticle barrier leaving the bees more susceptible to bacterial and fungal pathogens… The rinsings from the body surface of workers in the control group showed activity in relation to all the microorganisms. In bees treated with amitraz and oxalic acid, no activity towards A. niger or S. aureus was observed. Moreover, after applying oxalic acid, no activity was identified in relation to S. typhimurium or P. aeruginosa. Nanetti, A., Bartolomei, P., Bellato, S., De Salvio, M., Gattavecchia, E., & Ghini, S. (2003). Pharmacodynamics of oxalic acid in the honey bee colony. Standing Commision on Bee Pathology. …a noticeable contamination of the adult honey bees was detected 24 hours after the 1999 treatment. One day later the peak reached a maximum of 118 µg/g, but further remarkable decreases occurred on the seventh and on the eleventh days when contents of 10,8 and 2,0 µg/g were found. If an average honey bee weight of about 100 mg is taken as a reference, the individual oxalic acid contamination ranged around 12 µg, 1 µg and 0,2 µg, respectively. Further gradual decrease occurred during the following months… In the second replicate the presence of 14C-oxalic acid could be demonstrated in the honey bee haemolymph. The highest value (10 ng/mg) was recorded 12 hours after the treatment, but a steep decrease occurred further, leading to a concentration of 1,1 ng/mg on the 84th hour. Radioactivity almost completely faded out about one month after the treatment. Little difference, if any, was shown by the autoradiographies of unwashed wings and of the wings where oxalic acid was removed by thorough washing. Both left clear impression of their nervatures on the film. This seems to indicate a low external contamination of the bees and is consistent with the detection of contaminating oxalic acid in the haemolymph, which fills the wing nervatures. .. Twelve hours after the treatment, all the tracts between honey sac and rectum showed the presence of the marker, but later on only occasional presence of the radioactive marker was detected within the honey sacs. Generally the contamination decreased with the time; the intestines collected on the 22nd and 31st days were not contaminated with detectable amounts.
  6. Dave Black

    Show Your Truck

    Six cylinder, 50bhp. Love it. Practically mint too in comparison...
  7. Dave Black

    Science and research in Apiculture

    Yes, it uses the Morrissey study from 2015
  8. Dave Black

    Science and research in Apiculture

    Yes, tracing was what I was interested, both large scale (history) and small scale (epidemiological). The study referenced below collected isolates from 38 countries all over the world, 16 from here. Most were ERIC I (15) and one was ERIC II. More usefully there were 6 sequence types, of which 11 were ST5 ERIC I. This was the kind of work I was looking for. Not sure about it's resolution from an epidemiological view; guess it depends on what you're trying to do. Morrissey, B. J., Helgason, T., Poppinga, L., Funfhaus, A., Genersch, E., & Budge, G. E. (2015). Biogeography of Paenibacillus larvae, the causative agent of American foulbrood, using a new multilocus sequence typing scheme. Environmental Microbiology, 17(4), 1414–1424. https://doi.org/10.1111/1462-2920.12625 I haven't heard of that, finding an ERIC II here was a bit surprising, maybe that was it?
  9. Dave Black

    NZBF Bayvoral: mixed success

    I'd think so. Maybe. In theory brood is produced continuously, but the queen's laying may change in response to food supply, so maybe there were peaks of brood production. We can't know. It's a good way, but closely aligned to the state of the hive rather than the state of the infestation. To make the most of it you need to be able to estimate bee population, brood coverage, and the like. Colonies are not alike either, so makes comparisons difficult. You would have no way of giving me an infestation rate or density for example, and we think 'density' is an important feature of varroa infestations.
  10. Dave Black

    Science and research in Apiculture

    Don't worry @JohnF, I've answered my own question. Surprising what you can do with time to spend...
  11. Dave Black

    Science and research in Apiculture

    Did you find out during any of that work if NZ is home to ERIC I, ERIC II, or a mixture? Maybe you didn't need to know. I can't remember why I wanted to know that but it was very important at the time...
  12. Dave Black

    NZBF Bayvoral: mixed success

    @BeeBob This is a nice, dedicated piece of work. It’s interesting (and lucky) the two colonies are almost opposite in their response. ‘A’ had a larger initial mite mortality which tailed off over the treatment period; ‘B’ had a smaller response at first but mortality in the second ‘half’ of the treatment time was greater than A’s. There will be many potential differences between the two, but a significant one may have been the amount of sealed brood. The first ‘kill’ is of mites on bees, once they are gone it’s of mite emerging from sealed brood cells. From the data we can speculate that A, relative to B, had a higher proportion of bees than brood, and B relatively more brood than bees. Have you the patience to carry on over winter?
  13. Dave Black

    Cow farmers AFB moment

    The painted apple moth, I think that's appeared several times. @JohnF might be thinking of the Queensland fruit fly. There are other current ones like the Pea Weevil, Velevetleaf, Casebearer moth, Bonamia ostreae, Red-vented bulbul, Black grass, and Fire ants. Not sure if Kauri die-back counts, and let's not think about all the marine visitors, or the viruses and bacteria that rain out of the sky (800 million per square meter each day apparently). Being realistic, my guess is that MPI's function is largely to minimise any economic effects rather anything else. And they make 'mistakes' (like Bonamia). @JohnF Mycoplasmas are quite unusual things to deal with aren't they? Funny cell membranes and weird metabolism for instance.
  14. Dave Black

    Cow farmers AFB moment

    Can anyone suggest an example where, after a prolonged period of hand-wringing over some biosecurity incursion, our government minders haven't just thrown in the towel and said 'Nothing more we can do lads, just get on with it.' Any example?
  15. Two year's experience Daley? 😉 The study seems to be saying the 'save-the-bees' crowd could be responsible for the very statistics they abor. As many beekeepers have been saying.