>> The key point about "IPM" is that one >> must know pest population in terms of >> how much damage the pests will do. >> The dead-giveaway with varroa is that >> their population growth starts to "go >> exponential" or "spike", and the resulting >> increased population of mites is what >> "overpowers" a colony." > Is this strictly true as written? Yep. The "slope of the curve" is the only practical way to accurately monitoring mite populations, assuming that one would rather use a sticky board alone than both count both mites and estimate bee population for each hive monitored. I'd submit that trying to estimate bee population is counter- productive to the process, and one is better served to spend the time counting mites more often and with more care, ignoring the bee population entirely. Anyone who expresses a threshold as an arbitrary integer is talking down their nose to you, and thinks that you are too stupid to comprehend, or too lazy to make multiple measurements over time. The dead giveaway is when all the handwaving starts about "strong" versus "weak" colonies, rendering the integer not only useless, but misleading, and thereby, counterproductive. > European researchers seem to say it is not generally the > mites that cause colony collapse (bees are weakened but not killed ) > but the associated increase in viruses. This is true. Mark Feldlaufer of the USDA Beltsville Bee Lab recently hired on Judy Chen, an card-carrying microbiologist, who promptly sat down at the keyboard of a PCR machine, and started looking for viruses in individual mites on individual bees, and gathered data that shows a direct correlation between the number of mites on a bee larvae and the incidence of virus transmission between all the mites. The poor little mites are infected THROUGH the bee. The paper is still "in the mill", but has the title: "Molecular evidence for transmission of Kashmir bee virus in honey bee colonies by ectoparasitic mite, Varroa destructor." It will be in "Apidologie". No idea when. Its "in press". The authors are Chen, Pettis, Evans, Kramer, Feldlaufer. The interesting thing was that by the time one had 4 mites crawling into a brood cell, the game was over, in that there was a 100% chance of all 4 mites (and the bee larvae) exiting the cell with viruses, with the mites presumably going on to spread the virus(es) to more mites via bees, and so on. Very impressive, to be able to detect viruses in a single mite at a time. (Mark brought a nice set of slides on this at the last MD/VA joint meeting of the beekeepers.) > It has been posted that mite populations are larger in large > colonies. Is that true? It cannot be true in ALL cases, as it is certainly possible to have a large colony with no mites at all. It is correct to say that a larger colony can "carry" a larger number of mites as an insignificant fraction of what would prompt treatment, and that this same exact number of mites might prompt treatment in a smaller colony. > The concepts of economic threshold and economic injury level > are interesting but are these the most helpful for beekeepers? > Economic Injury level suggests we wait until the reduction in > injury exceeds the cost of treatment - but that could apply > when injury has reached a high absolute level... One must still factor in the reproductive ability of the current population and the future impact thereof. Its not like one is expected to wear blinders to the future. > Do we not need to consider the 'most cost-effective intervention'. The big decision is pulling colonies out of production to treat them (or using Sucrose Octanate, if one has a free afternoon to treat a mere dozen colonies). In some cases, a true hardnosed "Cost effective" strategy may be deciding that the colony is doomed, yet leaving it in production, based upon the premise that the honey harvested will more than pay for a new queen to head up a split made from a healthy colony. The problem is that letting the colony collapse isn't really "keeping" the bees, is it? jim (The power of accurate observation is often called cynicism by those who lack it.) :::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::: -- Visit www.honeybeeworld.com/BEE-L for rules, FAQ and other info --- ::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::