Effects on Varroa jacobsoni from acaricides in beeswax
Ingemar Fries; Klaus Wallner; Peter Rosenkranz
The effect from acaricide residues in beeswax on mortality and fertility of Varroa jacobsoni was investigated. Amitraz, coumaphos and fluvalinate were added to acaricide-free wax at 0, 1, 10, 100 ppm each and the wax subsequently was used to produce comb foundation. Amitraz could not be recovered from the foundation, but foundation where coumaphos and fluvalinate had been added to the wax contained approximately the added residue levels. When mites were allowed to enter brood in combs made from this foundation, the effect from coumaphos residues was dramatic. Almost all mother mites died in combs where 100 ppm coumaphos had been added to the foundation and increased mother mite mortality occurred at the 10-ppm level. An effect from fluvalinate was only seen in combs drawn from foundation with 100 ppm fluvalinate. If one brood generation had been present prior to the brood attacked by the mites, no harmful effects to mites from wax contaminants were found, even at the highest contamination levels. This result is probably due to the honey bee cocoon acting as a barrier for acaricide transfer from the wax to the mites in the cells. It is concluded that studies of mite fertility probably do not need to consider if the wax is contaminated with up to 10 ppm of fluvalinate. At 100 ppm in the wax the effect from this acaricide on mite performance is detectable but not dramatic. However, comb drawn from foundation having 10 ppm or more coumaphos, and in which no brood was reared, dramatically reduced mother mite survival. Since frozen combs are often used when mite fertility is investigated, coumaphos in the wax may distort results at contamination levels found in European wax.