Zachary Huang said: > There is no scientific evidence (yet) that the fluvalinate-resistant > mites are also coumaphos resistant, aside from anecdotal evidence. and he later said, about possible causes of "cross resistance": > One of them is that amitraz might have been used for a quite awhile in US. There is no scientific evidence, nor even anecdotal evidence that amitraz was in use where mites became either resistant or cross-resistant. :) Not to pick on Zach, who deserves kudos for being one of the rare card-carrying researchers who gives us the benefit of his views on this mailing list, but one might tend to get cross when cross-resistance is first dismissed as "anecdotal", and then promptly blamed on the beekeeper, based more upon an absence of specific evidence than any specific supporting facts. If beekeepers reporting problems are going to have dispersions cast upon their character and ethics, beekeepers are going to hesitate to report such problems. I think it should be clear that the mere number of locations where resistant mites of one sort or another have been found is evidence enough that this is a natural result of "by the book" use. As for "cross-resistant" or "multiply resistant" mites, I think that again, the number of sites should prove the point. http://www.apistan.com/newsroom/ABJ_article141-6.htm "A very unexpected result from this study revealed that the use of amitraz seemed to cause fluvalinate resistance to worsen in this varroa population. The explanation for this most likely is that there is cross-resistance between amitraz (a formamidine pesticide) and fluvalinate (a pyrethroid pesticide)-exposure to one affects resistance to that and the other compound. This has been backed up by additional research reports in Florida, which indicate that amitraz does not control fluvalinate- resistant varroa populations. For this reason we do not advocate further research directed at using amitraz to control fluvalinate-resistant varroa." http://groups.yahoo.com/group/Apis_Newsletter/message/14 Nov 2002 APIS "Reports continue of fluvalinate- and coumaphos- resistant Varroa mites around Florida. Beekeepers must continue to monitor their mites or they quickly can get into deep trouble." jim :::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::: -- Visit www.honeybeeworld.com/BEE-L for rules, FAQ and other info --- ::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::