hi all! A few more remarks on the resistancy of Varroa mites to fluvalinate ( Apistan) and flumethril (Bayvarol), seem in order: 1. as has been established on several occasions( cf. a.o. my previous message on this theme), colonies in northern Italy have in fact shown a reduced sensitivity to Apistan strips, while this seems also to be the case for Bayvarol strips. This has obviously to do with the resemblance in molecular structure of both active ingredients. They both belong to the same group of Pyrethroids. It follows, that in order to prevent inducing resistance in V. Mites to either acaricide, it is better policy to implement a mite control scheme based on one of these pyrethroids alternating with a totally different chemical treatment, such as formic- or lactic acid. Alternating two chemicals from the same group would merely enhance general resistance to the group as a whole. 2. If I remember correctly from my days in molecular genetics, resistancy resides in small circular pieces of DNA, called 'resistancy factors' . These minute pieces of genetic information contain the genes involved in resistancy against e.g. a certain chemical, and they can be passed on from one individual to rthe next and so spread much like virus particles. This is one asdon why we have a shared responsability not to bring these resistancy factors into existence, after which they'd 'infect' every other beecolony on earth. This 'epidemy' of resistance would obviously make it very hard to control mites any more thereafter.. sincerely, Hugo -- Hugo Veerkamp ------------------------------------------------------------------- | Email: BEENET INTERNATIONAL | | [log in to unmask] | mail : the Bee bbs | | | P.O. BOX 51008 | | | 1007EA AMSTERDAM | | | The Netherlands | | Beenet : 240:31/0 | modem: +31 20 6764105 | | Fidonet: 2:2801/28 | voice: +31 20 6715663 | ------------------------------------------------------------------ V.Mites from