Allen, In a recent communication about the evolution and spread of pyrethroid resistance in Europe the following comment was made: > It is thought that beekeepers in Italy used a liquid agricultural > formulation of Klartan, absorbed on a porous piece of wood or similar > to combat varroa. Because there was no control over the amount (of active ingredient) > applied, this practise inevitably gave rise to resistance, not only to > Klartan, but to the whole class of synthetic pyrethroids including > Bayvarol and Apistan. You replied: >This is often repeated, but is at best an oversimplification, and at worst a lie >that those who sell a penny's worth of chemical for $2 don't mind having >repeated often. That is a glib response, offensive not only to me but to the well-respected bee researchers from Germany, Italy, Switzerland and France as well as the hundreds of beekeepers who carried out the trials which proved this to be the case. Research such as this cannot be dismissed because there was some involvement from a chemical company (Sandoz, as it was). Especially when you don't seem to know or care about the reality of this situation - even 'though I have posted this on the LIST some time ago. I am really surprised at you. The statements which John Burgess mentioned originally are far from rhetoric from a "chemical company". There is solid foundation to these claims. In the early 90's as the then Technical Manager for Sandoz I coordinated an international team of independent, reknown experts on a project lasting 5 years, investigating the emergence of pyrethroid resistance in Europe. It had been openly stated by many people, incuding Sandoz, way before the conception of APISTAN that a pyrethroid-resistant mite strain would inevitably evolve. Klartan/Mavrik was being used for years before APISTAN was developed. Providing there is a lage enough selection pressure and the benefits outweigh the costs, organisms mutate through natural selection. FACT. Any and all treatments to control "pest" populations represent a type of selection pressure. FACT. Because of its many benefits of bee safety, low residue profile, proven low mammalian toxicity profile etc etc Apistan (or illegally Klartan/Mavrik) was and indeed still is the most popular hive treatment for varroa worldwide. Incredible selection pressure. FACT. When the first reports of "Apistan inefficacy" arose in 1992 in Italy, APISTAN had only been in use for one year. In the regions where the "inefficacy was most widely reported APISTAN was not used at all; the agrochemical Klartan, however, had been used for 8 years, on balsa wood, on cloth and anything else to hand. Recipes for using Klartan were common in Europe. In Spain they recommended a 5% soltion in water; in France it was 2% solution. This didn't work in Southern Italy after a while and so the dose was increased to 50% and then in many cases, to 100% neat. Low efficacy after 8 years. FACT. When this inefficacy started to show up in Northern Italy, where APISTAN had been used for just 2 years the cause was not so clear. However, the Italians were able to trace exactly the spread of a resistant strain of varroa along the main routes of migratory beekeeping from the North to the South of Italy. Colonies are taken to the South for the winter and brought back North in Spring, carrying with them the resistant varroa from the South. FACT. It is noone's fault that resistant varroa emerged, it is a natural process of evolution. The uncontrolled dosing did however greatly speed up the process. If there is an increase in the LD50 (the level of a substance that wil kill 50% of a population) by tenfold, ie a resistance factor of 10, generally one can say that a resistant strain has emerged. In the case of varroa from Southern Italy the resistance factor was more than 400. Definately resistant. It was also shown scientifically that this resistance is conferred to other related pyrethroids such as flumethrin and acrinathrin. FACT. The dose/response curves obtained for this resistant strain are distinct. Wherever resistance was monitored throughout Italy and later in France, Germany, Switzerland, Austria and Eastern Europe. the exact same curves are characteristic. This most probably means that the resistance has arisen only once in Europe and spread from one focal point. The slow speed of apparition in neighbouring countries suggests Italy to be the focal point. If the dose/response curves were markedly different for the different populations examined then we could expect there to have been separate evolution. So far all populations examined (coordinated by Vita since 1997) have shown the same pattern and seem then to have the same origin. There will always be a risk of any pest organism developing resistance to the treatment. It is why several different types of treatment should be used. If there is resistance to one treatment, perhaps the second or third [different] treatment will take out the resistant individuals. Even IPM will not stop the phenomenon of mutation and evolution in pest populations but the aim is to keep the resistance to a manageable level, below the economic damage threshold. Vita (Europe) Limited is a small UK company specialising in the development of honeybee disease treatments. We take the concept of IPM very seriously and unlike the chemical giants who have no time for such small markets, we are dedicated to improving the health of honeybee colonies, operating world-wide. Yes, we make and sell APISTAN but we also have other treatments in registration and in development, many of them natural agents, for EFB, AFB, mites, chalkbrood and wax moth. In science and in business I believe there is no room for half-truths. At Vita our policy is to be open so as to avoid confusion. While many people may disagree with what we're doing, Vita is not in the business of making a fast buck. What we do is thoroughly researched and is for the long-term. No short cuts, no "oversimplifications". Whatever is posted to the LIST from Vita, we believe to be correct and true. But, Hey, how can this possibly be true - Vita must be classed as a "chemical company", right? Believe what you will. Max Dr Max Watkins Vita (Europe) Limited Brook House, Alencon Link Basingstoke, Hants RG21 7RD UK Tel. +44 (0) 1256 473177 Fax +44 (0) 1256 473179 http://www.vita.demon.co.uk