Discrimination concentrations of acaricides for identification of Varroa destructor resistance in vitro.
1Bee Research Institute Dol, Dol 94, Libcice nad Vltavou 252 66, Czech Republic
2Department of Microbiology, Nutrition and Dietetics, Czech University of Life Sciences Prague, Kamycka 129, 165 21 Prague 6-Suchdol, Czech Republic
3Crop Research Institute, Drnovská 507, Prague 6 - Ruzyne, Czech Republic
Although honeybee parasitic mite V. destructor is present in Europe around 3 decades, synthetic acaricides are widely used. We propose to test mite populations to distinguish sensitive and resistant populations to different active substance for successful treatments.
We adapted plastic vial bioassay for identification of resistant populations of V. destructor in the Czech Republic. The sensitivity of three different Czech varroa mites populations to tau-fluvalinate, acrinathrin and amitraz were observed in vial bioassay. The acaricidal compounds were diluted in acetone and applied to the vials. The females of varroa mites from infested larvae and pupae were added into vials. The mortality of mites was checked after 24 hours of exposition. The populations of mites differed in their sensitivity to three tested acaricidal compounds: pyrethroids acrinathrin and tau-fluvalinate; and formamidine amitraz.
Kyvalka population was resistant to acrinathrin, tau-fluvalinate and amitraz, while Postrizin were sensitive to all acaricides in vitro. The intermediate situation was in Prelovice population, where the mites were sensitive to acrinathrin and amitraz, but not to tau-fluvalinate. When LC50 concentrations for acaricides were compared, sensitive population (Postrizin) has 85, 91 and 31 times lower concentrations than resistant population (Kyvalka) for tau-fluvalinate, acrinatrin and amitraz, respectively. The suggested discrimination concentrations are following: 1, 0.3 and 0.2 µg/mL for tau-fluvalinate, acrinathrin and amitraz, respectively. The application of discrimination concentrations could help for early detection of varroa resistant populations.
The study is supported by the project QJ1530148 of the Czech Ministry of Agriculture.