The lethal and sublethal effects of synthetic miticide tau-fluvalinate (tech.) on adult honeybees

Pyrethroids (e.g., flumethrin and tau-fluvalinate) are frequently related to long half-life inside the hive matrices, which may adversely affect the health of bee colony. In this study we assessed potential harmful lethal and sublethal effects of synthetic miticide tau-fluvalinate (tech.) on winter adult honeybees according to OECD 245 (2017). In vitro reared winter honeybees showed no dose-dependent mortality after the oral 10-days exposure to sucrose solution (50% w/w) spiked with a maximum concentration of 750 μg tau-fluvalinate /kg diet; the No Observed Effect Concentration (NOEC) appears to be higher than or equal 750 μg a.i./kg diet. The results of tau-fluvalinate testing for the sublethal effects on bee immune system showed up-regulated gene expression for abaecin, lysozyme, and defensin in the test groups (1/1 FLU and/or 1/10 FLU), however the expression of hymenoptaecin gene was reduced.