Genetic analysis and screening of pyrethroid resistance mutations in Varroa destructor populations from Turkey.

Varroa destructor is the most common ectoparasite of the Western honey bee (Apis mellifera L.) worldwide and poses a serious threat to bee health. Synthetic acaricides, particularly pyrethroids, are frequently used to control Varroa mites. However, long-term and repeated use of synthetic pyrethroids has led to the development of resistance. In this study, we report on the presence of resistance mutations in the voltage-gated sodium channel in V. destructor populations from Turkish beekeeping areas. Two resistance mutations, L925V and L925I, that were previously associated with pyrethroid resistance, were found in more than 75% of the populations. A general correlation between the presence of mutations and the history of acaricide usage was observed for the sampled hives. In addition, we show there is only a low genetic distance among the sampled V. destructor populations, based on the analysis of three mitochondrial genes: cytochrome b (cytb), ATP synthase subunit 6 (atp6), and cytochrome c oxidase subunit III (cox3). Revealing the presence and geographical distribution of pyrethroid resistance mutations in V. destructor populations from Turkish apiaries will contribute to create more effective mite management programmes.