Fluvalinate resistance of Varroa jacobsoni oudemans (Acari: Varroidae) in Mediterranean apiaries of France

For control of Varroa jacobsoni Oudemans, a parasite of the honey bee (Apis mellifera L), we evaluated the level of susceptibility of mite populations to the most common acaricide (fluvalinate). Mortality was recorded after 24 h exposure on the bottom of plastic Petri dishes, treated with different dilutions of the 240 g/L emulsifiable concentrate Klartan(R). The results showed three categories of mite populations: i) susceptible with a LC50 lower than 2 ng/cm(2); ii) populations, with a LC50 ranging from 2 to 20 ng/cm(2), that included some resistant mites; and iii) resistant with a LC50 higher than 20 ng/cm(2). For field surveys of resistance, a 10 ng/cm(2) fluvalinate concentration threshold would allow early resistance detection.