D3354: Differential pesticide sensitivity between Apis cerana and Apis mellifera (Hymenoptera: Apidae) and underlying key molecular factors

In South Korea, two species of honey bees, Apis cerana and Apis mellifera, coexist, exhibiting distinct physiological and toxicological characteristics, particularly in pesticide sensitivities. To specify their different responses to insecticide exposure, this study investigated the acute toxicity represented by LD₅₀ values. For most insecticides, A. cerana showed higher sensitivity compared to A. mellfiera. To elucidate these differences, we conducted comparative analyses of target site sensitivity and metabolic factors between the two species. Comparison of the amino acid sequences of the five major target sites to pesticides did not reveal any apparent differences between A. cerana and A. mellifera, suggesting that variations in target site sensitivity do not account for their differing toxicological responses. However, examination of the expression profiles of several key cytochrome P450s (P450s), which are involved in detoxification or bioactivation, before and after pesticide treatment revealed species-specific expression patterns for some detoxification P450s. This finding suggests that the differential toxicological traits may be attributed to species-specific differences in P450-mediated metabolic factors. Our study represents the first systematic analysis elucidating the molecular basis of differential pesticide sensitivity between these closely related honey bee species, shedding light on crucial aspects of their pesticide susceptibility.