Genetics and fitness costs of resistance to flupyradifurone in Bemisia tabaci from China

Flupyradifurone is a promising new insecticide used for controlling Bemisia tabaci during vegetable production. In this study, we assessed the fitness costs and mode of inheritance associated with resistance to flupyradifurone in B. tabaci by comparing the susceptible strain (MED-S) to one field-evolved flupyradifurone-resistant strain (WH-R, with 199-fold resistance) and one laboratory-selected flupyradifurone-resistant strain (FLU-SEL, with 124-fold resistance). Progenies of reciprocal crosses between WH-R and MED-S (F_1A, F_1B, and pooled F₁), and between FLU-SEL and MED-S (F_1C, F_1D, and pooled F₁’), showed varying degrees of dominance, indicating that resistance to flupyradifurone in WH-R was autosomal and incompletely dominant, yet in FLU-SEL it was autosomal and incompletely recessive. Furthermore, the development of resistance to flupyradifurone occurred at the expense of fitness costs for the resistant populations. Compared to the MED-S strain, WH-R showed a relative fitness of 0.50 with significantly prolonged developmental durations and reduced survival rates of the nymphal and pseudopupal stages, as well as decreased fecundity and hatchability. Similarly, FLU-SEL showed a relative fitness of 0.65 and also demonstrated prolonged developmental durations and reduced survival rates of nymphs and pseudopupae, as well as decreased hatchability in comparison with the MED-S strain. However, no significant differences in fecundity were observed between MED-S and FLU-SEL. The present study provides useful knowledge for formulating pest management strategies in the field, which will allow growers to slow the development of resistance to flupyradifurone and to sustainably control B. tabaci.