Resistance against clothianidin and associated fitness costs in the chive maggot, Bradysia odoriphaga

The chive maggot, Bradysia odoriphaga Yang and Zhang (Diptera: Sciaridae) is an economically important insect pest, affecting many important vegetables, including Chinese chive, especially in northern China. Clothianidin is a second-generation of neonicotinoid insecticide that is currently used for the management of B. odoriphaga. In the present study, we investigated the development of resistance after continuous laboratory selection and associated fitness costs in B. odoriphaga against clothianidin insecticide. The results showed that B. odoriphaga population developed 76-fold resistance, following exposure with clothianidin insecticide for 10 generations. Similarly, life table analysis showed that the fecundity, along with male and female longevity in a resistant strain of B. odoriphaga was decreased significantly compared with the susceptible strain. The developmental duration of larvae and pupae were increased dramatically in the resistant strain, while no effects were observed on egg hatchability. Furthermore, the demographic parameters such as the intrinsic rate of increase (r) (d(-1)), net reproductive rate (R-0) (offspring/individual) and finite rate of increase (lambda) (d(-1)) were found to be significantly decreased in the laboratory selected resistant population when compared with the susceptible strain of B. odoriphaga, in addition, only mean generation time (T) (d) increased significantly. These results suggest that B. odoriphaga responded quickly and develop a high level of resistance against clothianidin insecticide under continuous selection pressure. Additionally, the associated fitness costs may have direct implication for the management of B. odoriphaga against clothianidin.