Detection of insecticide resistance in Bradysia odoriphaga Yang et Zhang (Diptera: Sciaridae) in China

Bradysia odoriphaga Yang et Zhang is a destructive insect pest of Chinese chives. To understand the current status of insecticide resistance of B. odoriphaga in China, the sensitivity variation of eight field populations to six commonly used insecticides, including chlorpyrifos, phoxim, imidacloprid, thiamethoxam, clothianidin and beta-cypermethrin were evaluated. The results showed that almost all the tested B. odoriphaga populations had developed moderate to high resistance to chlorpyrifos and phoxim. There were different resistance levels found in the eight field populations among the three neonicotinoids, imidacloprid, thiamethoxam and clothianidin. Imidacloprid was very effective against B. odoriphaga in most tested populations except those from Yangzhou (10.35-fold) and Tangshan (14.56-fold). While four populations kept susceptible to thiamethoxam, the other four populations showed decreased susceptibility or low resistance. To clothianidin, five populations displayed moderate resistance, two populations displayed low resistance, and one population exhibited susceptibility, respectively. All the tested populations were resistance to beta-cypermethrin, the highest resistance was found in the Tangshan population with a resistance ratio of 172.56-fold. The results of this study provided valuable information for choosing insecticides for control and integrated resistance management of B. odoriphaga.