Risk assessment and resistance inheritance of triflumezopyrim resistance in Laodelphax striatellus

Laodelphax striatellus (Fallén) (Hemiptera: Delphacidae) is one of the most important insect pests of rice, and it has been able to develop strong resistance to many insecticides. Triflumezopyrim, a new type of mesoionic insecticide developed by Corteva Agriscience, showed high biological activity in controlling piercing-sucking insect pests such as planthopper and leafhopper.In this study, we continuously selected a susceptible laboratory stain (Unsel) of L. striatellus for 16 generations by exposing it to triflumezopyrim in the laboratory. A 45.1-fold triflumezopyrim-resistant strain (Tri-sel) was established, in which cross-resistance to nitenpyram and acetamiprid was not detected. The realized heritability (h2 ) of the Tri-sel strain was estimated at 0.13. The mortalities of the testing F1 (the offspring of a cross between Unsel and Tri-sel strains) suggested that the resistance of L. striatellus to triflumezopyrim was autosomal and incompletely dominant, as well as a polygenic inheritance. In addition, the results of synergist experiment showed that P450s potentially contributed to the triflumezopyrim resistance. The activities of detoxification enzymes in the Unsel and Tri-sel strains indicated that the activity of P450s in the Tri-sel strain was significantly increased, consistent with the results of synergist experiments. Furthermore, 12 P450 genes demonstrated significant up-regulation.L. striatellus has a certain risk of resistance to triflumezopyrim after continuous selection. Triflumezopyrim resistance did not result in cross-resistance to neonicotinoid insecticides. The up-regulation of multiple P450 genes may mediate triflumezopyrim resistance in L. striatellus. © 2022 Society of Chemical Industry.