Inheritance of chlorantraniliprole resistance and fitness costs in a field population of Cnaphalocrocis medinalis (Lepidoptera: Pyralidae) in China

BACKGROUND:Cnaphalocrocis medinalisis one of the major rice insect pests in Asia. Chlorantraniliprole is one of the mostimportant insecticides for the control ofC. medinalis. In this study, afield-resistant population and a susceptible strain ofC. medinaliswere used to evaluate the inheritance of chlorantraniliprole resistance andfitness costs in thefield.RESULTS: Thefield-resistant population (Cm-RR) showed 128.4-fold resistance to chlorantraniliprole compared with the suscep-tible strain (Cm-SS). The dose-response of reciprocal cross progeny (F1 and F10) showed no significant difference, which indi-cated the inheritance of resistance to chlorantraniliprole inC. medinaliswas autosomal. The degrees of dominance (D)ofresistance for F1 and F10were-0.19 and-0.05, respectively, indicating that the chlorantraniliprole resistance ofC. medinaliswas incompletely recessive inheritance. At the same time, significant differences between observed and expectedmortalities of self-cross (F2 and F20) and backcross (BC and BC0) progenies suggested chlorantraniliprole resistance is controlledby multiple genes. Furthermore, theCm-RR population had a relativefitness of 0.32 with a substantially decreased pupationrate, emergence rate, fecundity, and substantially increased developmental time of larval and pupa stages.CONCLUSION: Current research showed that the inheritance of chlorantraniliprole resistance toC. medinaliswas autosomal,incompletely recessive and multigene. Thefield-resistant population had a relativefitness of 0.32 when compared with the sus-ceptible strain. This study provided valuable information for facilitating the development of chlorantraniliprole resistancemanagement strategies