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BACKGROUND Cnaphalocrocis medinalis is one of the major rice insect pests in Asia. Chlorantraniliprole is one of the most important insecticides for the control of C. medinalis. In this study, a field-resistant population and a susceptible strain of C. medinalis were used to evaluate the inheritance of chlorantraniliprole resistance and fitness costs in the field. RESULTS The field-resistant population (Cm-RR) showed 128.4-fold resistance to chlorantraniliprole compared with the susceptible strain (Cm-SS). The dose-response of reciprocal cross progeny (F1 and F1') showed no significant difference, which indicated the inheritance of resistance to chlorantraniliprole in C. medinalis was autosomal. The degrees of dominance (D) of resistance for F1 and F1' were -0.19 and -0.05, respectively, indicating that the chlorantraniliprole resistance of C. medinalis was incompletely recessive inheritance. At the same time, significant differences between observed and expected mortalities of self-cross (F2 and F2') and backcross (BC and BC') progenies suggested chlorantraniliprole resistance is controlled by multiple genes. Furthermore, the Cm-RR population had a relative fitness of 0.32 with a substantially decreased pupation rate, emergence rate, fecundity, and substantially increased developmental time of larval and pupa stages. CONCLUSION Current research showed that the inheritance of chlorantraniliprole resistance to C. medinalis was autosomal, incompletely recessive and multigene. The field-resistant population had a relative fitness of 0.32 when compared with the susceptible strain. This study provided valuable information for facilitating the development of chlorantraniliprole resistance management strategies. © 2024 Society of Chemical Industry.