Bioassay based Korean Diamides Resistance Status and Management Strategy of Spodoptera exigua (Lepidoptera: Noctuidae)

초록

Diamide insecticides have been widely used to control lepidopteran pests due to their high efficacy and selectivity, but their intensive and prolonged use has led to the development of resistance in Spodoptera exigua populations in Korea. This study investigated the current status of resistance to chlorantraniliprole in S. exigua, examined potential cross-resistance with flubendiamide, and assessed the inheritance pattern of resistance using hybrid strains. Field populations were collected from 19 locations between 2014 and 2022, and bioassays were conducted with 22 insecticides. Resistance ratios (RRs) were calculated based on the LC50 of a susceptible strain, and F1 and F2 hybrids were generated through reciprocal crosses. The results showed high resistance levels to chlorantraniliprole and flubendiamide, particularly in populations from Yeoju, Jindo, and Gangneung. F2 hybrids exhibited an average mortality rate of only 35.6%, indicating stable inheritance of resistance. Moreover, no statistically significant differences were observed between reciprocal crosses, suggesting that resistance is inherited in an incomplete dominant manner and is likely located on an autosome. While molecular analyses were not performed in this study, previous research has indicated that overexpression of CYP9A40 may play a more critical role in resistance than known RyR mutations such as I4790M. These findings highlight the urgent need for insecticide resistance management (IRM) strategies, including the rotation of insecticides with different modes of action, the use of molecular diagnostics such as LAMP and qRT-PCR for field monitoring, and the integration of alternative compounds like meta-diamides and isoxazolines. A resistance-informed integrated pest management (IPM) approach will be essential to ensure sustainable and effective control of S. exigua.

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