Sublethal effect and detoxifying metabolism of metaflumizone and indoxacarb on the fall armyworm, Spodoptera frugiperda

Abstract

Abstract The fall armyworm (FAW), Spodoptera frugiperda, is a highly polyphagous invasive pest that damages on various crops. Pesticide control is the most common and effective strategy to control of FAW. In this study, we evaluated the toxicity of metaflumizone and indoxacarb against third-instar FAW larvae using the insecticide-incorporated artificial diet method under laboratory conditions. Both metaflumizone and indoxacarb exhibited substantial toxicity against FAW, with LC50 values of 2.43 and 14.66 mg/kg at 72 h, respectively. The sublethal effects of metaflumizone and indoxacarb were investigated by exposing FAW third-instar larvae to LC10 and LC30 concentrations of these insecticides. Sublethal exposure to these two insecticides significantly shortened larval and adult developmental times, extended pupal developmental times, and led to reduced pupal weight, pupation rates, and adult fecundity in the treated parental generation at LC10 or LC30 concentrations, in comparison to the control group. We also assessed he transgenerational sublethal effects, and the findings indicated that metaflumizone and indoxacarb had comparable effects on the F0 generation, except for an observed significant increase in larval developmental time in the F1 generation. Furthermore, Larvae exposed to LC10 or LC30 concentrations of indoxacarb exhibited elevated activity levels of Multifunctional oxidase (MFO) and glutathione S-transferase (GST), which coincides with the observed synergistic effect of PBO and DEM. In conclusion, the high toxicity and negative impact of metaflumizone and indoxacarb on FAW provided significant implications for the rational utilization of insecticides against this pest.