Sublethal and transgenerational effects of chlorfenapyr on physiological and developmental traits of Spodoptera frugiperda

The fall armyworm (FAW, Spodoptera frugiperda J. E. Smith), is a highly invasive pest causing significant crop yield losses. Chlorfenapyr has been widely utilized in China to control FAW. This study investigated the sublethal and transgenerational effects of chlorfenapyr on FAW to enhance its appropriate utilization. LC10 and LC20 values of chlorfenapyr were estimated to 7.47 and 12.08 μg/g after a 72-hour exposure, respectively. Low chlorfenapyr concentrations extended the duration of larval stage and pre-oviposition period, reducing larvae body weight, pupation rate and eclosion rate in both the F0 and F1 generations. Additionally, such exposure decreased the F0 generation’s mating rate, fecundity, and egg hatching rate. The feeding indicators in third instar larvae from the F0 generation, including relative growth rate (RGR), efficiency of conversion of ingested food (ECI), efficiency of conversion of digested food (ECD), and relative consumption rate (RCR), exhibited significant decrease compared to the control group, while approximate digestibility (AD) was higher. Larvae exposed to LC10 or LC20 exhibited elevated carboxylesterases (CarEs), cytochrome P-450s (P450s), and glutathione S-transferases (GSTs) activities from 12 to 24 hours’ exposure, Notably, GSTs activity was higher at 6-hours compared to the control group, while CarEs and P450s activities significantly decreased. LC20 adversely affected long-term life table parameters of the F1 generation, including intrinsic rate of increase (r), the finite rate of increase (λ), and the net reproductive rate (R0 ). These findings demonstrate that sublethal effects of chlorfenapyr can impair FAW growth and development, impacting the population dynamics of the F1 generation.