Work

Fitness Costs of Broflanilide Resistance: Susceptibility, Resistance Risk and Adaptive Trade-Offs in Spodoptera frugiperda

Year: 2026

Type: article

Abstract: The fall armyworm (FAW), Spodoptera frugiperda (Lepidoptera: Noctuidae), is a highly destructive polyphagous pest that threatens a variety of economic crops, and easily and rapidly develop resistance against multiple insecticides. Broflanilide, a novel meta-diamide insecticide, has demonstrated strong efficacy against lepidopteran pests. However, the risk of resistance and fitness costs of FAW against broflanilide remains unclear. Therefore, resistance development was evaluated across nine generations of selection against LC70 of broflanilide by using the diet incorporation method. After nine generations, the LC50 increased from 0.134 to 0.232 mg/kg, indicating an increase of 1.73-fold in resistance. The realized heritability (h2) of resistance was calculated to be 0.084, suggesting a slow rate of resistance evolution. The predicted rate of resistance development suggested that, a 10-fold increase in LC50 would require 30.1 to 66.4 generations using selection mortalities of 90% and 50%, respectively. Fitness costs were assessed using age-stage, two-sex life table analysis. The broflanilide-selected (Brof-SEL) strain showed an increase in larval development, adult longevity, and adult pre-oviposition periods than the wild-type (WT) strain. Meanwhile, female pupal weight and total fecundity were significantly reduced in the Brof-SEL strain. No significant difference was noted in male pupal weight, pupation interval, and oviposition duration. The relative fitness of the Brof-SEL strain was 0.38, indicating notable biological trade-offs. Overall, these findings highlighted a low risk of resistance development and underlined the importance of broflanilide as a sustainable tool in the integrated pest management programs against FAW.

Source: Agronomy

DOI: 10.3390/agronomy16030308