Off-Season Diet and Ecology of the Boll Weevil Mediate Its Long-Term Malathion Susceptibility

The cotton boll weevil (Anthonomus grandis grandis) remains one of the most damaging pests of cotton. Its survival between cultivation seasons can influence population growth and insecticide efficacy. In this study, we examined how different off-season food sources affect adult survival and reproduction, and whether boll weevils entering the next planting season are more susceptible to the insecticide malathion after selection pressure is removed. During the off-season, adult females were fed cotton terminals, pollen, or flower buds. Cotton terminals produced the lowest survival rate, whereas pollen and flower buds supported higher survival. Diet did not affect reproductive traits such as copulation or sperm viability; however, females fed flower buds produced more eggs. Boll weevil populations collected after the off-season showed reversion toward susceptibility compared with those collected at the end of the growing season. These findings indicate that lower food availability and reduced insecticide exposure during the off-season may mitigate selection for malathion resistance. Managing residual boll weevil populations during the fallow period is critical for long-term pest control and resistance management in cotton production systems.