Insecticide Resistance Evolution Negatively Affects the Fitness of Aphis gossypii Glover During Selection on Cotton Plants Under Laboratory Conditions

The cotton aphid, <i>Aphis gossypii</i> Glover, is among the most economically significant sap-sucking insect pests, inflicting substantial economic losses worldwide. Insecticides such as thiamethoxam, bifenthrin, and flonicamid are commonly used to manage this pest, despite the inherent risk of developing resistance. In this study, we investigated the evolution of insecticide resistance in <i>A. gossypii</i> after continuous selection with thiamethoxam, bifenthrin, and flonicamid over more than ten generations in a controlled laboratory environment. We assessed the fitness of resistant strains using an age-stage, two-sex life table approach, comparing them to a susceptible population. The results indicated that <i>A. gossypii</i> achieved resistance levels of 158.60-fold against thiamethoxam, 129.18-fold against bifenthrin, and 104.75-fold against flonicamid. Furthermore, life table analyses revealed that the developmental stages were significantly extended, while longevity decreased in all resistant strains compared to the susceptible population. Additionally, the net reproductive rate (<i>R</i>₀), fecundity, and reproductive days were notably reduced in the resistant cohorts when compared to the susceptible strain. Overall, these findings provide valuable insights into the laboratory-induced evolution of insecticide resistance and the associated fitness costs in <i>A. gossypii</i> when feeding on cotton plants. This information could be instrumental in formulating effective resistance management strategies to control this significant pest.