Demographic Responses of Rhopalosiphum maidis to Multigenerational Sublethal Imidacloprid Exposure Under Different Temperature Conditions

The corn leaf aphid, Rhopalosiphum maidis (Fitch), is an important maize pest that causes damage through direct feeding and the transmission of plant viruses. Although sublethal imidacloprid exposure can affect aphid life-history traits, its demographic consequences across generations under different thermal conditions remain incompletely understood. In this study, the LC10 of imidacloprid for adult R. maidis was determined at 25 °C, and the resulting concentration (0.009 mg L−1) was used in exposure experiments conducted at 15, 25, and 35 °C. The demographic performance of the F2 generation was evaluated using age-stage, two-sex life-table analysis following imidacloprid exposure of the F0 and F1 generations. Mean fecundity was lower in the imidacloprid-treated groups than in the corresponding controls at 15, 25, and 35 °C, decreasing from 38.64 to 31.84, from 51.70 to 43.24, and from 28.64 to 23.47 offspring per female, respectively. The net reproductive rate also showed lower reported values in the treated groups at all three temperatures. Differences in the intrinsic and finite rates of increase varied among temperature–treatment combinations, while mean generation time showed no consistent response. Overall, multigenerational sublethal imidacloprid exposure was associated with changes in the demographic performance of R. maidis under the tested thermal conditions. Because the same nominal concentration was used at all temperatures and a statistically significant temperature × insecticide interaction was not established, the observed differences should not be interpreted as evidence that temperature amplified or buffered insecticide effects. These findings highlight the importance of considering thermal conditions when evaluating the demographic consequences of sublethal insecticide exposure.