Sublethal Effects of Abamectin on the Detoxification Enzyme System, Growth, and Reproduction of Cylas formicarius (Fabricius)

Cylas formicarius (Fabricius, 1798) (Coleoptera: Brentidae), the sweetpotato weevil, is an important quarantine pest in sweetpotato production. Exploring the detoxification enzyme responses of pests under pesticide stress helps to clarify the physiological mechanism of pesticide tolerance. Meanwhile, evaluating sublethal pesticide effects on population life tables is critical for revealing transgenerational ecological risks and guiding sustainable pest management. In this study, we analyzed how abamectin affected detoxification enzyme systems, fecundity, growth, and development of C. formicarius. The sweetpotato root-dipping method was used to assess the 48 h toxicity of abamectin to C. formicarius adults. The adult C. formicarius had LC10 and LC30 values of 0.645 and 1.709 mg/L, respectively. Sublethal abamectin induced significant temporal alterations in CarE, GST, and CYP450 activities in C. formicarius. The three detoxification enzymes exhibited distinct dynamic trends and divergent induction or inhibition responses under LC10 and LC30 stress, showing clear temporal specificity. The oviposition period, adult longevity, and fecundity of the parental generation were significantly reduced by sublethal abamectin. In the F1 generation, developmental periods of eggs, larvae, and pupae were longer, whereas adult longevity and total lifespan were shorter than those of the control, and fecundity was also markedly decreased. These results demonstrate that changes in detoxification enzyme activities constitute an important physiological response of C. formicarius under abamectin stress. Population life-table analysis further confirmed the transgenerational inhibitory impacts of sublethal abamectin on weevil population performance. Combining physiological enzyme assays with population life-table evaluation helps us comprehensively understand sublethal risks of this insecticide; this work provides a theoretical basis for rational field application and long-term sustainable management of C. formicarius.