Lethal and sublethal influence of triflumezopyrim on life history traits and enzyme activities in the bean bug, Riptortus pedestris (Hemiptera: Alydidae)

Riptortus pedestris (Fab.) is an important soybean pest in East Asia, where its piercing-sucking feeding behavior leads to soybean syndrome. Triflumezopyrim, a novel mesoionic insecticide, has been widely applied to control sap-sucking insects. However, its lethal and sublethal impacts on R. pedestris remain poorly understood. This study investigated the lethal and sublethal effects of triflumezopyrim on R. pedestris using bioassays, age-stage two-sex life table analyses, and enzyme activity measurements. Results demonstrated that triflumezopyrim exhibited strong toxicity (LC50 = 7.46 mg/L) and notable repellent activity against R. pedestris. Exposure of nymphs to sublethal concentrations (LC10 and LC30) significantly prolonged nymphal development and the adult preoviposition period, while reducing adult longevity, oviposition duration, and fecundity in the parental (F0) generation. In addition, LC30 exposure produced adverse transgenerational effects in the F1 generation, including extended adult preoviposition period, decreased male longevity, reduced oviposition duration, fecundity, net reproductive rate (R0), intrinsic rate of increase (r), and finite rate of increase (λ) of the population. Moreover, both LC10 and LC30 treatments led to substantial elevation in the activities of antioxidant (superoxide dismutase and peroxidase) and detoxification (multifunctional oxidase and glutathione S-transferase) enzymes. These findings indicate that triflumezopyrim exerts strong acute toxicity and pronounced sublethal inhibitory effects on R. pedestris, ultimately suppressing population growth potential. This study offers a scientific basis for the rational use of triflumezopyrim as well as the development of strategies for the management of this species.