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 (LC ₅₀  = 7.46 mg/L) and notable repellent activity against R. pedestris . Exposure of nymphs to sublethal concentrations (LC ₁₀ and LC ₃₀ ) significantly prolonged nymphal development and the adult preoviposition period, while reducing adult longevity, oviposition duration, and fecundity in the parental (F ₀ ) generation. In addition, LC ₃₀ exposure produced adverse transgenerational effects in the F ₁ generation, including extended adult preoviposition period, decreased male longevity, reduced oviposition duration, fecundity, net reproductive rate ( R ₀ ), intrinsic rate of increase ( r ), and finite rate of increase ( λ ) of the population. Moreover, both LC ₁₀ and LC ₃₀ 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.