Thiamethoxam-Induced Intergenerational Sublethal Effects on the Life History and Feeding Behavior of Rhopalosiphum padi .

Thiamethoxam, a second-generation neonicotinoid insecticide is widely used for controlling sap-sucking insect pests including Rhopalosiphum padi . The current study aimed to investigate the life-history parameters and feeding behavior of R. padi following treatments with sublethal concentrations of thiamethoxam. The lethal concentration 50 (LC 50 ) value of thiamethoxam against adult R. padi was 11.458 mg L -1 after 48 h exposure. The sublethal concentrations of thiamethoxam (LC 5 and LC 10 ) significantly decreased the adult longevity, fecundity, and reproductive days in the directly exposed aphids (F 0 generation). In the progeny R. padi (F 1 ), the developmental durations and total prereproductive period (TPRP) were decreased while the adult longevity, fecundity, and reproductive days (RP d ) were increased at both thiamethoxam concentrations. The demographic parameters including the net reproductive rate ( R 0 ), intrinsic rate of increase ( r ), and finite rate of increase ( λ ) were prolonged only at the LC 5 of thiamethoxam. The EPG results indicated that the sublethal concentrations of thiamethoxam increases the total duration of non-probing (Np) while reducing the total duration of E2 in directly exposed aphids (F 0 ). Interestingly, the E2 were significantly increased in the progeny generation (F 1 ) descending from previously exposed parental aphids (F 0 ). Overall, this study showed that thiamethoxam exhibited high toxicity against directly exposed individuals (F 0 ), while inducing intergenerational hormetic effects on the progeny generation (F 1 ) of R. padi . These findings provided crucial details about thiamethoxam-induced hormetic effects that might be useful in managing resurgences of this key pest.