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 (LC₅₀) value of thiamethoxam against adult R. padi was 11.458 mg L⁻¹ after 48 h exposure. The sublethal concentrations of thiamethoxam (LC₅ and LC₁₀) significantly decreased the adult longevity, fecundity, and reproductive days in the directly exposed aphids (F₀ generation). In the progeny R. padi (F₁), 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 (R₀), intrinsic rate of increase (r), and finite rate of increase (λ) were prolonged only at the LC₅ 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 (F₀). Interestingly, the E2 were significantly increased in the progeny generation (F₁) descending from previously exposed parental aphids (F₀). Overall, this study showed that thiamethoxam exhibited high toxicity against directly exposed individuals (F₀), while inducing intergenerational hormetic effects on the progeny generation (F₁) of R. padi. These findings provided crucial details about thiamethoxam-induced hormetic effects that might be useful in managing resurgences of this key pest. [ABSTRACT FROM AUTHOR]