Unraveling the feeding response and intergenerational sublethal effects of flonicamid on Rhopalosiphum padi

Abstract

Flonicamid is a systemic insecticide effective against sap-sucking insect pests, including wheat aphid, Rhopalosiphum padi. However, no research has been conducted on the effects of sublethal concentrations of flonicamid on key demographic parameters and feeding behavior of R. padi. In this study, we examined the sublethal effects of flonicamid on the biological characteristics along with the feeding behavior of R. padi using age-stage, two-sex life table approach, and electrical penetration graphs (EPGs). The toxicity bioassays showed that flonicamid exhibited high toxicity against R. padi adults after 48 h treatment. The adult longevity, fecundity, and reproductive days of the F0 generation were significantly reduced following R. padi exposure to the LC5 and LC10 of flonicamid. Intergenerational sublethal effects of flonicamid were observed on the developmental stages of the progeny generation (F1) such as increased pre-adult stages and decreased longevities. The reproduction and life table parameters, including fecundity, R 0, r, λ, and reproductive days (RP d ) were significantly decreased in F1 generation at both sublethal concentrations of flonicamid as compared to control. Moreover, the EPG data showed that the total duration of phloem sap ingestion and concurrent salivation (E2) were significantly decreased in F0 at both LC5 and LC10, while in F1 generation, the E2 was substantially reduced only at LC10 of flonicamid compared to control. Together, our findings demonstrated that sublethal concentrations of flonicamid negatively affect the demographic parameters and feeding behavior, which consequently inhibit the population growth of R. padi. These sublethal effects are an added benefit to the present mortality effects, which might be crucial in controlling this key pest.