Impact of sublethal and low lethal concentrations of flonicamid on key biological traits and population growth associated genes in melon aphid, Aphis gossypii Glover

Abstract

Flonicamid (N-cyanomethyl-4-trifluoromethylnicotinamide) is a novel systemic insecticide that shows high insecticidal toxicity against sap-sucking pests. However, little is known about the sublethal effects of flonicamid on melon aphid, Aphis gossypii Glover, a serious insect pest of many vegetables. Herein, the toxicity of flonicamid to A. gossypii was determined using the leaf-dipping method, and the sublethal effects of this insecticide on biological traits of A. gossypii were evaluated using age-stage, two-sex life table method. The results showed that the LC50 value of flonicamid to A. gossypii adults was 7.177 mg L−1. The sublethal (LC5) and low lethal (LC15) concentrations of flonicamid reduced the fecundity of the F0 generation aphids. Moreover, the intrinsic rate of increase (r) and finite rate of increase (λ) of F1 generation were also significantly decreased in the flonicamid treatment groups, while the mean generation time (T) of the F1 generation was significantly prolonged compared to the control. In addition, the expression levels of juvenile hormone epoxide hydrolase (JHEH), vitellogenin (Vg), and ultraspiracle protein (USP) significantly increased in surviving adult aphids that were exposed to LC5 and LC15 of flonicamid in the F0 generation. The data demonstrate that sublethal and low lethal concentrations of flonicamid could suppress the growth of A. gossypii, and the differential expression of development- and reproduction-related genes might be involved in the sublethal effects of flonicamid on A. gossypii.