Sublethal effects of synthetic insecticides on life history of Myzus persicae (Sulzer) (Hemiptera, Aphididae) under varying temperatures

Abstract

Myzus persicae (Sulzer) (1776) (Hemiptera: Aphididae) has a wide geographic distribution and is considered a pest of economic importance in several agricultural crops. This work was carried out to investigate how lethal and sublethal exposure of M. persicae to synthetic insecticides (i.e., neonicotinoids, organophosphate, and pyrethroids) together with temperature variation, affect the biological and reproductive traits , and gaining a better understanding of the oxidative stress role in the aphids responses. To this end, we first improved our aphid-rearing protocol by testing the potential use of a hydrogel a rearing substrate. We also determined the concentration-response curves of five insecticides (chlorpyrifos, deltamethrin, thiamethoxam, lambda-cyhalothrin, thiamethoxam + lambda-cyhalothrin, and imidacloprid) for the green aphid under four different temperatures (15, 20, 25, and 28°C). Then, we tested the effect of low concentrations (LC1, LC5, LC10, LC15, LC20, and LC30) of each insecticide on the longevity and fecundity of M. persicae. Subsequently, we evaluated the oxidative stress responses of exposed aphids to different low concentrations of imidacloprid by measuring their malondialdehyde (MDA) and H2O2 contents at different time points (12 and 48 hours). The results showed that colonies of M. persicae can be maintained over time by producing sufficient offspring using hydrogel. Furthermore, the toxicities of the tested chemicals and their stimulatory effect on fecundity and longevity varied according to temperatures. In addition, such variation in hormetic response could be linked, eventhough only partially, to the oxidative stress responses induced by the exposure to low concentrations of insecticides. Therefore, the results obtained here have provided important information on the adaptation mechanisms of these organisms in challenging environments, which will be of paramount importance for the design of management strategies for M. persicae in agroecosystems.