Decreased cuticular penetration minimizes the impact of the pyrethroid insecticide λ-cyhalothrin on the insect predator Eocanthecona furcellata

Abstract

The use of broad-spectrum pesticides may reduce the biological control efficacy of predatory arthropods. Hence, the risks of pesticides to predators need to be evaluated. Here, we assessed the effects of a broad spectrum pyrethroid λ-cyhalothrin on a polyphagous predatory insect Eocanthecona furcellata via contact exposure route. The recommended application rate of λ-cyhalothrin was lower than the LR50 and HQ (in-field) was equal to 0.57, indicating the risk of λ-cyhalothrin to E. furcellata was low. Dried λ-cyhalothrin residue had no effect on the mortality, body weight, protein content of cuticle, or activities of major detoxification enzymes in E. furcellata. Residual of λ-cyhalothrin was only detected in the cuticle and legs of E. furcellata with a decreasing trend as time went by and no λ-cyhalothrin was detected inside the body. Additionally, a comparative transcriptome analysis was conducted to study global changes in gene expression in E. furcellata at different time points following exposure to λ-cyhalothrin-contaminated environment. A total of 57,839 unigenes with an average length of 1044 bp and an N50 of 1820 bp were obtained. In total, 118 and 109 differentially expressed genes (DEGs) at 12 h, and 60 h were identified between two groups. The DEGs were largely enriched in functional categories related to the structural constituent of cuticle. Accordingly, multiple cuticle protein-coding genes were up-regulated at 12 h after pesticide exposure. The present study stressed the importance of evaluating the compatibility between a specific pesticide (λ-cyhalothrin) and E. furcellata via simulating the releasing predators after insecticide application. The data could help optimize the pesticide use, optimizing the ecological services of E. furcellata as a BCA, and expanding its use into more areas of agriculture.