Transcriptome Analysis to Identify Responsive Genes under Sublethal Concentration of Bifenazate in the Diamondback Moth, Plutella xylostella (Linnaeus, 1758) (Lepidoptera: Plutellidae)

Abstract

Bifenazate is a novel acaricide that has been widely used to control spider mites. Interestingly, we found bifenazate had a biological activity against the diamondback moth (Plutella xylostella), one of the most economically important pests on crucifer crops around the world. However, the molecular mechanisms underlying the response of P. xylostella to bifenazate treatment are not clear. In this study, we first estimated the LC30 dose of bifenazate for third-instar P. xylostella larvae. Then, in order to identify genes that respond to the treatment of this insecticide, the comparative transcriptome profiles were used to analyze the gene expression changes in P. xylostella larvae after exposure to LC30 of bifenazate. In total, 757 differentially expressed genes (DEGs) between bifenazate-treated and control P. xylostella larvae were identified, in which 526 and 231 genes were up-regulated and down-regulated, respectively. The further Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that the xenobiotics metabolisms pathway was significantly enriched, with ten detoxifying enzyme genes (four P450s, five glutathione S-transferases (GSTs), and one UDP-Glucuronosyltransferase (UGT)) were up-regulated, and their expression patterns were validated by qRT-PCR as well. Interestingly, the present results showed that 17 cuticular protein (CP) genes were also remarkably up-regulated, including 15 CPR family genes. Additionally, the oxidative phosphorylation pathway was found to be activated with eight mitochondrial genes up-regulated in bifenazate-treated larvae. In contrast, we found some genes that were involved in tyrosine metabolism and purine pathways were down-regulated, indicating these two pathways of bifenazate-exposed larvae were significantly inhibited. In conclusion, the present study would help us to better understand the molecular mechanisms of sublethal doses of bifenazate detoxification and action in P. xylostella.

Baseline Susceptibility, Cross-Resistance, and Sublethal Effects of Broflanilide, a Novel Meta-Diamide Pesticide, in Spodoptera litura

“…In B. tabaci , treatment with the LC 25 dose of β-asarone (a plant-derived potential insecticide) significantly induces P450 activity, and a sublethal concentration of afidopyropen enhances GST activity [ 18 , 42 ]; in contrast, GST activity is significantly inhibited in Panonychus citri treated with sublethal concentrations of the acaricides fenazaquin and acequinocyl [ 43 ]. Based on the RNA-seq technology, recent studies have suggested that the mechanisms of insecticide sublethal effects are strongly associated with detoxifying gene expression, and those results indicate that cytochrome P450 monooxygenases, esterases, glutathione S-transferases, and ATP-binding cassette transporters could be up- or down-regulated with exposure to sublethal concentrations of insecticides [ 44 , 45 ]. Transcriptomic analyses will therefore be carried out in S. litura treated with sublethal doses of broflanilide to identify related transcriptional changes, understand the functions of detoxifying genes, and finally delineate the mechanisms of action of this insecticide.…”