BACKGROUND
Chlorantraniliprole (CAP) is an efficient anthranilic diamide insecticide against economically important pests, such as the oriental armyworm, Mythimna separata (Lepidoptera: Noctuidae). Resistance to CAP may develop due to enhanced enzymatic detoxification. The Glutathione S-transferase (GST) superfamily in M. separata hasn't been systematically characterized. The aim of this study was therefore to explore the effects of lethal and sublethal doses of CAP on M. separata larvae, screen differentially expressed genes (DEGs) responding to CAP exposure, identify and characterize the GST superfamily, and analyze the metabolism of CAP by recombinant GSTs.
RESULTS
The toxicity bioassay showed that CAP was active against M. separata third instar larvae. LC50 was 17.615, 3.127, and 1.336 mg/L after 24, 48, and 72 hr, respectively. Poisoned larvae showed contracted somites and disrupted midgut. Total GST activity in larvae significantly elevated 24 hr after CAP exposure. RNA-seq generated 43,055 unigenes with an average length of 1,010 bp. 567 upregulated and 692 downregulated DEGs responding to CAP treatment were screened. 35 GST genes were identified from unigenes, including 31 cytosolic, 3 microsomal, and 1 unclassified. The expression profile of GST genes was analyzed using samples from different developmental stages, adult tissues, and CAP treatments. Metabolic assays indicated that CAP was depleted by recombinant MseGSTe2 and MseGSTs6.
CONCLUSIONS
This study provides insight into the toxicological and transcriptomic effects in M. separata larvae exposed to CAP. The identification and functional characterization of the GST superfamily will improve our understanding of CAP detoxification by GSTs. This article is protected by copyright. All rights reserved.