Spodoptera exigua is a worldwide pest afflicting edible vegetables and has developed varying levels of resistance to insecticides. Methoxyfenozide (MET), an ecdysteroid agonist, is effective against lepidopteran pests such as
S. exigua. However, the mechanism of MET to
S. exigua remains unclear.
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Spodoptera exigua is a worldwide pest afflicting edible vegetables and has developed varying levels of resistance to insecticides. Methoxyfenozide (MET), an ecdysteroid agonist, is effective against lepidopteran pests such as
S. exigua. However, the mechanism of MET to
S. exigua remains unclear. In this study, we analyzed the expression patterns of genes related to the ecdysone signaling pathway in transcriptome data treated with sublethal doses of MET and analyzed how expression levels of key genes affect the toxicity of MET on
S. exigua. Our results demonstrated that 2639 genes were up-regulated and 2512 genes were down-regulated in
S. exigua treated with LC
30 of MET. Of these, 15 genes were involved in the ecdysone signaling pathway. qPCR results demonstrated that
ecdysone receptor A (
EcRA) expression levels significantly increased in
S. exigua when treated with different doses of MET, and that the RNAi-mediated silencing of
EcRA significantly increased mortality to 55.43% at 72 h when L3
S. exigua larvae were exposed to MET at the LC
30 dose. Additionally, knocking down
EcRA suppressed the most genes expressed in the ecdysone signaling pathway. The combination of MET and ds
EcRA affected the expression of
E74 and enhanced the expression of
TREA. These results demonstrate that the adverse effects of sublethal MET disturb the ecdysone signaling pathway in
S. exigua, and
EcRA is closely related to MET toxic effect. This study increases our collective understanding of the mechanisms of MET in insect pests.
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