Functional role of <i>TaGSTs1</i> in the detoxification of spinetoram and development of <i>Tuta absoluta</i>

<i>Tuta absoluta</i> has evolved resistance to many biological insecticides, resulting in significant annual agricultural and economic losses. Glutathione <i>S</i>-transferases (GSTs) are one of the major insect detoxification enzyme systems. However, the detoxification metabolism of GSTs in <i>T. absoluta</i> against biological insecticides remains poorly understood. In this study, We identified five key <i>GST</i> genes (<i>TaGSTs1, TaGSTs2, TaGSTe1, TaGSTe3</i>, and <i>TaGSTd1</i>) by screening from the comparative transcriptomes of two regional populations of <i>T. absoluta</i> in Xinjiang, China. Among the five GSTs, <i>TaGSTs1</i> exhibited a significantly high expression level during the larval stage of <i>T. absoluta</i> following exposure to the LC₅₀ dose of spinetoram. This gene was subsequently cloned, and its expression was knocked down using RNA interference to further analyse its role in the detoxification of spinetoram, as well as in the growth and development of <i>T. absoluta</i>. The results showed that <i>TaGSTs1</i> contains a typical <i>GST</i> gene domain and was highly conserved within the Lepidoptera clade. Silencing of the <i>TaGSTs1</i> gene led to a significant increase in the susceptibility of <i>T. absoluta</i> to spinetoram, as evidenced by an extension in the duration of leaf-mining and in the development time from the 2^nd to the 4^th instar larval stage, which were 35.7% and 19.6% longer, respectively, than those of ddH₂O and ds<i>GFP</i> controls. Furthermore, the mortality rate of larvae treated with ds<i>TaGSTs1</i> reached 57.3% by the 7th day. These findings indicate that <i>TaGSTs1</i> plays a crucial role in the detoxification of spinetoram and in the growth and development of <i>T. absoluta</i> larvae.