Identification and validation of ABCB transporter genes involved in chlorantraniliprole and emamectin benzoate tolerance in Spodoptera exigua.

Spodoptera exigua is a significant invasive pest that has developed resistance to various commonly applied insecticides. The detoxification of insecticides in insects may partially depend on ATP-binding cassette (ABC) transporters. Although the functions of ABCB subfamily genes are diverse in insects, the specific roles of ABCBs in S. exigua remain largely unexplored. This research focused on identifying ten SeABCB genes and characterizing their expression profiles across various developmental stages and tissues, as well as in response to different insecticide treatments. Our findings indicate that SeABCB genes are expressed at all developmental stages, with most ABC transporters exhibiting higher expression levels during the pupal and adult stages compared to the larval stage. Furthermore, high expression levels of SeABCBs were observed in diverse tissues: SeABCB1 and SeABCB6 were found to be more abundant in the midgut, while SeABCB3 and SeABCB4 exhibited significantly higher expression in fat bodies. The expression of SeABCB2, SeABCB5 and SeABCB8 was notable in Malpighian tubules, and SeABCB9 showed a higher expression level in the cuticle than in other tissues. Eight ABCBs were upregulated in S. exigua following exposure to chlorantraniliprole and emamectin benzoate. Gene functional analysis based on RNAi proved that SeABCB4 and SeABCB9 are involved in the tolerance of S. exigua to chlorantraniliprole, while SeABCB1 and SeABCB9 participate in the transport or metabolism of emamectin benzoate in S. exigua. In summary, our research provides significant insights into the role of SeABCBs in the detoxification mechanisms of S. exigua.