Knockdown of CYP9A9 increases the susceptibility to lufenuron, methoxyfenozide and a mixture of both in Spodoptera exigua

Abstract

Lufenuron (LUF) and Methoxyfenozide (MET) as Insect Growth Regulators (IGRs) contribute to the current control of the catastrophic crop pest, Spodoptera exigua (Lepidoptera, Noctuidae). Yet S. exigua has evolved resistance to LUF and MET, which is possibly mediated by cytochrome P450 monooxygenases (P450s), particularly from the CYP3 clade family, as it plays a key role in the detoxification of insecticides. However, a mixture of LUF and MET (MML) (optimal ratio: 6:4) remains highly insecticidal. Here, we analysed the response of S. exigua to sublethal concentrations of LUF, MET, and MML via transcriptomics. Twelve differentially expressed genes (DEGs) encoding CYP3 clade members were observed in transcriptomes and CYP9A9 was significantly upregulated after treatment with LUF, MET, and MML. Further, CYP9A9 was most highly expressed in the midgut of L4 S. exigua larvae. RNAi-mediated knockdown of CYP9A9 reduced the activity of CYP450 and increased the susceptibility of S. exigua larvae to LUF, MET, and MML. Thus, CYP9A9 plays a key role in the detoxification of LUF, MET, and MML in S. exigua. These findings provide new insights into insecticidal actions of IGRs, which can be applied to the establishment of novel pest management strategies.

Lufenuron treatment temporarily represses gene expression and affects the SUMO pathway in liver of Atlantic salmon

“…Mammalian studies have shown similar results with increased expression of CYP3A protein after diflubenzuron exposure (Dubois et al, 1996;Sapone et al, 2005). In insects, biotransformation of lufenuron depends on CYP9 and CYP12 proteins (Bogwitz et al, 2005;Zhang et al, 2023), CYP families that belong to the mammalian CYP3 and CYP5 families.…”

“…Mammalian studies have shown similar results with increased expression of CYP3A protein after diflubenzuron exposure (Dubois et al., 1996; Sapone et al., 2005). In insects, biotransformation of lufenuron depends on CYP9 and CYP12 proteins (Bogwitz et al., 2005; Zhang et al., 2023), CYP families that belong to the mammalian CYP3 and CYP5 families. Although CYP3A appears to be involved in the detoxification of benzoylurea insecticides in vertebrates, this gene was not differentially regulated in this study ( cyp3a27 was 1.4‐fold upregulated at day 14 ( p ‐value = .03, p ‐adj = .22).…”

“…Insect studies suggest that the pesticide can be metabolized and detoxified by the cytochrome P450 system (do Nascimento et al., 2015; Hafeez et al., 2019). Recent studies suggest that CYP9A enzymes are involved in the detoxification of lufenuron in insects (Zhang et al., 2023). CYP9A enzymes belong to the CYP3 clan in mammalian species (Shi et al., 2021).…”

A Malpighian Tubule-Specific P450 Gene SlCYP9A75a Contributes to Xenobiotic Tolerance in Spodoptera litura

“…In addition to the diverse genetic options for insecticide resistance evolution caused by the amplification of P450s, the involvement of P450 gene overexpression in xenobiotic detoxification has been widely studied. , CYP6DP genes in Trialeurodes vaporariorum and Bemisia tabaci showed a strongly transcriptional response to nicotine, and several CYP6DP genes were found to be related to imidacloprid resistance . Inducible CYP9A9 of Spodoptera exigua was verified to participate in lufenuron and methoxyfenozide detoxification by using RNAi S.…”

A Comparative Study of Transcriptional Regulation Mechanism of Cytochrome P450 CYP6B7 between Resistant and Susceptible Strains of Helicoverpa armigera

“…Nowadays a large number of P450 genes have been reported to be related to insect resistance. For example, the overexpression of CYP6B7 , CYP6B6 , CYP6B2 , CYP337B3 , CYP332A1 , and CYP6AE11 was associated with pyrethroids resistance in H. armigera . − Overexpression of P450 genes was also related to the resistance of other insects, such as Plutella xylostella , Spodoptera exigua , Tribolium castaneum , and Aphis gossypii . Gene expression in insects is sophisticated and involves in the process of transcription, while transcription factors are able to intricately regulate the transcription of many functional genes that respond to external environmental stresses including insecticides .…”