RNA interference revealed the roles of two carboxylesterase genes in insecticide detoxification in Locusta migratoria

Abstract

Carboxylesterases (CarEs) play key roles in metabolism of specific hormones and detoxification of dietary and environmental xenobiotics in insects. We sequenced and characterized CarE cDNAs putatively derived from two different genes named LmCesA1 and LmCesA2 from the migratory locust, Locusta migratoria, one of the most important agricultural pests in the world. The full-length cDNAs of LmCesA1 (1892 bp) and LmCesA2 (1643 bp) encode 543 and 501 amino acid residues, respectively. The two deduced CarEs share a characteristic α/β-hydrolase structure, including a catalytic triad composed of Ser-Glu (Asp)-His and a consensus sequence GQSAG, which suggests that both CarEs are biologically active. Phylogenetic analysis grouped both LmCesA1 and LmCesA2 into clade A which has been suggested to be involved in dietary detoxification. Both transcripts were highly expressed in all the nymphal and adult stages, but only slightly expressed in eggs. Analyses of tissue-dependent expression and in situ hybridization revealed that both transcripts were primarily expressed in gastric caeca. RNA interference (RNAi) of LmCesA1 and LmCesA2 followed by a topical application of carbaryl or deltamethrin did not lead to a significantly increased mortality with either insecticide. However, RNAi of LmCesA1 and LmCesA2 increased insect mortalities by 20.9 and 14.5%, respectively, when chlorpyrifos was applied.These results suggest that these genes might not play a significantly role in detoxification of carbaryl and deltamethrin but are most likely to be involved in detoxification of chlorpyrifos in L. migratoria.3

RNA interference: Applications and advances in insect toxicology and insect pest management

“…After the expression of CYP6BQ9 was suppressed by RNAi, the resistance level was significantly reduced [59]. The role of the T. castaneum CYP6BQ9 in deltamethrin resistance was further confirmed through transgenic expression in Drosophila melanogaster, and with kinetic studies of its enzyme heterologously expressed in a baculovirus expression system [44].…”

“…These results demonstrate that the overexpression of CarE plays an important role in OP resistance in this aphid species. Additionally, dsRNA targeting CarE1 and CarE2 led to the increased mortality in Locusta migratoria (20.9 and 14.5%, respectively) when chlorpyrifos was applied to this insect [44]. Furthermore, L. migratoria nymphs injected with CarE9 and CarE25 dsRNAs followed by malathion exposures increased the mortality from 34 to 65% and 54%, respectively [50].…”

Insecticidal Activity of Melaleuca alternifolia Essential Oil and RNA-Seq Analysis of Sitophilus zeamais Transcriptome in Response to Oil Fumigation

“…To cope with xenobiotic compounds, the insects can utilize a variety of detoxifying enzymes, including glutathione S-transferase (GST) and carboxylesterase (CarE) [15–18]. Or, the insects can decrease the sensitivity of the target site of pesticides, for example, the nerve conduction enzyme acetylcholinesterase (AChE) [16].…”

Transcriptome mining: Multigene panel to test delousing drug response in the sea louse Caligus rogercresseyi

“…The expression of Carboxylesterase was blocked in Locusta migratoria through RNAi, and an increased susceptibility of L. migratoria to an organophosphate was observed. However, a similar effect was not observed when L. migratoria was treated with pyrethroids (Zhang et al, 2013). In strains of L. salmonis resistant to EMB, increased expression levels of Carboxylesterase were observed as compared to susceptible strains (Carmichael et al, 2013).…”

“…The RNA-seq analysis performed in this study showed that genes with protease functions, such as trypsin and metalloproteinase, were highly expressed in both males and females. Another esterase that participates in processes of detoxifying xenobiotics in insects is Carboxylesterase, which is principally related to generating resistance to organophosphates (Hemingway et al, 2004;Zhang et al, 2013). The expression of Carboxylesterase was blocked in Locusta migratoria through RNAi, and an increased susceptibility of L. migratoria to an organophosphate was observed.…”