Trehalase regulates energy metabolism in insects by converting trehalose into two glucose molecules. High amounts of trehalase are critical for insect flight and larval stress resistance. However, whether trehalase participates in the development of pesticide resistance remains unclear. In this study, we explored this phenomenon and the mechanism that underlies the regulation of Trehalase transcription. We found that overexpression of PxTreh1 and PxTreh2 induced Bacillus thuringiensis (Bt) resistance in Plutella xylostella. The promoter sequences of PxTreh1 and PxTreh2 were also cloned and identified. The dual-luciferase reporter system and RNA interference technology revealed that the expression of PxTreh1 and PxTreh2 genes is possibly regulated by the CCAAT enhancer-binding protein (C/EBPα). A yeast one-hybrid experiment confirmed the interaction between C/EBPα and the PxTreh2 promoter. The findings of this study suggest that C/EBPα mediates the adaptability of P. xylostella to adverse environmental stressors by regulating the expression of trehalase.

The diamondback moth (Plutella xylostella) is one of the most destructive lepidopteran pests of cruciferous vegetables, and insights into regulation of its physiological processes contribute towards the development of new pesticides against it. Thus, we investigated the regulatory functions of its β-adrenergic-like octopamine receptor (PxOctβ3). The open reading frame (ORF) of PxOctβ3 was phylogenetically analyzed, and the levels of expression of the receptor mRNA were determined. This ORF was also cloned and expressed in HEK-293 cells. A series of octopamine receptor agonists and antagonists were tested against PxOctβ3. We showed that the receptor is a member of the Octβ3 protein family, and an analysis using quantitative PCR showed that it was expressed at all developmental stages of P. xylostella. Octopamine activated PxOctβ3, resulting in increased levels of intracellular cAMP. Furthermore, the agonists naphazoline, clonidine, 2-phenethylamine, and amitraz activated the PxOctβ3 receptor, and naphazoline was the most effective. Only metoclopramide and mianserin had significant antagonistic effects on PxOctβ3, whereas yohimbine, phentolamine, and chlorpromazine lacked obvious antagonistic effects. The injection of double-stranded RNA in an RNA interference assay indicated that PxOctβ3 regulates development in P. xylostella. This study demonstrated the pharmacological properties and functions of PxOctβ3 in P. xylostella, thus, providing a theoretical basis for the design of pesticides that target octopamine receptors.