Trehalase is the only enzyme known for the irreversible splitting of trehalose and plays a major role in insect growth and development. In this report, we describe a basic study of the trehalase gene fragment encoding a soluble trehalase from Lissorhoptrus oryzophilus (LoTRE1). Sequence alignment and phylogenetic analysis suggested that LoTRE1 was similar to some known insect trehalases and belongs to the Coleoptera trehalase group. Additionally, LoTRE1 was expressed mainly in the fat body. Purified protein was obtained using heterologous expression of LoTRE1 in Escherichia coli, and the recombinant protein exhibited the ability to decompose trehalose. Enzyme–substrate docking indicated the potential involvement of other residues in the catalytic activity, in addition to Asp 333. Moreover, feeding of adults on LoTRE1 dsRNA silenced the transcription of LoTRE1 and thereby reduced the activity of trehalase and increased the trehalose content; it also led to a 12% death rate. This study reveals essential molecular features of trehalase and offers insights into the structural aspects of this enzyme, which might be related to its function. Taken together, the findings demonstrate that LoTRE1 is indispensable for adults of this pest and provide a new target for the control of L. oryzophilus.

The farming of insects has emerged as a novel source of proteins and lipids. The larvae of Allomyrina dichotoma, an important source insect, contain large concentrations of lipids; however, the constituents of these lipids are unknown. We used lipidomics and transcriptomics to analyze the deposition of glycerophospholipids in A. dichotoma larvae at different instars. A total of eight subclasses of 833 glycerophospholipid molecules were identified in A. dichotoma larvae. The results showed the lipid with the highest levels in A. dichotoma larvae was phosphatidylethanolamine (PE) followed by phosphatidylcholine (PC), and phosphatidylglycerol (PG). Glycerophospholipids in A. dichotoma larvae at three instars were clearly differentiated. Large amounts of PE and PC were deposited in Stage 3 larvae, and cardiolipin (CL), phosphatidylinositol (PI), phosphatidylserine (PS), and phosphatidic acids (PAs) showed a similar pattern. However, PG and phosphatidylinositol diphosphate (PIP) decreased in Stage 3 larvae. Furthermore, the metabolic pathways and the key genes related to glycerophospholipid synthesis were identified based on transcriptomes for A. dichotoma larvae. These results revealed the composition of glycerophospholipids. We also explored the molecular mechanism for deposition of glycerophospholipids during the developmental stages of A. dichotoma larvae. Our results provide insights for using A. dichotoma larvae to produce lipids.