Phosphoglucomutase (PGM) is a key enzyme in glycolysis and gluconeogenesis, regulating both glycogen and trehalose metabolism in insects. In this study, we explored the potential function of phosphoglucomutase (PGM) using RNA interference technology in Nilaparvata lugens, the brown planthopper. PGM1 and PGM2 were found highly expressed in the midgut of brown planthoppers, with different expression levels in different instar nymphs. The glycogen, glucose, and trehalose levels were also significantly increased after brown planthoppers were injected with dsRNA targeting PGM1 (dsPGM1) or PGM2 (dsPGM2). In addition, injection of dsPGM1 or dsPGM2 resulted in increased membrane-bound trehalase activity but not soluble trehalase activity. Furthermore, the expression of genes related to trehalose and glycogen metabolism decreased significantly after injection with dsPGM1 and dsPGM2. The expression levels of genes involved in chitin metabolism in the brown planthopper were also significantly decreased and the insects showed wing deformities and difficulty molting following RNAi. We suggest that silencing of PGM1 and PGM2 expression directly inhibits trehalose metabolism, leading to impaired chitin synthesis.

High carbon dioxide concentrations can effectively control most storage pests. To estimate the toxicity effect of high concentrations of CO₂, four different concentrations of CO₂ (25% CO₂, 50% CO₂, 75% CO₂, and 95% CO₂) were used to treat Tribolium castaneum, and the biochemical (carbohydrate content and gene expression level) and physiological (mortality, pupation, eclosion rate, and weight) features of insects submitted to different treatments with CO₂ were evaluated. The T. castaneum mortality rate was 50% in approximately 2 days when exposed to a treatment with 95% CO₂. When the CO₂ concentration exceeded 75%, the pupation rate and eclosion rate of T. castaneum seriously declined. Higher than 25% CO₂ concentrations resulted in a lower weight and shrunken body size of T. castaneum. It was further found that different CO₂ concentration treatments all influenced the levels of the three carbohydrate contents in T. castaneum. In addition, according to the detection of trehalose metabolism pathway-related genes, T. castaneum mainly responds to stress factors via high expression of TPS, TRE1-2, and TRE1-3. Our results enrich the evaluation of the toxicity effect of CO₂ treatment on grain storage pests, providing a basis for further improving the method of regulating grain storage to control insect pests.