In the context of climate change, characterized by an increase in average precipitation, agricultural pests have demonstrated enhanced adaptability to high humidity and other challenging environmental conditions, thereby intensifying the need for effective prevention and control measures. Among these pests, Megoura crassicauda (Hemiptera: Aphididae) represents a significant threat to both crop yield and quality. The aim of this study was to investigate the physiological behavioral changes and the regulatory mechanisms of trehalose metabolism in M. crassicauda under conditions of high-humidity stress. Additionally, we sought to explore the survival strategies and water regulation mechanisms employed by this insect, with the goal of identifying new biological targets for its management. The findings indicated that, despite an increase in environmental humidity, there was no significant difference in the survival rate of M. crassicauda. However, a reduction in developmental duration and reproductive capacity was observed. Increased humidity correlated with elevated trehalose levels and decreased glycogen content. Notably, although the relative expression levels of trehalase (TRE) and Trehalose-6-phosphate synthase (TPS) were downregulated, Trehalose-6-phosphate phosphatase (TPP) expression was upregulated. These results suggest that high humidity environments significantly influence the growth, development, and trehalose metabolism of M. crassicauda. It appears that adaptations to high-humidity conditions in M. crassicauda are facilitated by modulations in the types and distribution of sugars within their bodies, achieved through alterations in the expression of genes associated with trehalose metabolism. In summary, the results of this study indicate that high humidity significantly affects the development and sugar metabolism of M. crassicauda. These changes may represent one of the potential mechanisms underlying its environmental adaptation and migration. This insight provides valuable assistance for predicting the occurrence and migration of the pest M. crassicauda.
