Heavy metal pollution is a serious global environmental issue. It threatens human and ecological health. Heavy metals can accumulate in the soil over extended periods and inevitably transfer through the food chain to herbivorous insects and their natural enemies, leading to various adverse effects. This study aimed to investigate the stress responses and biochemical metabolic changes of aphids and one of aphids’ predators, ladybugs, under cadmium (Cd) and lead (Pb) stress by constructing a food chain of Vicia faba L., Megoura crassicauda, and Harmonia axyridis. The results showed that aphids and ladybugs had a notable accumulation of Cd²⁺ and Pb²⁺. Insects can adapt to heavy metal stress by regulating their energy metabolism pathways. Glycogen content in the first filial generation (F1) aphids decreased significantly, glucose content in the second filial generation (F2) to the fourth filial generation (F4) adult aphids significantly increased, and trehalose content in the F1 adult aphids increased significantly. Moreover, the relative expression levels of trehalase (TRE) and trehalose-6-phosphate synthase (TPS) in the F1 adult aphids were significantly higher than those in the control group, and the expression levels of TPS genes in the second filial generation to the fifth filial generation (F2 to F5) aphids decreased, suggesting that insects can resist heavy metal stress by regulating trehalose metabolism. The fertility of female aphids in all treatment groups was reduced compared to the control group. Additionally, the relative expression level of vitellogenin (Vg) was down-regulated in all aphid generations except the F1 aphids. There was interaction between heavy metal concentration and aphid generation, and it significantly affected the number of aphids’ offspring and the expression of the aphid Vg gene. The developmental duration of the ladybugs from the second to fourth instars was prolonged, and the weight decreased significantly from the prepupa to the adult stages. These results contribute to understanding the effects of Cd²⁺–Pb²⁺ accumulation on phytophagous insects and higher trophic levels’ natural enemies, laying the foundation for protecting natural enemies and maintaining ecosystem stability.

The fecundity of Nilaparvata lugens (brown planthopper) is influenced by trehalase (TRE). To investigate the mechanism by which trehalose affects the reproduction of N. lugens, we conducted a comparative transcriptomic and metabolomic analysis of the ovaries of N. lugens following injection with dsTREs and validamycin (a TRE inhibitor). The results revealed that 844 differentially expressed genes (DEGs) were identified between the dsGFP and dsTREs injection groups, with 317 up-regulated genes and 527 down-regulated genes. Additionally, 1451 DEGs were identified between the water and validamycin injection groups, with 637 up-regulated genes and 814 down-regulated genes. The total number of DEGs identified between the two comparison groups was 236. The overlapping DEGs were implicated in various biological processes, including protein metabolism, fatty acid metabolism, AMPK signaling, mTOR signaling, insulin/insulin-like growth factor signaling (IIS), the tricarboxylic acid (TCA) cycle, oxidative phosphorylation, and the cellular process of meiosis in oocytes. These results suggest that the inhibition of TRE expression may lead to alterations in ovarian nutrient and energy metabolism by modulating glucose transport and affecting amino acid metabolic pathways. These alterations may influence the reproduction of N. lugens by modulating reproductive regulatory signals. These findings provide robust evidence supporting the mechanism through which trehalase inhibition reduces the reproductive capacity of N. lugens.

The beet webworm Loxostege sticticalis has caused significant economic losses to the production of agriculture and animal husbandry in China. Preference testing of larva feeding and adult oviposition and flight capability tests were carried out on five host plants: soybean, pigweed, pea, broad bean, and alfalfa. An experimental population life table and population growth trends over the subsequent 200 days were constructed. The test results show that the larvae showed no significant preference among different plants. However, adults lay more eggs on soybeans. The pests failed to complete a generation when fed on broad beans and alfalfas. When fed on pigweed, they showed the shortest larvae development period, the heaviest pupal weight, the longest adult longevity, and the largest egg-laying amount. The net reproductive rate (R₀), intrinsic rate of increase (r), finite rate of increase (λ), and simulated population growth trend of the pests fed on pigweed show the highest values, and those fed on peas showed the lowest values. The total flight distance and flight time of adults fed on pigweed and soybeans were significantly greater compared to those fed on peas. In summary, beet webworms fed on pigweed showed the fastest development and reproduction, the largest population, and the strongest flight capability.

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.