Fumarate mitigates disruption induced by fenpropathrin in the silkworm Bombyx mori (Lepidoptera): A metabolomics study

Glyphosate exposure affected longevity-related pathways and reduced survival in asian honey bees (Apis cerana)

Glyphosate (N-(phosphonomethyl)glycine, GLY) ranks among the most extensively used and effective herbicides globally. However, excessive GLY utilization poses a substantial threat to the survival of honey bees (Apis cerana). Here we monitored the survival status of A. cerana treated with GLY, and conducted transcriptome sequencing of the bee gut and head to further explore potential GLY influences at the molecular level. We observed that the mortality rate of bees increased as GLY concentration escalated. Pivotal pathways emerged in response to the GLY treatment, with a substantial number of differentially expressed genes enriched in the longevity regulating pathway - multiple species. This strongly suggested that GLY may influence the physiological behavior of bees by impacting this particular pathway. Moreover, our analysis revealed a notable reduction in the enzymatic activities of CYP450 and AChE in both the bee head and intestines of when exposed to GLY. Conversely, the enzymatic activity of superoxide dismutase (SOD) in the head remained unaffected, whereas in the intestines, it exhibited a significant increase. Additionally, prophenol oxidase (PPO) and glutathione-S-transferases (GSTs) displayed contrasting trends in enzymatic activity in both organs. This study offers valuable insights into how GLY impacted the survival of A. cerana.

Uric acid metabolism promotes apoptosis against Bombyx mori nucleopolyhedrovirus in silkworm, Bombyx mori

The white epidermis of silkworms is due to the accumulation of uric acid crystals. Abnormal silkworm uric acid metabolism decreases uric acid production, leading to a transparent or translucent phenotype. The oily silkworm op50 is a mutant strain with a highly transparent epidermis derived from the p50 strain. It shows more susceptibility to Bombyx mori nucleopolyhedrovirus (BmNPV) infection than the wild type; however, the underlying mechanism is unknown. This study analysed the changes in 34 metabolites in p50 and op50 at different times following BmNPV infection based on comparative metabolomics. The differential metabolites were mainly clustered in six metabolic pathways. Of these, the uric acid pathway was identified as critical for resistance in silkworms, as feeding with inosine significantly enhanced larval resistance compared to other metabolites and modulated other metabolic pathways. Additionally, the increased level of resistance to BmNPV in inosine-fed silkworms was associated with the regulation of apoptosis, which is mediated by the reactive oxygen species produced during uric acid synthesis. Furthermore, feeding the industrial strain Jingsong (JS) with inosine significantly increased the level of larval resistance to BmNPV, indicating its potential application in controlling the virus in sericulture. These results lay the foundation for clarifying the resistance mechanism of silkworms to BmNPV and provide new strategies and methods for the biological control of pests.

Natural Coumarin Shows Toxicity to Spodoptera litura by Inhibiting Detoxification Enzymes and Glycometabolism

Coumarin and its derivatives are plant-derived compounds that exhibit potent insecticidal properties. In this study, we found that natural coumarin significantly inhibited the growth and development of Spodoptera litura larvae through toxicological assay. By transcriptomic sequencing, 80 and 45 differentially expressed genes (DEGs) related to detoxification were identified from 0 to 24 h and 24 to 48 h in S. litura after coumarin treatment, respectively. Enzyme activity analysis showed that CYP450 and acetylcholinesterase (AChE) activities significantly decreased at 48 h after coumarin treatment, while glutathione S-transferases (GST) activity increased at 24 h. Silencing of SlCYP324A16 gene by RNA interference significantly increased S. litura larval mortality and decreased individual weight after treatment with coumarin. Additionally, the expression levels of DEGs involved in glycolysis and tricarboxylic acid (TCA) cycle were inhibited at 24 h after coumarin treatment, while their expression levels were upregulated at 48 h. Furthermore, metabonomics analysis identified 391 differential metabolites involved in purine metabolism, amino acid metabolism, and TCA cycle from 0 to 24 h after treated with coumarin and 352 differential metabolites associated with ATP-binding cassette (ABC) transporters and amino acid metabolism. These results provide an in-depth understanding of the toxicological mechanism of coumarin on S. litura.