Validamycin treatment significantly inhibits the glycometabolism and chitin synthesis in the common cutworm,Spodoptera litura

Validamycin,as a broadly applied antibiotic,has been used to control rice sheath blight disease.Furthermore,validamycin was considered as an insecticide to control agricultural pests.Insight into the mechanism of validamycin’s action on insects can provide molecular targets for the control of agricultural pests.In this study,a toxicological test analysis revealed that Spodoptera litura larval growth and development was significantly inhibited and the pupation rate was significantly reduced with the increase of the concentration of validamycin.According to the NMR-based metabolomic analysis,a total of 15 metabolites involved in glycolysis and tricarboxylic acid cycle(TCA)pathways were identified.Additionally,trehalase activities,glucose and chitin contents were significantly downregulated,but the trehalose content was upregulated after exposure to validamycin.Reverse transcription quantitative PCR analysis revealed that the expression level of genes involved in glycolysis,TCA and chitin synthesis were upregulated after treating with validamycin.Further chitin staining also confirmed that chitin content was downregulated at 12 h after validamycin treatment.Our results indicated that validamycin worked via two different molecular mechanisms,one through inhibiting glycometabolism and the other by inhibiting chitin synthesis in S.litura.The information lays a theoretical foundation for further control of S.litura.

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

The silkworm Bombyx mori L.is a model organism of the order Lepidoptera.Understanding the mechanism of pesticide resistance in silkworms is valuable for Lepidopteran pest control.In this study,comparative metabolomics was used to analyze the metabolites of 2 silkworm strains with different pesticide resistance levels at 6,12,and 24 h after feeding with fenpropathrin.Twenty-six of 27 metabolites showed significant differences after fenpropathrin treatment and were classified into 6 metabolic pathways:glycerophospholipid metabolism,sulfur metabolism,glycolysis,amino acid metabolism,the urea cycle,and the tricarboxylic acid(TCA)cycle.After analyzing the percentage changes in the metabolic pathways at the 3 time points,sulfur metabolism,glycolysis,and the TCA cycle showed significant responses to fenpropathrin.Confirmatory experiments were performed by feeding silkworms with key metabolites of the 3 pathways.The combination of iron(II)fumarate+folic acid(IF-FA)enhanced fenpropathrin resistance in silkworms 6.38 fold,indicating that the TCA cycle is the core pathway associated with resistance.Furthermore,the disruption of several energy-related metabolic pathways caused by fenpropathrin was shown to be recovered by IF-FA in vitro.Therefore,IF-FA may have a role in boosting silkworm pesticide resistance by modulating the equilibrium between the TCA cycle and its related metabolic pathways.