Genlin Mao

Exocarpium Citri Grandis (ECG, Huajuhong) is a traditional medicinal and edible citrus product whose characteristic quality develops during fixation and drying, but the underlying metabolic basis remains unclear. Here, widely targeted metabolomics, amino acid profiling, volatile analysis, and enzyme activity assays were integrated to characterize dynamic chemical changes during traditional ECG processing. Volatile analysis revealed a gradual aroma shift from fresh citrus–woody–spicy notes to a more complex citrus–floral–herbal profile, associated with decreased sesquiterpenes and monoterpene hydrocarbons and increased oxygenated terpenoids, esters, and aldehydes. Among 1,928 annotated metabolites, flavonoids, saccharides, phenolic acids, coumarins, and amino acids changed markedly during processing. Overall, fixation mainly served as an enzyme-inactivation stage accompanied by early metabolic remodeling, whereas drying was the key stage driving quality formation and extensive metabolite transformation. These findings indicate that ECG processing is a dynamic biochemical and chemical transformation process rather than simple dehydration.

This study aimed to investigate the inhibitory effect of toosendanin (TSN) on the growth and development of Spodoptera litura (Fabricius, 1775), especially in terms of feeding preference, larval growth and development, nutritional indices, and enzyme activities. The feeding preference of S. litura, larval growth and development, and nutritional indices were evaluated using the diet incorporation method. The activities of three detoxification, three digestive, and three antioxidant enzymes were determined using spectrophotometric, micro-assay, and microplate methods. The feeding preference of S. litura exposed to TSN indicated that the larvae had a significant preference for the untreated (control) feed compared with the TSN-supplemented feed. The growth and development results showed a prolongation of the larval developmental period by approximately one instar in S. litura larvae fed TSN-supplemented feed. At the highest concentration (100 μg/g), larval weight was 0.76 times that of the control group, with a 27.34% reduction in the pupation rate and a 23.58% reduction in the emergence rate. All differences were statistically significant compared with the control group. In addition, the pupal and adult deformity rates were significantly higher than those in the control group, being 14.68 and 5.67 times higher, respectively, at this concentration. Growth inhibition increased with increasing TSN concentration. In terms of nutritional efficiency, TSN treatment reduced food intake and decreased food conversion rate, thereby inhibiting the relative growth rate of the 4th instar larvae. Further, TSN treatment significantly increased the activities of trypsin, α-amylase, glutathione S-transferase, carboxylesterase, superoxide dismutase, peroxidase, and catalase, and had no significant effect on lipase activity, and significantly reduced cytochrome P450 enzyme activity. TSN can significantly inhibit the digestion and absorption of nutrients in S. litura larvae, slow down their growth and development, and increase the pupal and adult deformity rates, thereby protecting plants against infestation by S. litura.

BACKGROUND: Spodoptera litura is one of the most harmful lepidoptera pests in China, and is difficult to control due to its strong resistance to the current frequently used insecticide species. The requirement to develop pesticides with novel toxicology mechanisms to control S. litura is urgent. The quassinoid of bruceine D display outstanding systemic properties and strong insecticidal activity against S. litura, which possess notable application potential for integrative management of S. litura, but the mechanism of toxicity remains unclear.RESULTS: In this study, we found that bruceine D exerts potent growth inhibitory activity against S. litura, disrupting the ecdysone and juvenile hormone titers, and causing long‐term adverse effects. Association analysis between transcriptomics and metabolomics suggested that bruceine D affected the digestion and absorption capacity of S. litura larvae by inducing a strong oxidative stress response and cell apoptosis in the intestine. Further analysis demonstrated that bruceine D can inhibit the activities of digestive and antioxidant enzymes and induce malondialdehyde (MDA) and reactive oxygen species (ROS) overaccumulation in the midgut. Moreover, the protein level of Bax, cleavage caspase 3, and cytochrome c expressed in cytoplasm (cyto) were up‐regulated by bruceine D, while Bcl‐2 and cytochrome c expressed in mitochondria (mito) were down‐regulated. In addition, there was a noticeable increase in caspase‐3 protease activity. Histopathological observations revealed that bruceine D damages the structure of midgut epithelial cells and activates lysosomes, which subsequently disrupts the midgut tissue.CONCLUSION: Overall, our findings suggested that bruceine D induced excessive ROS accumulation in midgut epithelial cells. The resulting cell apoptosis disrupted midgut tissue, leading ultimately to reduced nutrient digestion and absorption in the midgut and the inhibition of larval growth. © 2024 Society of Chemical Industry.

The oriental fruit fly Bactrocera dorsalis (Hendel) is a destructive polyphagous species that targets many economically important fruits and vegetables. The primary control of B. dorsalis relies mainly on the use of synthetic chemicals, and excessive use of these chemicals has adverse effects on both the environment and human health. Environmentally friendly management of pests involving plant essential oils is useful for controlling the populations of pests responsible for decreasing the yields and quality of crops. In the present study, we demonstrate that clove bud essential oil (CBEO) is strongly attractive to sexually mature males. Mature males responded to the CBEO differently throughout the day; the strongest response was elicited during the day and decreased at dusk. Virgin and mated mature males did not respond differently to CBEO. No obvious response behaviour to the CBEO was observed in two species of beneficial natural predator ladybirds. In addition, a cytotoxicity assessment demonstrated that CBEO is nontoxic to normal human and mouse cells. Based on our laboratory experiments, CBEO may serve as a promising, sustainable, and environmentally friendly attractant for B. dorsalis males; however, field experiments are needed to confirm this hypothesis.

The ability to visualize the movement of glycosyl insecticides contributes to learning their translocation and distribution in plants. In our present work, a novel fluorescent glucose–fipronil conjugate N-[3-cyano-1-[2,6-dichloro-4-(trifluoromethyl)phenyl]-4-[(trifluoromethyl)sulfinyl]-1H-pyrazol-5-yl]-1-(2-[N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino]-2-deoxy-β-d-glucopyranosyl)-1H-1,2,3-triazole-4-methanamine (2-NBDGTF), was obtained via click chemistry. Disk uptake experiments showed that an active carrier-mediated system was involved in the 2-NBDGTF uptake process. Meanwhile, 2-NBDGTF exhibited comparable phloem mobility with GTF in castor bean seedlings. Visualization of 2-NBDGTF uptake and transport experiment showed that this fluorescent glucose–fipronil conjugate could be loaded into sieve tubes after transiting through epidermal cells and mesophyll cells and then translocate from cotyledon to hypocotyl via phloem in castor bean seedlings. The results above determined that it is a promising fluorescence tagging approach for revealing the activities of glycosyl insecticides and 2-NBDGTF is a reasonable and feasible fluorescent surrogate of GTF for tracing the distribution of glucose–fipronil conjugates.