BACKGROUND: The increasing challenges of pesticide resistance and environmental degradation in modern agriculture require sustainable pest management strategies. This study investigates the efficacy of a specific type of hetero-chitooligosaccharide called partially deacetylated chitooligosaccharide enriched in d-glucosamine (DACOS; 85.6% deacetylation, an average molecular mass of 1092.52 Da), as a plant defense elicitor against the two-spotted spider mite, Tetranychus urticae Koch. RESULTS: (ppm), which reduced mite survival by 30% and cumulative fecundity by 41% after 6 days. Systemic effects were strongest at 160 ppm, indicating distinct concentration requirements for local versus systemic defense induction. Behavioral choice assays revealed that DACOS-treated leaves induced 73% mite repellency. No direct acaricidal effects were observed, which confirms the role of DACOS as a plant defense elicitor. Metabolic profiling revealed enriched pathways (e.g., monoterpenoid biosynthesis and α-linolenic acid metabolism) that produce volatile organic compounds with repellent properties. CONCLUSION: These findings suggest that DACOS is an environmentally friendly and non-biotic induced resistance stimulus that can enhance plant defense, bypass pesticide resistance, and promote the sustainability of crop production. © 2026 Society of Chemical Industry.
Jiang et al. (Mon,) studied this question.