Plant volatile TMTT suppresses reproduction of the brown planthopper by affecting the neuropeptide receptor CapaR

BACKGROUND: The brown planthopper, Nilaparvata lugens, is a major rice pest whose management heavily depends on chemical insecticides, raising concerns over resistance and ecological safety. Herbivore-induced plant volatiles (HIPVs) are key components of plant defense and can influence insect behavior and physiology. However, their molecular effects on insect reproduction remain poorly understood. This study aimed to investigate how the plant volatile (3E,7E)-4,8,12-trimethyltrideca-1,3,7,11-tetraene (TMTT) affects the reproduction of N. lugens and to elucidate the underlying molecular mechanisms. RESULTS: Exposure to TMTT significantly reduced oviposition under laboratory conditions and in semi-field cages, and delayed ovarian development without affecting survival. Transcriptomic profiling showed that the neuropeptide receptor gene CapaR was the most strongly upregulated in the ovary (18.5-fold at day 1; 10.8-fold at day 5). Functional assays demonstrated that RNA interference-mediated silencing of CapaR reversed TMTT's effects, leading to increased egg production, a shortened preoviposition period and accelerating ovarian maturation. These results indicate that CapaR is involved in the inhibitory effect of TMTT on reproduction. CONCLUSION: This study identifies CapaR as a molecular link between plant volatile perception and insect reproductive regulation. The findings reveal a novel neuropeptide-based mechanism by which HIPVs modulate insect fecundity and highlight the potential of environmentally friendly, fecundity-targeted pest management strategies for rice pests. © 2026 Society of Chemical Industry.