Rahul Debnath, Justin George, Rupesh Kariyat, Nathan Little, Maribel Portilla, Gadi V. P. Reddy
BACKGROUND: Female insects exhibit oviposition preferences that maximize the survival and development of their progeny. Although kaolin-based particle films are reported as physical repellents against herbivory, a significant research gap exists in their impact on herbivore feeding behavior and modulation of physio-chemical dynamics in row crop systems. We investigated how foliar application of kaolin impacts soybean defenses against two generalist and highly destructive insect pests, soybean looper (SBL, Chrysodeixis includens) and southern green stink bug (SGSB, Nezara viridula). RESULTS: Our results show that gravid females exhibited significant avoidance (>70%) of kaolin and insecticide-treated plants during the oviposition choice assays. Evidence from behavioral choice assays using larvae/nymphs indicated that kaolin strongly enhances soybean defenses against herbivore attack. Significant reduction (>75%) in the survival of immature stages on kaolin plus insecticide treated plants indicated that kaolin adversely affects early insect development. Analyses of plant physiological and biochemical traits showed that kaolin particles not only facilitate as physical barriers but also improve plant physio-chemical resilience. Moreover, field applications further showed that insect pest abundance was significantly lower on kaolin treated plants, compared to untreated control plants, mimicking insecticidal effects. CONCLUSION: Together, these findings highlight kaolin's dual role as a physical barrier and as an ovipositional deterrent, reinforcing its potential as a sustainable, non-chemical strategy for integrated pest management aimed at restricting early pest establishment and mitigating overall pest pressure under field conditions. © 2026 Society of Chemical Industry. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.