Odors from nymphal exuviae attract nymphs and gravid females of the cotton seed bug, Oxycarenus hyalinipennis (Hemiptera: Oxycarenidae)

The cotton seed bug (CSB), Oxycarenus hyalinipennis (Hemiptera: Oxycarenidae), globally emerging pest native to Africa, is a serious insect pest of cotton, posing a significant threat to crop yield and quality. Both nymphs and adults feed on developing cotton seeds. Volatile organic compounds (VOCs) are key mediators of behavioral responses in heteropteran insects, including CSB, influencing aggregation, mating, and oviposition. In this study, we evaluated the behavioral role of volatiles emitted from nymph exuviae of CSB. Using a combination of Y-tube olfactometer, dual-choice refuge, and dual-choice oviposition bioassays, we assessed the responses of different developmental stages and reproductive statuses to exuviae-associated VOCs. Our results showed that nymphs and mated females were significantly attracted to nymph exuviae VOCs, with nymphs showing >78% and mated females >73% preference in both the Y-tube and refuge assays, whereas unmated females and males (mated and unmated) exhibited no attraction or a slight aversion. Furthermore, gravid females preferentially oviposited on cotton seeds exposed to nymph exuviae VOCs, suggesting that these chemical cues signal suitable oviposition sites, optimizing the chances for the offspring survivorship. This study provides the first evidence that exuviae-associated VOCs in O. hyalinipennis serve as multifunctional semiochemicals, guiding both aggregation and reproductive behavior. These findings offer new insights into the chemical ecology of CSB and highlight potential avenues for semiochemical-based pest management strategies to control CSB population, including the development of attract-and-kill systems for use in integrated pest management (IPM) programs. • Cotton seed bug (CSB) nymphs and gravid females consistently showed significant attraction to nymph exuviae-associated volatile organic compounds (VOCs). • Males (both mated and unmated) and unmated females exhibited either avoidance or indifference to nymph exuviae VOCs. • This is the first study to demonstrate that gravid CSB females use nymph exuviae-associated VOCs as oviposition cues. • Nymph exuviae-associated VOCs serve dual ecological roles—promoting aggregation and guiding oviposition site selection.