Juvenile-associated odors attract immature nymphs and gravid female cotton seed bugs, Oxycarenus hyalinipennis

The cotton seed bug (CSB), Oxycarenus hyalinipennis, is a major pest impacting cotton and other malvaceous crops worldwide. Originating in Africa, it has spread to Europe, the Middle East, Asia, South America, and the Caribbean. CSB infestations reduce oilseed production, seed germination, and cotton seed weight, posing significant agricultural challenges. However, developing effective control measures is complex due to limited understanding of the CSB’s chemical communication.

To address this knowledge gap, we measured the orientation responses of 4th/5th instar nymphs, adult males, and females (mated and unmated) to whole-body nymph solvent extracts using a Y-tube olfactometer assay. Results showed that 4th/5th instar nymphs and mated females were significantly attracted to the nymph extract side compared to the hexane control arm. Conversely, unmated males, unmated females, and mated males preferred the hexane control arm. A dual-choice refuge assay confirmed these findings, with mated females and nymphs seeking refuge on cotton seeds placed above exuviae extracts, while unmated individuals and mated males preferred the cotton seeds located on the hexane control side. Furthermore, a dual-choice oviposition assay revealed that mated females laid significantly more eggs on cotton seeds positioned above the nymph extracts, likely because nymph odors signal suitable feeding sites for smaller nymphs. These findings suggest that nymph-associated odors attract both conspecific nymphs and mated females for oviposition. Identifying the chemical components driving this attraction could enable the development of lures, a key strategy in integrated pest management (IPM) for effectively controlling CSB infestations.