Cotton Seed Volatiles Functioning as Host-Seeking Cues for the Oxycarenus hyalinipennis (Hemiptera: Lygaeidae)

The cotton seed bug (CSB) (Oxycarenus hyalinipennis), an emerging pest of cotton worldwide, causes significant economic damage through seed feeding and fiber contamination. Effective monitoring tools for this species are currently lacking, limiting the implementation of integrated pest management (IPM) strategies. In this study, we characterized the volatile profile of whole, unprocessed cotton seeds and evaluated the behavioral responses of adult CSBs to individual compounds and synthetic blends. Using gas chromatography-mass spectrometry (GC-MS) analysis, we identified 17 volatile compounds, including aldehydes, hydrocarbons, aromatic compounds, terpenes, ketone, and fatty acid ester. Y-tube olfactometer assays revealed that only four individual compounds, 1-heptanal, 1-decene, 1-nonanal, and isopropyl palmitate, elicited significant attraction from both males and females. Chemical blends of these four compounds formulated in a natural ratio (1:16:4:2) and an equal ratio (1:1:1:1) demonstrated strong, dose-dependent attraction, with optimal responses occurring at low doses (0.01 µg). Robust behavioral attraction was observed in response to the complete four-component blend. Removal of any individual compound significantly reduced attraction in a sex-specific and dose-dependent manner. Notably, removal of the fatty acid ester isopropyl palmitate from the blend almost resulted in a complete loss of attraction. This study provides the first comprehensive characterization of volatile emissions from whole cotton seed and presents the first evidence in CSB that 1-decene and isopropyl palmitate function as key volatile components of the foraging cue for attraction. These findings advance our understanding of CSB chemical ecology and highlight the potential of dose-dependent, multi-component kairomonal blends as tools for monitoring and management of CSB.