Identification and optimization of volatile organic compounds to enhance bait attractiveness for red imported fire ants (Solenopsis invicta Buren)

Abstract

BACKGROUND

The red imported fire ant (RIFA, Solenopsis invicta), a highly destructive invasive pest, has rapidly spread through human trade, posing significant threats to agricultural and forest ecosystems. Due to its preference for high-fat and high-protein foods, ham sausage is commonly used as bait to monitor RIFA populations in invaded areas. However, the presence of volatile organic compounds (VOCs) in such baits may affect their effectiveness because VOCs can act as either attractants or repellents. Identifying VOCs that specifically attract RIFA is essential to improve bait efficacy.

RESULTS

This study aimed to identify attractant compounds within bait VOCs for RIFA, leveraging the highly-expressed antennal odorant-binding protein 1 (OBP1) and reverse chemical ecology approach. Additionally, we examined the effects of mixtures of these attractants on RIFA behavior. Our findings revealed that anethole, 1S-(−)-β-pinene, and β-caryophyllene individually attracted RIFA at 0.1 μg/μL. Notably, a combination of anethole and 1S-(−)-β-pinene enhanced behavioral activity more than individual compounds, suggesting synergistic effects. Conversely, the addition of β-caryophyllene to anethole significantly reduced RIFA activity. These results provide a theoretical basis for developing behavioral regulators targeting RIFA.

CONCLUSION

This study demonstrates that the integration of OBP-based in vitro assays with computational simulations can effectively identify behaviorally active compounds for RIFA. Additionally, it clarifies the optimal ratios of active VOCs in baits, offering valuable theoretical guidance for enhancing RIFA population monitoring efforts. © 2025 Society of Chemical Industry.