Study on the influence of adding NaCl on the storage period and trapping efficacy of monitoring baits for Solenopsis invicta

Red imported fire ant (Solenopsis invicta Buren) is recognized as one of the world's 100 most detrimental invasive species, posing substantial threats to agricultural and forestry production, human and animal health, public safety, and biodiversity. Accurate and effective monitoring of S. invicta is critical for its prevention and control, with bait trapping being a widely used monitoring method. In this study, 5%, 10%, and 15% sodium chloride (NaCl) were added to a pre-developed specialized monitoring bait to investigate their effects on the bait's storage period and trapping efficacy against S. invicta, with the aim of further enhancing bait performance. Results showed that higher NaCl concentrations significantly delayed deterioration in bait color and odor indicators, suggesting that NaCl retards bait spoilage.Indoor tests revealed that the trapping efficacy of S. invicta generally decreased with prolonged storage. Specifically, the 5% NaCl treatment showed significantly higher trapping efficacy than the NaCl-free control from day 19 to day 25. The 10% NaCl treatment only showed significant superiority on days 19 and 22, while the 15% NaCl treatment was significantly more effective only on day 16. Outdoor field trials indicated no significant differences between NaCl treatments and the control within the first 20 days. However, on day 30, the 5% NaCl treatment exhibited significantly higher trapping efficacy than other treatments and the control. In conclusion, bait with 5% NaCl addition demonstrated optimal performance in both storage period and trapping efficacy, providing a scientific foundation for the development of precise, efficient, and cost-effective monitoring baits for S. invicta.