Virus-induced feeding behavior changes reduce baiting efficiency in red imported fire ants

The red imported fire ant, Solenopsis invicta Buren, is an invasive species that causes significant economic and ecological damages in their introduced ranges. Baiting is the primary control strategy against fire ants but requires workers to transport bait back to the colony until lethal doses are consumed. However, recent findings show that viral infection, while generally asymptomatic, reduces foraging activity of fire ants. This raises concerns about the effectiveness of baiting in virus-infected ants as reduced bait intake may compromise worker mortality and delay colony elimination. To explore this fire ant-virus-baiting tripartite interaction, we first compared worker mortality in virus-infected and uninfected colonies under laboratory conditions and showed that virus-infected colonies exhibited significantly lower worker mortality compared to uninfected colonies. We then conducted field tests in which sites with varying prevalence were treated with bait broadcast. Our results show that more inactive colonies were observed after baiting at sites with moderate virus prevalence (50-60%) than at sites with high virus prevalence (90-100%). These findings not only improve our understanding viral impacts on fire ant foraging behavior and provide insights for optimizing fire ant baiting strategies.