UCR study shows two common ant baits trigger opposite behaviors before killing Argentine ants
Researchers at the University of California, Riverside discovered that thiamethoxam and boric acid baits cause invasive Argentine ants to behave very differently before the insects die.
A team led by entomology professor Dong Hwan Choe at the University of California, Riverside examined how Argentine ant colonies respond to two widely used bait insecticides, thiamethoxam and boric acid. Transparent laboratory nests allowed observation of ant movements; thiamethoxam triggered heightened activity and outward roaming before all workers died within about seven days, likely due to its nicotine-like overstimulation of the nervous system.
Boric acid produced the opposite effect, suppressing foraging and causing ants to gather tightly inside the nest, often near water sources, and eliminating about 90% of workers over roughly two weeks. The researchers warned that killing workers may not eradicate a colony if the queen remains, and that food sharing among ants can reduce individual insecticide exposure, potentially extending sublethal effects. No resistance to these chemicals has been documented, but Argentine ants remain a challenging pest to control.
Why it matters
Understanding bait effects helps homeowners and pest managers avoid misreading ant activity and improves control strategies for invasive species.
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