Effect of fast and slow-acting bait toxicants on tawny crazy ant (Hymenoptera: Formicidae) foraging and nesting in the field

Authors: Oi, David; Atchison, Rachel; Read, Quentin

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/16/2024
Publication Date: 12/21/2024
Citation: Oi, D.H., Atchison, R.A., Read, Q.D. 2024. Effect of fast and slow-acting bait toxicants on tawny crazy ant (Hymenoptera: Formicidae) foraging and nesting in the field. Journal of Economic Entomology. 118(1):329-338. https://doi.org/10.1093/jee/toae284.
DOI: https://doi.org/10.1093/jee/toae284

Interpretive Summary: Tawny crazy ants (TCA) are an invasive species from South America that develop extremely large populations that overrun landscapes and invade buildings. Control measures frequently rely on spraying insecticides over infested areas which often is inadequate. Baits are an effective and environmentally compatible way to control pest ants because they utilize the natural feeding behavior of ants to distribute active ingredients in baits to ant colonies via food sharing. However, currently available baits are often not effective on TCA due to TCA food preferences and repellency of the active ingredients. To improve baits for their control, TCA feeding behavior was compared among liquid ant baits that contained either a fast-acting (dinotefuran) or a slow-acting (boron-based) active ingredients, and a control of sugar solution. Counts from time lapse photography of TCA feeding on the baits under field conditions, revealed strong evidence of similar feeding intensities between the control and the slow-acting bait which fed until baits were depleted. Much less feeding occurred on the fast-acting bait. The impact of the fast and slow-acting baits on TCA in field plots were determined by rating TCA nest sizes and counting TCA feeding on food lures. Statistical predictions based on the field plot data revealed nest sizes declined over the 2 months when either bait was available while the control had large nests. TCA abundance on the lures in the fast-acting bait plots declined from the start of the study while with the slow-acting bait, declines in abundance were not evident until 30 days after baiting was initiated. The greater consumption and slow-action of the boron-bait suggested that it may be distributed to TCA colonies beyond the field plots and perhaps can slow reinvasions. In contrast, the fast-acting bait can result in fast, localized control. Strategic bait placements to take advantage to of the slow- and fast-acting bait properties may provide fast and sustained control of TCA.

Technical Abstract: Tawny crazy ants (TCA), Nylanderia fulva (Mayr) are an invasive species that develops extremely large populations that overrun landscapes. Control measures frequently rely on spraying contact insecticides which often are inadequate. To provide insights for utilizing baits for their control, TCA foraging behavior was examined on liquid ant bait formulations that contained either fast-acting dinotefuran or slow-acting disodium octaborate tetrahydrate (DOT), and impacts of these baits were assessed. Bayesian modeling of counts from time lapse photography of TCA feeding on the baits and a control of sucrose solution in the field, revealed strong evidence of similar foraging intensities between the control and the DOT bait and less foraging intensity on the dinotefuran bait. TCA abundance on the dinotefuran bait peaked within 8 hours, then diminished to smaller feeding bouts over the 3-day study. In contrast, foraging on the DOT and control remained consistently high before bait depletion. The impact of the fast and slow-acting baits in field plots were based on TCA nest sizes and TCA abundance on sausage lures. Bayesian modeling predictions revealed nest sizes declined over the 2 months with bait present while the control had large nests. Abundance on the lures in the dinotefuran plots declined from the start of the study while with the slow-acting DOT bait, declines in abundance were not lower than the control plot until 30 days after baiting was initiated. Further refinements in baiting with liquid baits containing fast and slow acting active ingredients may provide fast and sustained control of TCA.