Development and Demonstration of Low-Impact IPM Strategy to Control Argentine Ants (Hymenoptera: Formicidae) in Urban Residential Settings

Ants evade harmful food by active abandonment

Invasive ants, such as the Argentine ant, pose a severe economic and ecological threat. Despite advancements in baiting techniques, effectively managing established ant populations remains a daunting challenge, often ending in failure. Ant colonies employ behavioural immunity against pathogens, raising the question of whether ants can collectively respond to toxic baits. This study investigates whether ant colonies actively abandon palatable but harmful food sources. We provided two sucrose feeders, each generating a new foraging trail, with one transitioning to offering toxic food. Six hours later, ant activity on that path decreases, while activity on the non-toxic food and the trunk trail remains unaffected, excluding factors like population decline or satiation as reasons for the activity decline. Laboratory experiments confirmed that ants remained alive six hours after ingesting toxic food. Ant presence remains low on the toxic food path for days, gradually decreasing along the nearest section of the trunk trail. This abandonment behaviour minimises the entry of harmful food into the nest, acting as a protective social mechanism. The evasion of toxic bait-treated areas likely contributes considerably to control failures. Understanding the behavioural response to toxic baits is essential for developing effective strategies to combat invasive ant species.

Laboratory evaluations of biodegradable boric acid hydrogel baits for the control of Argentine ant (Hymenoptera: Formicidae)

Due to their mutualistic relationship with plant pests, the Argentine ant is considered a major pest in subtropical fruit orchards and vineyards. Besides insecticide sprays, liquid baiting has been demonstrated as an effective method to suppress the Argentine ant populations. To improve the economic feasibility of liquid baiting, hydrogel materials have been recently tested as a carrier for liquid baits containing various insecticidal active ingredients. Here, we tested boric acid as a toxicant in the aqueous sugar bait delivered in a biodegradable calcium alginate hydrogel. Laboratory tests demonstrated that boric acid (1%) liquid bait incorporated in the calcium alginate hydrogel effectively killed Argentine ant workers. Potassium sorbate (0.25%) added to the liquid bait as a preservative did not impact the efficacy of boric acid even though it significantly reduced the degree of swelling of the hydrogel beads in the bait solution. Testing with 2-month-old bait suggested that long-term storage might impact bait efficacy even with potassium sorbate preservative.

Highlights of Urban Entomology 2021: Chemical, Nonchemical, and Alternative Approaches to Urban Pest Management as We Adapt, Advance, Transform

The 2021 annual meeting of the Entomological Society of America with the theme of "Adapt. Advance. Transform" guided the highlight compilation of urban entomology papers. Integrated pest management of urban pests relies on techniques and tools that adapt, advance, and transform over time to develop into new usable tactics and technologies; the review covers the following three themes: first, how science, researchers, and pest management professionals adapt to the changing environments; second, how urban pest management approaches and technologies advance using conventional and alternative strategies; and last, how transformation happens, leading to technological advances and sustainable pest management success. I selected papers on four groups of urban pests-ants, termites, bed bugs, and cockroaches-that were in the context of pest management in this highlights publication. Emphasis was placed on research regarding the efficacy of chemical (e.g., conventional pesticides, insect growth regulators), nonchemical, and alternative approaches (e.g., the use of heat, naturally derived compounds) for urban pests that help improve and implement sustainable pest management plans. These papers demonstrate the achievements of the urban entomology community while emphasizing the current challenges that we face from the far-reaching impact of climate change and insect pest adaptation and what should be prioritized.