Recently at the Entomological Society of America annual meeting in Knoxville, TN, University of Florida researchers presented findings on 15 insecticidal baits evaluated for an integrated pest management system tailored to crazy ants (Nylanderia fulva), an invasive that can establish colonies with multiple queens and millions of workers, blanketing lawns and sidewalks, killing native species, shorting out electrical systems, and creating headaches for homeowners, farmers, and pest-control operators.
Crazy ants are present in Florida and several other Gulf Coast states. Currently, 20 Florida counties have reported invasive crazy ant colonies, with Sarasota County hardest-hit. Texas, Mississippi, and Louisiana also have experienced problems with them, which probably arrived in the U.S. 10 to 20 years ago via soil or plant material transported on ships.
Though the ant does not pack a painful bite or sting, scientists are concerned that it could gravely impact Florida’s agricultural industries if it enters agricultural systems, said Faith Oi, a UF/IFAS assistant Extension scientist. In Colombia, where the species has been established for decades, harvests sometimes are negatively impacted by the overwhelming presence of crazy ants in crop fields.
The species is often referred to as the “Caribbean crazy ant,” but it appears that name may be misleading. Until recently it was thought that well-publicized infestations in Florida were caused by a species present in the state for half a century, N. pubens. But a research paper published this year showed that the crazy ants swarming in Jacksonville and Gainesville were actually the species N. fulva. Oi said it’s likely that some, if not all, Gulf Coast infestations are caused by this species, which hails from South America.
So far, efforts to control crazy ants have involved a patchwork of approaches, many of which failed.
Though none of the products were developed specifically for crazy ants, the researchers found that two granular baits – Amdro Pro (BASF) and Maxforce Complete (Bayer Environmental Science) killed crazy ants fastest in laboratory testing, probably because those baits had the most “appetite appeal” and were eaten more readily than other products, said Dawn Calibeo, an entomology doctoral candidate with UF/IFAS. “There’s not the ideal combination of bait and class of active ingredient we’d like,” Calibeo said. “Most of the formulations we tested were developed for fire ants, which feed on fats, so they contain oil. Crazy ants hate oil.”
It will be several months before full recommendations are ready, she said. But, based on her studies of crazy ants’ feeding and nesting habits, Calibeo has developed some preliminary suggestions for pest-control professionals:
First, it’s crucial to attack the problem early in the year, preferably in February or March before the weather warms up and the ants begin breeding. She says to “bait early and bait according to label directions.” Professionals should use baits after applying a contact insecticide to reduce ant numbers, but be careful not to place baits where they’ll be contaminated by contact insecticides.
Funding for the research was provided by the USDA and Bayer.