Jake Farnum, Bugwood.org

The red imported fire ant is more than a nuisance. Besides its painful sting, control costs and damage to U.S. urban, agricultural, wildlife, recreational, and industrial areas are estimated at $6 billion per year.

The USDA Animal and Plant Health Inspection Service (APHIS) has imposed a quarantine, mainly in southeastern states, to help limit the fire ant’s spread. The ants have infested 300 million acres since they were introduced into the United States in the 1930s. A quick way to identify these invasive pests is sorely needed.

Agricultural Research Service (ARS) scientists at the Center for Medical, Agricultural and Veterinary Entomology (CMAVE) in Gainesville, Fla., and APHIS in Biloxi, Miss., have a solution.

Entomologist Steven Valles, who works in CMAVE’s Imported Fire Ant and Household Insects Research Unit, developed novel antibodies that bind to a protein in the fire ant’s venom. Working with APHIS laboratory director Anne-Marie Callcott and CMAVE entomologist Charles Strong, Valles used these antibodies to develop a portable, easy-to-use test kit that identifies red imported fire ants in 10 minutes. Currently, identifying ants found at inspection stations takes hours or even days, because samples are typically sent to a lab.

This map predicts areas in the United States that are susceptible to invasion by the red imported fire ant, Solenopsis invicta. Predictions are based on climate and current northernmost distributions of red imported fire ants. Results of the model predict that red imported fire ants will likely move 50-100 miles north in Oklahoma and Arkansas. They will also likely continue expanding into portions of Virginia, Maryland, and Delaware in the east and New Mexico, Arizona, California, Oregon, Nevada, and maybe even Washington and Utah in the west. Source: USDA

“Trucks carrying hay, nursery stock, soil-moving equipment, or other items are inspected when they leave a quarantine area and head for an area not under quarantine,” Valles says.

If ants are detected, the shipment must remain within the inspection or holding area until ants are identified.

“The wait could be hours if an expert has to identify the ant species from a photo, or it could take days if an ant sample has to be sent to a lab,” Valles says. “The new test fixes that problem.”

The test kit does not require any special training to use. It contains a plastic tube, a pestle to mix in ants, and a test strip that detects red imported fire ant venom. If the strip has two lines, the test is positive. If it has one line, it is negative.

This technology was developed primarily for APHIS’s use at truck inspection stops, but could be used at other locations where cargo is imported or exported, Valles says. The USDA has obtained a biological material license for the test’s antibodies, which specifically identify red imported fire ants.

Sandra Avant is with the ARS Office of Communications.