As winter melts into spring and Southland residents spend more time outside, a pest management expert Tuesday warned people to keep a close eye out for red imported fire ant colonies on lawns, parks, playgrounds and golf courses in Los Angeles and Orange counties.
The red imported fire ant arrived in California in 1989, and is now widespread in residential and commercial areas of Orange, Riverside and San Bernardino counties, as well as adjoining areas of Los Angeles County, according to UC Agriculture and Natural Resources.
True to their name, fire ants inflict painful, burning stings when they crawl onto people working, walking or resting on infested turf grass and other outdoor areas. For some people, fire ant bites and stings can lead to life-threatening anaphylactic shock.
RIFA colonies look like mounds on the ground that resemble gopher holes because they consist of a circular upwell of loose soil. The ants are difficult to eradicate.
Siavash Taravati, an UC Cooperative Extension integrated pest management adviser, is looking to reduce the population and minimize the risk of injury the ants can cause.
Taravati helped the California School for the Deaf in Riverside control an exploding RIFA population on its 70-acre campus, and turned the effort into a research project with results that he said can help other Southern California agencies deal with RIFA infestations.
“The School for the Deaf’s grounds crew was struggling to control RIFA, but had little success,” Taravati said, noting that the liquid pesticide used there only offered temporary relief.
With financial support from the California Department of Pesticide Regulation, Taravati evaluated some of the most common products available for RIFA control, including commercially formulated corn grits coated with soybean oil containing pesticide.
He used two different school sites and marked 35 locations of RIFA activity with construction flags and spray paint, then treated areas with various pesticides, and monitored them for a year. The pesticides he used contained indoxacarb, hydramethylnon s-methoprene, and boric acid.
“After a few months, the number of RIFA mounds were reduced by 96% in the some of the most problematic areas,” Taravati said. “Even when new mounds appeared on the lawn, they were always small in size.”
The RIFA control guidelines that Taravati introduced were adopted by the school staff to maintain a safe environment for the school’s 500 students. He said the work done there has applications that can help other sites reduce the risk of ant stings.
“Many pesticides for RIFA control are designed and marketed to professional applicators, but there are some that residents can purchase in home stores or online,” Taravati said, noting that children must be kept away from the treated areas during and immediately after applications because touching or eating fire ant granules might be harmful to people.
More information about RIFA pesticide options are spelled out at ipm.ucanr.edu/PMG/PESTNOTES/pn7487.html.
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