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Fire ants contribute to decline of wildlife
STARKVILLE, Miss. -- Blake Layton grew up quail hunting in Simpson County and has seen the steady decline of quail as fire ant populations expanded across the state.
Layton, an entomologist with the Mississippi State University Extension Service, said the farm he grew up on has the same habitat as it did when he was a child, but it has more fire ants and fewer quail and other wildlife species.
“When I was younger, I’d go into a pasture, and Eastern meadowlarks were everywhere. Now they are much less common,” Layton said. “The serious birders around the state agree there aren’t as many.”
Fire ants originated in the open, savannah-type habitats of South America.
“That’s why they come to our ball fields, pastures, parks and open habitats,” he said. “Meadowlarks and quail nest in those same areas. You’ll see quail on the edges of heavily wooded habitat, because fire ants are less likely to do well in the trees. There is less for them to forage.”
Fire ant colonies send foragers everywhere looking for protein, oils and carbohydrates. When they come upon a nest of young birds, they see a major food source and recruit other ants to help.
“I’ve seen fire ants accumulate around the fluid coming out of an egg just as the hatchling is starting to make its way out of the shell. By the time it hatches, the nest is under a full-scale attack,” Layton said. “Newly hatched birds are so vulnerable, they are extremely susceptible to fire ants.”
Tim Lockley, now a senior entomologist with the Mississippi Department of Agriculture and Commerce, spent more than 20 years with the U.S. Department of Agriculture researching fire ants. He conducted numerous studies across the Southeast on the impact of fire ants on threatened species, as well as game species.
From gopher tortoises on Camp Shelby in Hattiesburg to the Florida grasshopper sparrow, Lockley has discovered just how opportunistic fire ants are.
“We saw extensive reduction in whatever the target animal was when fire ants were present,” Lockley said. “Field mice, snakes, alligators and not just ground-nesting birds. I’ve seen fire ants nest in the leaf litter mulch between major branches of a pecan tree and prey on birds’ nests high in the trees. If they can get to it, fire ants will kill it or cause it to die from secondary effects.”
Rabbits do not move right after they are born, which means they cannot escape fire ants. Fawns freeze when they sense danger, which is good when a coyote is approaching but ineffective when the predator is a foraging party of fire ants.
“Ant stings can blind the fawn and cause swelling around the mouth and tongue until it starves to death,” he said. “If cattle or sheep give birth on a mound of fire ants in a pasture, the offspring likely won’t survive.”
The good news is fire ants are relatively inexpensive to treat, and the treatment is effective.
Lockley’s research on the Gulf Coast least tern showed a 42 percent increase in hatchling survival in an area of beach treated for fire ants versus one that was not treated.
“Bait is very cheap on a per acre basis, and it’s extremely safe, though you won’t get instant gratification,” Lockley said. “Amdro, the most commonly used, is a slow-acting stomach poison. Some other baits don’t have a poison. Instead, they have an insect growth regulator that sterilizes the queen. She stops creating more fire ants, so the mound will die over time from attrition.”
Layton said granular fire ant baits can be applied to large areas with an airplane, but most people use a Herd seed spreader.\
“Don’t use a fertilizer spreader,” he cautioned. “You need something with a low rate of distribution.”
With pastures, Layton said landowners and managers will see benefit from one application per year. For wildlife restoration, two applications a year are more effective.
“After that, it depends on how serious you are and how much you want to spend,” he said. “Always follow label instructions for how many times you can apply it -- typically two to four times.”
To access several Extension publications related to fire ants, visit http://extension.msstate.edu/bite-back.