Dr James Heitz
Battle Against Fire Ant By DOUGLAS R. SEASE JACKSON. Miss. (UPI) - Flourescent dyes that kill common common houseflies when exposed to light are being studied by researchers in Mississippi as possible way to control one the South's most vicious pests, the imported fire ant. Dr. James Heitz, a biochemist biochemist at Mississippi State University, University, believes xanthene flourescent dyes may soon replace the chemical pesticide Mirex in the fight to control the tiny ants, whose rockhard mounds now dot millions of acres of Southern farm and pastureland. "One of my associates got the idea that the dyes might work on fire ants when he read about some other researchers using it to kill houseflies," Heitz said in an interview. "He tried a simple uncontrolled experiment experiment and when it appeared to work, he passed the idea along to me." Mirex has been used for several years against the ant. whose excruciating sting has been known to kill human beings, but the chemical has run into strong opposition from environmentalists. They claim it may cause cancer and is polluting the South's lakes, streams and coastline. Heitz found in the laboratory that he could induce a nearly 100 per cent mortality rate by feeding the ants food impregnated impregnated with the xanthene dyes, then exposing them to light. According to Heitz. the energy contained in the light filtering through the ant's body wall begins a reaction called "photo-oxidation" which releases releases high-energy oxygen molecules from the dye compound. compound. The oxygen molecules attack and destroy the enzyme acetyl- cholmesterase. which is essential essential to the functioning of all biological nerve systems. As the enzyme is destroyed, the ant's nerve system simply shuts down, halting such vital functions as respiration, circulation circulation and brain activity. "But a light reaction alone wouldn't be enough to control fire ants like Mirex does," Heitz pointed out. "The key controlling them lies in reaching reaching the queen." Since the queen stays secluded secluded deep in the dark recesses of the nest, a light reaction would be ineffective against her. Mirex works because ants love it. The worker ants will harvest harvest it and carry it to the queen who eats it and dies, thus eliminating the source of hundreds hundreds of thousands of new fire ants. Heitz has found, however, that xanthene dyes also produce produce a "dark reaction." Even without light the dye is deadly to the ants, although the process, probably closely related to conventional pesticide poisoning, is considerably considerably slower than photo- oxidation. "If the worker ants who eat the dye live long enough to reach "the queen, she'll ingest it and die. too." Heitz contends. "The xanthene dyes are the equal of Mirex in their potential potential for killing the ants and they have one important advantage," advantage," he said. "While Mirex is so darn stable that it last virtually virtually forever, the xanthene dyes will break down into simpler compounds within about two weeks." Heitz is now hoping to get funding that will enable him to carry on large scale experiments experiments on private lands leased to the university near the Starkville campus.' If the fire ant program is successful, he believes it can be adapted to combat other agricultural pests including the boll weevil, the tobacco budworm budworm and the southern pine beetle, all of which cause untold untold damage to southern crops every year.