Kent Demaret August 03, The fast-reproducing Medfly, which spoils produce by laying its eggs in the crops, might have been eradicated last year had aerial spraying been undertaken with the pesticide Malathion. Instead, bowing to pressure from environmentalists, California Gov. Jerry Brown chose to rely on less provocative measures, including ground spraying and releasing sterile male flies to cut down on offspring.
But this summer, following a massive new Medfly infestation, Agriculture Secretary John Block threatened to quarantine all susceptible California fruit, and Brown finally agreed to aerial spraying. Like many scientists, Perry L. Gilstrap, 37, an associate professor of entomology, had studied the Medfly in Central America. Why has a month campaign failed to bring the Medfly under control? California has mishandled the fruit fly problem from the beginning. The Medfly destroys all citrus crops, pitted fruit and many vegetables.
Only leafy vegetables and ground crops like carrots and potatoes are safe. The politicians knew that a year ago, but they just dillydallied around. How did the effort fall short? Last summer, after the fly was first discovered, officials established the smallest possible quarantine zone they could—about square miles. They did not regulate private traffic there to make sure no infested produce got out.
And they did not immediately go to aerial spraying. What role has Governor Brown played in this crisis? Early this year I was asked to join his California Medfly Technical Advisory Committee, which had been formed last year. After the latest Medfly outbreaks, in late June, we unanimously recommended immediate aerial spraying of Malathion. Called to Sacramento, we sat right across from Governor Brown.
Face to face, I personally explained the urgency of the situation. Jerry Brown told us he had already decided to stick with ground spraying. It was a charade. In California, however, the affected areas have not been the farms but the suburban residential counties south of San Francisco.
So people have a fear. How dangerous is Malathion? In the dosages being used in California it is nontoxic to mammals. And it breaks down in about three days to harmless biodegradable materials.
There is nothing better than Malathion right now. How does it work? People, however, have in their livers a powerful enzyme that renders it harmless. Unlike DDT, though, Malathion does not get worse and worse as it goes up the food chain, becoming more concentrated in each higher level of animal. How long has Malathion been in use? In , to combat a Medfly infestation, it was sprayed repeatedly over the entire city of Miami, and no ill effects have ever been reported.
Then why was there such an outcry among environmental groups? Some of these people, though well-meaning, are misguided. Stripping fruit and ground spraying worked in the Los Angeles area, but not farther north. The area to the north is much larger. Some are behind locked gates. Bear in mind that each female Medfly can lay up to eggs, producing a new generation in three weeks. And for the first six months after the flies were discovered—on June 5, —the major effort in the San Francisco area, along with stripping and ground spraying, was releasing millions of sterile flies.
That has never been shown to be an eradication tool anywhere in the world. The principle is that the female will mate only once, so by releasing thousands of males sterilized by radiation you increase the odds that the female will mate and produce no eggs.
It works well when the fly population is very, very low. You both sound as if you consider pesticides a panacea. We advocate what is called integrated pest management, in which pesticides are a second line of defense. The first involves—among other things—crop rotation so the pests will die when their food is cut off, developing fast-growing and pest-resistant strains of plants that literally outrun pest attacks, and introducing biological control agents.
What are biological control agents? The ancient Chinese used to stretch bamboo poles between the branches of citrus trees so that ants could walk from one to another and eat destructive pests.
A certain kind of wasp. Where is this wasp found? Back where the Medfly hails from—Africa. They are not like our familiar wasps, but tiny things about the size of gnats. By this time next year, we should have a natural predator for the pest. Once the Medfly has infested an area, can it ever be entirely eliminated? Yes, depending on quick detection and response.
In California, the jury is still out on whether the Medfly is now a permanent resident. You May Like Get your People daily dose Subscribe to the daily newsletter for the latest celebrity news.