Mexican Fruit Fly Threatens Organic Farms

CHURCHVILLE, VA—The organic food industry is facing disaster. The Mexican fruit fly has broken through California’s pest defenses and could infest most of California’s fruit crops with voracious, wriggling maggots. Hundreds of California’s organic fruit and vegetable farms—the world’s largest concentration of organic-agriculture production—might have to be quarantined at the height of the winter selling season.

California has no choice but to do whatever is necessary to stop the invasion. Governor Gray Davis said that the flies might wipe out California agriculture “as we know it.” The United States would then lose its biggest source of off-season fruits and vegetables, and this would bring major health risks. Eating five servings of fruit or vegetables per day reduces your cancer risks by half, regardless of whether the produce is raised organically.

In the past, California fended off fruit fly invasions by spraying synthetic pesticides such as malathion. But malathion violates the rules of organic production. If California were to spray the pesticide on the state’s organic fields, it would be next summer before large supplies of non-California organic produce could become available again, and several years before the California producers could again qualify for the new U.S. Department of Agriculture Certified Organic seal.

Organic-centered Whole Food and Fresh Fields supermarkets would face an unpleasant dilemma. Either they would have to close their doors for lack of organic produce, or they would have to tell their customers that produce sprayed with approved synthetic pesticides is safe to eat—just less expensive and less trendy. It’s true, but not exactly good marketing for them.

Ironically, the organic food industry will be spared from making these awful choices, thanks to one of the great bugaboos of the organic farming industry: a big chemical company. Governor Davis put in an emergency call to Dow AgroSciences and demanded thousands of pounds of its new organically accepted Naturalyte Fruit Fly Bait, which contains the active ingredient spinosad. The fruit fly suppression campaign will mean little to Dow Chemical’s profits, but it is likely to save the California organic-farming industry.

Spinosad is fermented from natural soil bacteria, and it offers both the pest-killing effectiveness of the best synthetics and the safety profiles of near-benign biological pest controls. Spinosad is not only natural, but is applied at ridiculously low rates—typically one hundredth of an ounce per acre. This tiny amount of pesticide is mixed with bait—six cups of sugar and corn protein per acre, plus U.S. Department of Agriculture-identified attractants that fruit flies love—to lure the creatures into ingesting a fatal dose.

Humans and mammals would have to ingest at least two thousand times the spinosad application rate to incur any danger. Spinosads are low in toxicity to humans and mammals, practically non-toxic to birds, and only moderately toxic to fish. They are tailored to attack the physiologies and enzymes of insects. Moreover, fruit flies have to eat the bait for it to work, so it poses little risk from contact exposure to beneficial insects. In addition, bees are repelled by its odor.

Development of resistance in the target species isn’t an issue here. The job at hand is eradication, not suppression, which means that the flies’ offspring must also be killed. Fruit-fly maggots fall to the ground with the ripe fruit and burrow into the soil to wait for several weeks as pupae before emerging as adult flies and renewing the infestation. Thus, the state will require a series of sprays to protect the produce, and often the areas under the trees will have to be sprayed labor-intensively, using backpack and ATV sprayers.

Ironically, California’s traditional weapon against fruit flies has been another supposed evil usually hated by organic-farming advocates: radiation. Every year, as both the Mexican and Mediterranean fruit flies try to attack California fruit orchards, they are stymied by millions of lab-raised male fruit flies that have been sterilized by gamma rays and released each year across the southwestern U.S. and northern Mexico. The sterile males mate with fertile females, and the latter produce no offspring, which suppresses the fly populations.

This year, when the irradiation defense proved inadequate and the Mexican fruit flies managed to mount dangerous invasion numbers, the research investment of a big chemical corporation appears to be the only plausible salvation for the organic produce industry.

The spraying effort has just started. Let’s hope that it can survive the usual onslaught of anti-pesticide activists waving injunctions and of black-clad anti-corporation activists smashing spray-plane windshields with baseball bats. If they succeed in blocking the program, the tiny fruit fly might close down the U.S. organic food industry permanently.