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Public Radio's Environmental News Magazine (follow us on Google News)

Mitigating Medflies

Air Date: Week of

The Mediterranean fruitfly is one of the most destructive agricultural pests in the world. In Mexico, a program to control the medflies is raising concerns among farmers and residents. Tatiana Schrieber reports from Chiapas.


CURWOOD: The Mediterranean fruit fly is one of the most destructive agricultural pests. Medflies can attack as many as 200 kinds of fruits and vegetables, and their hatching eggs can ruin tons of produce in a short amount of time.

For three decades, the United States, Mexico, and Guatemala have cooperated in a program to eradicate the bug. In Mexico it’s called the Moscamed program and it claims great success in controlling medfly outbreaks. But as Tatiana Schreiber reports from Chiapas, it’s been controversial.

SCHREIBER: The Mayan Indian coffee farm and community of Peña Blanca is just outside the Montes Azules Biosphere Reserve in southeastern Mexico. It’s some of the last remaining rainforest in the Americas. And while some environmentalists see all farming in this fragile ecosystem as destructive, organic, shade-grown coffee is considered one of the most environmentally benign ways to use the land.


SCHREIBER: Don Manuel de Jesus Ruiz names the various shade trees that protect his coffee, and whose fallen leaves create the rich compost on the ground. Don Manuel has just one hectare, about two and a half acres, planted with coffee along with banana, guava, avocado, and citrus trees. He points to many with damaged or completely missing leaves.

DE JESUS: [SPANISH] Look at these trees! They shouldn’t be like this. They should have their normal leaves. The fumigation affected them so much. Look at those, they don’t have leaves. They are completely ruined.

SCHREIBER: Don Manuel and other farmers here are furious about what they say is a threat to their livelihoods, to their attempts to farm organically, and to the ecology of the area. Two or three years ago, medflies were detected in southern Mexico which had been free of the pest since the early 80s. The government response was to go on the offensive. The first step was aerial insecticide spraying, followed by the release of millions of sterilized medflies to halt reproduction.

From 1978 through last year, the Moscamed program’s insecticide of choice was Malathion. Agronomist Pablo Muench Navarro is director of the Institute of Natural History and Ecology for Chiapas. He says Malathion is not known to defoliate trees. But after a visit to the region, he believes the farmers’ complaints have merit.

MUENCH: [SPANISH] In my opinion, there is damage to the coffee trees and the shade trees from the spraying. In addition, it appears to me that the substances they are using are strong, strong agrochemicals.

SCHREIBER: Muench speculates that perhaps an error, like the use of the wrong concentrations of the chemical, could be at fault. Medfly officials attribute the problems to severe drought followed by heavy rains.

Aside from defoliation, farmers also complain that the spraying caused their fruits to be small, to mature and rot early, and to have dramatically reduced yields. They also point to an explosion of worms in their fruit and new outbreaks of pests such as the coffee borer.

Helda Morales is a specialist in biological control of pests. She says if large numbers of beneficial insects, including pollinators and natural enemies of pests, were killed off by the insecticide, these are just the kinds of results farmers might see.

MORALES: [SPANISH] It could have had an effect both in terms of lower yields of fruit and an increase in pests, not only with worms, like those of fruit flies, but also many others.

SCHREIBER: In 2001, the Moscamed program switched from Malathion to Spinosad, which it claims, is less toxic to non-target insects. According to U.S. EPA documents, however, Spinosad, too, is highly toxic to beneficial honeybees.

Along with concerns about the environment, some local residents fear the Moscamed program has political goals.


SCHREIBER: Monte Flor is another primarily Indian community not far from Peña Blanca. This part of Chiapas is home to the Zapatistas, a rebel movement that staged a military uprising in 1994. Zapatistas here have formed their own autonomous municipalities, refusing government aid.


SCHREIBER: Olivio Morales is mayor of Monte Flor. He says the community received no notice of the spraying. He believes the Moscamed program is part of a government effort to weaken the Zapatistas by destroying their crops.

MORALES: [SPANISH] They did this with a political motive, because this way they could get the communities to stop resisting. Because when you don’t have anything to eat, well, you have to take the handouts of the government. And the communities here have always refused to take handouts. We have been in resistance, not receiving anything. It was part of a strategy of low-intensity war from the beginning.

SCHREIBER: The Moscamed program is funded largely by the U.S. Some farmers in the area think its goals are economic more than political, part of a plan to destroy their crops so U.S. farmers can take over their markets.

In Monte Flor and another local town, residents are so angry with the program that at one point they detained three of its trucks. The workers were let go but residents held the trucks for several months, demanding that the government compensate them for the damage they blame on the program.

So far, no compensation has been awarded, and Moscamed officials deny the program has any mission other than control of the fruit fly. They admit, though, that their efforts to inform communities of what they are doing have fallen short.


SCHREIBER: The new education sponsored by Moscamed uses videos like this one to explain the program’s goals, methods and accomplishments. There is also a website and pamphlets, keychains, T-shirts, and baseball caps to be given out by brigades sent to work in the affected communities. Part of Moscamed’s strategy is to use non-chemical pest control, but this too has been met with public mistrust. Its airplanes fly low, releasing millions of sterilized fruit flies in paper bags. The idea is that they will mate with the wild flies, which will then fail to reproduce.

Rumors are rampant that the planes are actually releasing rats, snakes, and even spores of coffee rust, a serious coffee plague. To counter the misinformation, the program offers tours of the sterile fly production facility.

FEMALE: [SPANISH] Because the plant houses fertile flies, we have to shower and don lab coats before we can enter.


SHCREIBER: Inside the plant, the smells are intense.

MALE: [SPANISH] The smell is from pheromones. It’s the substance produced by the male to attract the female to copulate. It’s a very strong smell and since here we have a massive number of males, it accumulates and the smell gets even stronger.

   A handful of Mediterranean fruit fly larvae. The Moscamed facility breeds the flies for the sterile insect control program in Chiapas, Mexico. (Photo: Tatiana Schreiber)

SCHREIBER: Each room of the plant houses a different stage in the insect’s life cycle: mating, producing eggs, developing larvae, changing into a pupa, emerging as an adult fly, and starting all over again. At the end of the process, the pupas are irradiated to sterilize them. Then, 500 million a week are released by air over the region’s coffee farms where they emerge as adult flies.

The efforts of the Moscamed program have moved the boundaries of the flies’ territory some 20 miles south of the border into Guatemala. The long-term mission is to eradicate the fly throughout Central America.


SCHREIBER: Ramon Jarquin is a doctoral student in ecology and sustainable development who has worked extensively with farmers in the area. He believes the Moscamed program is necessary to stop the spread of the fruit fly, but he also thinks there should be serious study of the farmers’ complaints. Such a study, he says, would have to include the coffee farmers themselves, because years of Moscamed activities without efforts to involve residents led to the current impasse.

Jarquin says it’s not only a question of ecological damage or health effects. In the political context of Chiapas, Moscamed’s activities are seen as a violation of farmers’ human rights.

JARQUIN: [SPANISH] The airplane represents a violation as far as the right to use the land. People feel their sovereignty has been jeopardized. It’s as if they took the roof off our house and started observing us like puppets.

SCHREIBER: Moscamed officials, though, insist that the complaints about the program are unfounded. They say leaders in the indigenous communities are using the program as a wedge to gain political support. Still, Luis Salmeron Zamora, subdirector of field operations for Moscamed, says the current policy is not to enter communities that don’t support the program.

SALMERON: [SPANISH] First, we ask them permission, and if they don’t give us permission, we don’t do any work.

SCHREIBER: That statement is refuted by farmers who say they haven’t been consulted. But while there is dispute about this, Salmeron says eventually agreements will need to be reached, because a severe outbreak of the medfly would be disastrous.

SAMERON: [SPANISH] If we didn’t fight the medfly here in Chiapas, we’d run the risk that 10 million tons of fruits and vegetables would not be sold, that 4.2 million acres of orchards wouldn’t be cultivated. Annually the value of that lost production, if we didn’t combat the Mediterranean fruit fly, would be $3.5 billion dollars.

SCHREIBER: Salmeron says the program is relying more and more on sterilized flies to attack the medfly problem. They are also breeding a parasitic wasp that kills medflies, and incorporating this technique into their range of eradication strategies. But some farmers here say medfly populations could be kept very low through diligent collection and disposal of affected fruits, and an effort to keep populations of beneficial insects healthy.

But for now, the spraying and insect drops continue. The public relations campaign is in full swing. And residents in several jungle communities still wait for the compensation they say they are due.

For Living on Earth, I'm Tatiana Schreiber in Chiapas.



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