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U.S. Researchers Find New Way to Stop Dangerous African Pest
May 9, 2012

By Charlene Porter
IIP Staff Writer
May 8, 2012

U.S. researchers have developed a satellite-guided method of tracking and eradicating tsetse fly populations, action that could prevent disease, save the lives of both humans and livestock, and prevent $4.5 billion in annual losses to African farmers.

The tsetse fly carries Trypanosoma protozoa, which cause a disease commonly known as sleeping sickness in humans and nagana in cattle. Without treatment, the parasite will enter the host’s bloodstream, causing neurological problems, confusion and fatigue. Allowed to go to its extreme, the disease can bring coma, mental derangement and death to humans; its victims are estimated to number in the tens of thousands each year.

The disease follows much the same progression in animals, affecting millions each year. Herds are at risk in 37 countries of sub-Saharan Africa where the fly is found.

Attempting to eradicate the fly through trapping and spraying is expensive, and often ineffective because locating tsetse populations is difficult due to the insect’s living and reproduction habits, climate variables and changing land use.

“As long as you have the right kind of climate for part of the year and a corridor for tsetse to move through, you’ll find it,” says Joseph Messina, a geographer at Michigan State University (MSU), who has been working on better ways to track the tsetse fly since 2007. Messina and his research team tapped into satellite data collected by NASA, which maps vegetation, temperature and land cover every 16 days.

The researchers look at the data like the tsetse would, selecting habitats based on desirable conditions of rainfall, temperature and soil moisture. The MSU team developed a model programmed to identify the most attractive habitats and predict the time when the pests could arrive in those places. This information creates a more effective eradication campaign, Messina says, attacking insects where they are in the present, rather than where they were a few years ago.

“Our model dramatically reduces the cost of controlling the tsetse, and it’s more effective,” Messina said, based on his tests of the model in Kenya compared to historical eradication efforts. The MSU team has published a cost analysis for tsetse control in Kenya in the May issue of Applied Geography.

The tsetse finds its prey through sight and smell, so the researchers lure the tsetse in with a target consisting of an insecticide-soaked cloth colored blue and black and stretched between two poles. The fly mistakes the target for dinner.

“It’s really low-tech,” Messina says, “but it works really well.” Messina’s colleague in the work, Paul McCord, also from the Department of Geography’s Center for Global Change and Earth Observations at Michigan State University, says the targets are also a more environmentally friendly control method than broad spraying campaigns.

In Kenya alone, the cost of eradication efforts using traditional methods based on dated information of tsetse habitat is estimated to be $100 million, according to an MSU press release. The Kenyan government is unable to invest that much in eradication. The proposal developed by the MSU team would cost as little as $14 million because of more strategic targeting of the effort.

Accurately targeting tsetse populations could become increasingly important as climate change brings greater variability to conditions in Kenya. Climate fluctuation will lead the tsetse to new locations in search of its preferred habitat. The MSU team published those findings in Annals of the Association of American Geographers in April.

The U.S. National Institutes of Health and the U.S. Department of Agriculture have funded the MSU research team so far. The next step will be to disseminate the findings and convince officials across the region that there is a better way to identify and eradicate the tsetse fly.