Sky eyes spy mosquitoes.

Sky eyes spy mosquitoes

Using aircraft and space-based sensors, researchers correctly predicted an influx of malarial mosquitoes into California rice fields months before the insect population peaked, suggesting the technique may prove valuable in countries threatened by the disease.

The malaria-causing microbe doesn't live in California, but the state harbors populations of Anopheles freeborni, a mosquito that can carry the parasite. Working at NASA's Ames Research Center in Mountain View, Calif., Byron L. Wood, Kathy A. Hibbard and colleagues used orbiting satellites and remote-sensor-equipped aircraft flying at 30,000 feet to measure near-infrared and red wavelengths reflected from 104 rice fields in Sutter County.

The team found that the ratio of these two wavelengths provides a "spectral signature" that accurately measures subtle changes in vegetation patterns. To correlate these changes with mosquito populations, they compared the spectral data with weekly counts of mosquito larvae, hand-gathered by Robert K. Washino and others from the University of California, Davis. They then added information from digitized land-use maps showing the proximity of cattle -- the major food source of mature A. freeborni. Combining all these details, they created a mathematical model that predicts mosquito movements two months in advance with 77 to 85 percent accuracy, depending on time of year. "That's pretty good," Hibbard says, "considering you can't see mosquitoes from space."

She adds that the team has begun adapting the technique for use in Mexico, where the problem is "exponentially more complex" because two species of malaria mosquitoes live there in very different habitats. In the long run, however, the method could enable public health officials to control infestations before they grow too large, Hibbard said this week at the Ecological Society of America's annual meeting in Snowbird, Utah.