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Mosquito species may spread because of global warming
( 2001-07-06 11:35 ) (7 )

One of the effects of global warming could be the spread of the disease-carrying Asian tiger mosquito, a new study warns.

Two researchers at Illinois State University found that the Asian tiger breeds faster in higher temperatures.

That means the mosquito, along with other species, could spread farther north and survive year-round in climates where colder winter temperatures now kill them off, they said.

Named for its white-striped legs, the tiger mosquito is a vicious biter that transmits tropical viruses including dengue fever, yellow fever and forms of encephalitis.

It arrived in the United States in 1985 in a shipment of used tires brought into Jacksonville, Florida, and is found in 25 states in the Northeast, Midwest and South. It has also spread to Europe, Africa and South America.

``If global warming trends continue, the Asian tiger mosquito may become common in places it's not found today,'' said Barry Alto, co-author of the study appearing Thursday in the Journal of Medical Entomology.

However, the research makes no definite predictions because it doesn't consider the effect of other climate changes, such as humidity and rainfall, on breeding.

Alto, a University of Florida entomology doctoral student, and the study's co-author Steven Juliano, an Illinois State University biological sciences professor, are doing follow-up research at the Florida Medical Entomology Laboratory in Vero Beach.

Richard Merritt, a Michigan State University entomology professor, said the study was a good first step in determining the potentially dangerous correlation between global warming and insect breeding. He said higher mosquito concentrations increase the chance that a virus they carry could spread to humans.

``If they're able to make it without dying or freezing, then this is definite reason for concern,'' Merritt said.

Alto and Juliano compared reproduction rates for the tiger mosquito at 79, 75 and 72 degrees Fahrenheit (26, 24 and 22 degrees Celsius). They found that the mosquito reproduced the fastest when housed in the highest temperature.

Those five degrees (four degrees Celsius) are within the range of the estimates of how much the Earth's temperature will rise over the next century from global warming.

Many blame the phenomenon on heat-trapping greenhouse gases in the atmosphere resulting from the burning of fossil fuels and other human activities.