University Of Florida Scientists Say Global Warming Could Spread Mosquito

"Our research shows that, like many mosquitoes, this species breeds faster as the temperature gets higher," said Barry Alto, a University of Florida entomology doctoral student and co-author of the study appearing today in the Journal of Medical Entomology. "If global warming trends continue, the Asian tiger mosquito may become common in places it's not found today.

What’s more, he said, the Asian tiger mosquito may be just the beginning.

"Some research indicates that global climate change may alter the current distributions of other mosquito species," Alto said.

Native to East Asia, the Asian tiger mosquito has spread widely in the last two decades, transported in shipments of used automobile tires containing its eggs, Alto said. Warmer regions of North and South America, Europe and Africa now harbor the species, known scientifically as Aedes albopictus. It was first reported in the United States in 1985 and has reached at least 25 states, mainly in the East and South.

"This mosquito spread quickly in the South," Alto said, "whereas in the Midwest, it's less common although it arrived in the mid-‘80s.”

The Asian tiger mosquito is named for its appearance, black with silver-white bands. Though small, the species is an aggressive biter, attacking humans, livestock and wildlife, mainly during daylight hours.

Phil Lounibos, a UF entomology professor who studies the Asian tiger mosquito, said it draws interest from researchers worldwide.

"So many places are affected by this insect," Lounibos said. "It would be just a nuisance except that it can transmit serious viral diseases." In the tropics, the mosquito carries dengue fever, which infects tens of millions but is usually not fatal. A severe, hemorrhagic form of the disease infects hundreds of thousands each year and kills about 5 percent of those infected.

"Dengue is epidemic in northern and southeastern Brazil right now," Lounibos said. "We're trying to stop it. Competition between the Asian tiger mosquito and the yellow fever mosquito, another invasive species that transmits dengue, may play a role in the crisis."

Alto said the study compares reproduction of Asian tiger mosquitoes housed at 79, 75 or 72 degrees Fahrenheit. Mosquitoes kept at 79 degrees reproduced fastest, while those at 72 degrees reproduced slowest.

"The difference between the low and high temperatures -- 7 degrees -- matches some estimates of how much global temperatures will increase in the next 100 years," he said.

The study shows that higher temperatures, when considered alone, would probably allow the mosquito to spread farther north and possibly survive year-round in areas where winter freezes now kill it off, he said.

Steven Juliano, an Illinois State University biological sciences professor and co-author of the study, said global warming also is predicted to affect rainfall and humidity, so the study does not make definite predictions about the mosquito's possible spread. Still, he said, it provides some valuable insight.

"Insect population dynamics are affected by many variables," Juliano said. "But this study helps us highlight what we need to know to plan for the future."

Juliano and Alto are conducting follow-up research at the Florida Medical Entomology Laboratory in Vero Beach as part of a project concerning invasion biology of the Asian tiger mosquito. Juliano said the project is funded by the National Institutes of Health and involves researchers from UF's Institute of Food and Agricultural Sciences, Illinois State University, Yale University and Brazil's ministry of health.