04:30pm Friday 20 October 2017

Dangerous mosquitoes flourish in fall’s drier climate, says ISU entomologist

Lyric Bartholomay, assistant professor of entomology, works with a light trap that is used to capture mosquitoes to be tested for virus infection. The trap uses light and carbon dioxide to lure in mosquitoes, and sucks them into the net with a fan.

ISU photo by Bob Elbert

Lyric Bartholomay, assistant professor of entomology, is in charge of monitoring mosquito populations and mosquito-borne diseases around the state. She spreads the word about mosquito numbers through an online database that goes back more than 30 years and tracks the number and types of the bugs that are so common in Iowa.

She says that protecting yourself during 4th of July outings and pool parties in the hotter months of summer is important, but there is a very real danger now.

“The second case of West Nile virus in Iowa this year was reported last week,” said Bartholomay. “Sometimes the disease is sort of forgotten about, but it is still newsworthy and it makes people very sick.”

The reason September and the first weeks of October are important, she says, is because that’s when the types of mosquitoes that carry the more dangerous viruses are breeding and looking for food.

“If you think about a normal Iowa year, in midsummer, it’s hot and humid and wet. The types of mosquitoes that are on you when you’re out mowing the lawn then, are pesky and horrible,” said Bartholomay. “But these more abundant types of midsummer mosquitoes are not usually the ones that carry the more dangerous disease pathogens.”

“Mosquitoes that transmit West Nile virus are the ones that mostly lay their eggs in the filthy, stagnant water that is more common when the weather turns drier, like now in the fall.”

These more dangerous, late-season mosquitoes often feed on birds that have West Nile virus through the summer. When the birds start their annual migration south for the winter, the mosquitoes look for other sources of blood – often people – transferring the pathogen to the new food source.

West Nile virus is spread by mosquitoes and can cause serious, life-altering diseases and even death, according to the Centers for Disease Control and Prevention web site.

Bartholomay and her staff work with health officials from around the state who collect mosquitoes and send up to several “hundreds of thousands” of mosquitoes each year to Iowa State University, depending on weather conditions and populations sizes.

Once in the lab, the staff catalogues the number, type and place of origin for each mosquito.

The findings are on the web site iowamosquito.net.

This program is funded by the Iowa Department of Public Health.

Bartholomay says that keeping track of the summertime pests is important for public health in the state.

“This is a valuable public resource and is tremendously important,” said Bartholomay. “For instance, when the West Nile virus spread across the United States, we had current information on the number of mosquitoes, what kind of mosquitoes and where the mosquito populations were changing. We were way ahead of other states that had no information on their mosquito populations.”

Bartholomay is also monitoring new, invasive species of mosquitoes that may become a public health problem for Iowans in the future.

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Contacts:

Lyric Bartholomay, Entomology, (515) 294-0594, lyricb@iastate.edu


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