Tips to help control mosquitoes

Summertime is quickly approaching. With it will come one of summer's most familiar pests — mosquitoes. And with mosquitoes comes the threat of West Nile virus.

James Kennedy, professor of biological sciences and an aquatic entomologist, and biology graduate student Bethany Bolling are experts on the spread of the virus, which garnered national attention last summer as it spread across the South and Southwest.

Since last April, Kennedy and Bolling have been monitoring mosquito populations in the Texas Parks and Wildlife Greenbelt corridor, which runs north and south along the Elm Fork of the Trinity River, near Aubrey, Denton, Pilot Point and Little Elm.

Kennedy suggests a two-pronged approach to reducing the mosquito population and diminishing the threat of disease — control and prevention.

According to the Centers for Disease Control and Prevention, the insect repellant DEET is an effective mosquito deterrent, but users should check the CDC web site, www.cdc.gov, for insect repellant use and safety instructions.

"Even though chemically based pesticides are effective and have become less hazardous over the years, I recommend environmentally friendly control methods," says Kennedy. "These techniques are less likely to cause human health problems. For example, environmentally friendly biocides like Bacillus thuringiensis, a naturally occurring bacteria, can be applied to habitats where mosquito larvae live."

Control methods such as spraying at night with pesticides must be scrutinized for safety and should not be applied routinely, he says. Some of the mosquitoes will die, but bugs that are predators of the mosquitoes will also perish.

Kennedy suggests many other ways people can help protect themselves from the threat of mosquitoes.

"If you can control the water they breed in, you can control their population," he says. "If you see something wiggling in standing water, it's likely that it's the larvae of a mosquito. If you see it tumbling, that's probably a pupae, which is a more advanced state of mosquito development."

Kennedy encourages people to prevent mosquito infestation by removing any standing water from places like household drainage pipes, buckets and birdbaths. Getting rid of leaves in gutters that hold water and removing tires that also tend to hold standing water will also help control the population.

He also recommends introducing the Gambusia affinis — commonly called the mosquito fish – to any standing water. These fish are top feeders that will kill the mosquitoes.

Besides these methods of prevention, the CDC encourages people to dress appropriately – in long sleeves and long pants — when going outdoors, particularly during dusk and dawn when exposure is heightened.

The CDC also recommends checking with an organized mosquito control program in your area or working with your local government to establish such a program.

"All Texas citizens should be vigilant and aware that mosquitoes are adaptable," says Kennedy.

Bolling says the peak time for contact with mosquitoes is August and September, but the mosquito breeding season starts much sooner. Texas towns with flooding problems will have a higher risk for exposure to infected mosquitoes, she says.

"Mosquitoes pass the West Nile virus from one living thing to another," Kennedy says. "The virus is passed from a mosquito to a bird during what's called a ‘blood meal.'"

Kennedy says once a bird becomes a carrier, the virus could exist inside the bird without harming it. When a virus-free mosquito bites an infected bird, it too becomes a West Nile carrier.

"Mosquitoes and birds are carriers of some viruses, but not others," he says. "They carry West Nile and other brain-swelling, encephalitis-type viruses, along with viruses like Dengue and Yellow Fever, but they don't carry viruses like HIV."

The West Nile virus ultimately gets into the saliva of the insect and is injected during feeding. Typically, this cycle goes back and forth between bird and mosquito, but mammals — including human beings — can also be bitten and infected.

Kennedy says when a mosquito with the West Nile virus bites a healthy person, it normally causes nothing more than flu-like symptoms. However, people most at risk of a serious reaction are children and the elderly, he says. A potential risk for brain swelling and death exists in these populations.

Finally, Kennedy says, a rational reaction to the West Nile virus is the best line of defense. With a little preparation, summertime can be a time of easy living and less swatting.

BY CATHY CASHIO ccashio@unt.edu

Other featured articles in this issue

• Regents approve senior vice president appointment
• Medical geographer researches spread of infectious diseases like SARS
• UNT parking permits for 2003-04 now for sale through intercampus mail
• Two UNT programs ranked high this year by U.S. News and World Report
• Elm Fork Education Center to conduct summer camps
• Staff Council holds its final meeting of the 2002-03 academic year
• Staff awards presented at President's Staff Sack Lunch

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