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Use IPM to Combat West Nile Virus - June 2005

June, 2005

UNIVERSITY PARK, Pa. -- Ordinarily, mosquitoes are little more than a mild irritant, but because they can transmit diseases such as West Nile encephalitis to humans and pets, people should take steps to avoid being bitten and eliminate mosquito-breeding areas.

In 1999, 62 people in the New York City metropolitan area were hospitalized with West Nile encephalitis, previously only found in Africa, Eastern Europe, Middle East, and West Asia. Seven of those people, all elderly, died. In response, the Pennsylvania Departments of Health and Environmental Protection, in cooperation with other state and local agencies, finalized plans to monitor the Commonwealth for potential mosquito and bird carriers of the virus that causes West Nile encephalitis.

West Nile encephalitis cases occur primarily in the late summer or early fall. Mosquitoes get the virus when they bite, or take a blood meal, from birds infected with West Nile virus. Those mosquitoes then transmit the virus to people and other animals when taking a blood meal. Over the last several years, dead birds in Pennsylvania, New Jersey, New York, Connecticut, and Maryland have tested positive for the virus.

During warm weather, mosquitoes can breed in any still water that stands for more than four days. The most effective way to control mosquitoes is to eliminate standing water. Homeowners should use IPM, or integrated pest management, tactics to protect themselves and their families. IPM aims to manage pests -- such as insects, diseases, weeds and animals -- by combining physical, biological and chemical tactics that are safe and environmentally compatible. Homeowners should follow these IPM tips:
-Remove old tires, tin cans, buckets, glass jars, toys and other water-catching objects
-Tightly cover rain barrels to prevent egg-laying
-Try using Bti, a naturally occurring bacteria, to kill mosquito larvae in standing water. Bti can be purchased in small, donut-shaped form, often called "mosquito dunks", which are useful in small areas of standing water, such as a birdbath or small puddle of water. Granular Bti is also available, and effective for larger areas, such as backyard ponds.
-Change water in bird baths by flushing with a hose at least once a week
-Fill tree holes with sand or cement or drill holes to allow drainage
-Keep rain gutters clean and free of obstructions
-Drain excess water from flower pots
-Keep swimming pools covered when not in use
-Turn over wading pools and wheelbarrows when not in use
-Empty accumulated water from boats and cargo trailers
-Clear aquatic vegetation from around the edges of ponds to allow fish to feed on mosquito larvae and pupae

Mosquitoes should be excluded from buildings by keeping windows, doors and porches tightly screened. For mosquitoes inside the house, use a fly swatter.
When outside, wear long-sleeved shirts and long trousers. Avoid peak mosquito feeding times, usually dusk to dawn. When going outdoors for an extended period of time, insect repellents can provide protection from mosquito bites. Repellents can protect for up to five hours, but because people vary in their attractiveness to mosquitoes, the effectiveness of the repellent may depend on the individual. Before using a repellent or insecticide, be sure you thoroughly read and understand all directions and cautions on the product label.

Organize your community to clean up mosquito breeding areas. Neighborhood clean up days can be organized through civic or youth organizations. Homeowners can be encouraged to clean up their yards, and water collecting containers can be picked up from vacant lots.

For more information on West Nile encephalitis, visit Pennsylvania's West Nile Virus Surveillance program at Web site http://www.westnile.state.pa.us/. You may also visit Penn State's College of Agricultural Science's Web site on West Nile encephalitis at http://www.pested.psu.edu/issues/wnv/.

The Pennsylvania IPM program is a collaboration between the Pennsylvania State University and the Pennsylvania Department of Agriculture aimed at promoting integrated pest management in both agricultural and nonagricultural situations. For more information, contact the program at (814) 865-2839, or visit Web site http://paipm.cas.psu.edu. To view our archived news releases, see Web site http://paipm.cas.psu.edu/newsrelease.html.