West Nile Virus and Reduction of Mosquito Habitats – Part 1

By Marcia Anderson

I have been following the “Worst Outbreak of West Nile Virus (WNV) since 1999” reports in newspapers and on the Internet for days. So far there are 1,118 reported cases and 41 deaths.  Companies have been hired to spray insecticide by plane over Dallas, Texas since August 16. The pyrethroid insecticide selected is said to kill adult mosquitoes by direct contact. In addition, New York City began ground-based spraying on August 24, also to protect people from West Nile Virus. However, spraying is only a temporary answer to the problem, as only adult mosquitoes are killed. Mosquito larvae still reside in bodies of water and will emerge as adults one to five days later.

Why is mosquito control important? About 1 percent of the people that contract WNV usually get either meningitis, an inflammation of the spinal cord, or encephalitis, an inflammation of the brain. People with suppressed immune systems and older people are the most vulnerable to contracting the disease and there is no human vaccine for WNV.

Hungry mosquitoes are attracted to body warmth and exhalation of carbon dioxide. They also find their victims by sight and by chemical sensors. They are especially attuned to ammonia and lactic acid typical in human sweat. The sensors work best in humid air. Only the female mosquitoes require a blood meal which is necessary for making eggs. Did you know that women are bitten more often than men, as women have slightly higher body temperature than men?

What can you do to protect yourself? Follow the 4 Ds:

  1. Use an insect repellant for deterrent.
  2. Dress wearing long sleeves and long pants.
  3. Avoid being in mosquito prone areas around dusk and dawn.
  4. Make sure all standing water is drained.

The fact is that all mosquitoes need water to breed. Many mosquitoes living in urban and suburban settings prefer to breed in standing water rich in decomposing organic material and will not lay eggs in clear water. Dead leaves, grass clippings and algae, quickly begin to break down in moist habitats and produce an infusion that is highly attractive to the females. They are particularly abundant in areas where sewage leaks into drainage systems, catch basins and storm drains. Others will only lay eggs in clean water. The peak time some mosquitoes to bite is just following sunset and just before sunrise, so cover-up or use repellants if you are going to be outside at these times, however, there are some mosquitoes that are 24- hour feeders.

What else can you do? The best  non-chemical mosquito management approach is to reduce/eliminate breeding habitats through the following steps:

1. Identify locations and sizes of all stagnant water bodies, including basins, storm drains, blocked roof gutters, and all water retaining containers. These are all important mosquito larval habitats.

2. Remove or destroy domestic breeding sites. By eliminating all standing water and water collecting containers, you can reduce the number of mosquitoes in your neighborhood. Sites include discarded appliances, car parts, plastic bags, tarps, food containers, tires, pet water bowls left out for days,  saucers, potted plants, and birdbaths, kiddy pools, children’s play equipment left outside to collect water, and garbage cans and dumpsters without proper drainage or lids.

If you live in an area with swales, open stormwater culverts or trenches, they need to be maintained to prevent them from becoming filled with sediment and plant debris. This will cause ponding or puddles of water that may soon become a mosquito breeding habitat. Clogged gutters and flat roof tops with poor drainage are commonly overlooked mosquito breeding habitats.  Thus, if there is standing water close to you, that you cannot do anything about, please call 311 in New York City.

About the Author: Marcia is the bed bug and vector management specialist for the Pesticides Program in Edison. She has a BS in Biology from Monmouth, second degree in Environmental Design-Landscape Architecture from Rutgers, Masters in Instruction and Curriculum from Kean, and is a PhD in Environmental Management candidate from Montclair – specializing in Integrated Pest Management and Environmental Communications. Prior to EPA, and concurrently, she has been a professor of Earth and Environmental Studies, Geology and Oceanography at Kean University for 14 years.

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