Q: How does the Carson City mosquito abatement program work?
A: Since the early 1990s, Carson City Health and Human Services has performed mosquito abatement each summer to protect the community from this public health nuisance.
Much to the alarm of many residents, recent city-wide budget cuts threatened the program. However, new funding sources were identified, and the Carson Water Subconservancy District and Carson City Public Works will keep the program active. As in years past, helicopter and ground treatments will take place throughout the 2010 mosquito season.
Mosquitoes are notorious for their dark side - biting people and spreading disease including West Nile Virus. The Centers for Disease Control and Prevention reported 12 human cases of West Nile in Nevada in 2009.
Throughout the warm months, a Carson City Environmental Health Specialist will conduct a weekly assessment to determine where and how bad our mosquito problem is. Assessments involve daily surveillance of standing water for mosquito larvae. Complaints made to the Health Department about mosquitoes are archived and this information is factored in as well.
"We do not treat unless we find larvae or adult mosquitoes," said Teresa Hayes, the Carson City mosquito abatement coordinator. "Our approach is spot-specific." Teresa, who is an ecologist and evolutionary biologist, explained that overdoing mosquito control could upset the ecosystem.
On occasion, mosquito traps are set. These hanging traps have lights and dry ice in them to attract the mosquitoes. Evaporating dry ice emits Co2, which mosquitoes interpret as human exhaled breath. The mosquitoes are trapped live, frozen, and tested at the Washoe County Vector Control lab for West Nile.
If the virus is found in any of the mosquitoes, abatement activity is enhanced.
About 90 percent of Carson City's mosquitoes reside along the Carson River corridor, and the remaining 10 percent are scattered around town. There are a few naturally occurring ponds in Carson City that never require abatement because they have a healthy population of Gambusia (mosquito-eating) fish.
River areas are treated from a helicopter, and the in-town abatement is done on foot. The product used to control the mosquitoes in both cases is a safe, dry insect growth regulator called (S)-Methoprene. Methoprene does not kill mosquitoes; nor, if used properly, does it affect fish, waterfowl, mammals or beneficial predatory insects. It works by interrupting the growth cycle of mosquito larvae by keeping them immature and thus incapable of biting or breeding.
• Pam Graber is public information officer for the Carson City Health and Human Services department. Contact her at pgraber@ci.carson-city.nv.us.