Mosquito Control Commission

SURVEILLANCE

During the mosquito-breeding season, surveillance programs are necessary so that control activities can be concentrated in those areas with the most serious problems. Several surveillance techniques are used:

• New Jersey light trap surveillance
• CDC traps surveillance
• Omni Faye-Prince Traps
• Gravid Traps
• Sentinel Flocks
• Larval dipping surveys
• Citizen Participation (service requests)

Mosquito light traps (New Jersey light traps)
Use a 25W bulb, are placed throughout the City of Chesapeake to attract and capture adult mosquitoes for identification of species. Since different species prefer different habitats in which to breed, it is important to know which species are causing problems so that breeding sites can be found and treated or eliminated.

CDC (Center for Disease Control) traps
Our participation in the Tidewater Regional Arboviral Surveillance Program helps us detect the presence of Eastern Equine Encephalitis (EEE) and West Nile Virus (WNV). We catch mosquitoes with CO2 baited CDC traps, sort according to species, and pool the species capable of viral transmission. We then send the pools to the Norfolk Department of Public Health Lab for testing. We also submit serum samples from sentinel chicken flocks to test for each virus.

Omni Faye-Prince Trap
The Omni-Directional Fay-Prince Trap, is a daytime trap which is quite specific for Aedes albopictus adults of both sexes; it will capture gravid and nuliparous females.

Gravid Trap
The advantage of using gravid traps is that they almost exclusively collect mosquito species that are capable of transmitting diseases (i.e. Culex spp., Anopheles, etc.). Furthermore, they almost exclusively collect females of these species that are ready to lay eggs in the stagnant, vegetation enriched water that these mosquitoes like to develop in. Coincidently, if one of these mosquitoes is ready to lay their egg then that means that it had to have fed on a host (i.e. birds) for a blood meal. If by chance one of those hosts were infected with WNV/SLE then it will produce a positive VecTest sample.

Sentinel flocks (chickens)
The sentinel flocks are located in various areas of the city. The chickens are well taken care of. The chickens are used to monitor disease in the area. The chickens have blood drawn every two weeks to test for WNV and EEE.

Larval dipping surveys
Larval dipping surveys important tool in mosquito control surveillance programs. Mosquito larvae are found in many different types of aquatic habitats, from tree holes to salt marshes. While not a direct measure of the number of biting adult mosquitoes, dipping surveys do show where mosquitoes are breeding, and are very important in Larviciding efforts. Since the emergence of Aedes albopictus, a container breeding mosquito that is often found near homes, citizen participation (service requests) has been a very important and reliable tool in surveillance techniques.