Surveillance

 

Mosquito surveillance is an ongoing process by which the District determines the overall population density as well as the species composition within that population. The guiding force for all control operations in any IMM program is based upon the data obtained through regular surveillance.

Larval surveillance is performed through the inspection of water-holding areas and containers. Frequently, a dipper is used to sample the water for the presence of larvae.

For the collection of adult mosquitoes, Tangipahoa Mosquito Abatement uses various traps and techniques to capture different species to be identified and counted. This aids in providing optimal control methods for the most affected areas.

CDC Traps
  • Based on a CDC (Centers for Disease Control) designed CO2 (Carbon Dioxide) trap.
  • Battery-powered and portable.
  • Typically attracts more aggressive, nuisance mosquitoes.

How it works:

A one-gallon cooler is filled with dry ice, and a battery-powered light and fan hang beneath the trap. As this dry ice sublimes, CO2 is released, which serves as an attractant for mosquitoes. As they approach, they are sucked into a net. The net is collected the following day and the mosquitoes are identified by species and counted.

CDC Trap
Figure 1: CDC Trap.


Gravid Traps
  • Battery-powered, portable.
  • Consists of a tube containing a fan that is placed over a bucket.
  • Bait is fish emulsion.
  • Attracts mosquitoes that mainly breed in septic ditches (Culex quinquefasciatus-The Southern House mosquito).

How it works:

The trap attracts female mosquitoes that have typically had a blood meal and are gravid (egg bearing). These mosquitoes are looking for a place to lay eggs, and are attracted by the fish emulsion. As they fly over the bait, they are sucked into a net by the fan. The net is collected the following day and mosquitoes are identified and counted.

Gravid Trap
Figure 2: Gravid Trap.


Landing Rate Count
  • Inspectors use themselves as “bait.”
  • Record number and species of adults landing in a given period of time (usually one minute).
  • May also count mosquitoes approaching, but not landing.
  • Though different mosquito species may be active at different times of the day, our inspectors can disturb these mosquitoes and note populated areas.
  • This information is used along with other factors to determine the most effective control strategy.


Disease Testing
  • Adult female mosquitoes from traps are pooled into samples of 5-100 and sent to the Louisiana Veterinary Medical Diagnostic Laboratory.
    • Tested for the presence of West Nile Virus, St. Louis Encephalitis (SLE), and Eastern Equine Encephalitis (EEE) antibodies
  • Data collected from traps are also used to determine if an outbreak in specific mosquito species has occurred.