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Adult Mosquito Surveillance

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drawing of trap on wood

Fresno Westside Mosquito Abatement District uses a number of different traps to capture adult mosquitoes for the determination of abundance and the presence of virus activity.  Most traps are placed overnight in set locations throughout the District and collected the next day for identification and sampling.  Samples are sent to UC Davis where they are tested for West Nile virus, and other mosquito-borne encephalitis viruses.  Additional trapping is typically done in response to virus detection, dead birds, and mosquito activity reported by residents.

The primary traps used by the District include:

  1. EVS “CO2” (Attractant: CO2, Targets: Mosquitoes seeking a blood meal)    
  2. Gravid Trap “GT”  (Attractant: Organic Matter-Infused Water, Targets:  Egg-laying Mosquitoes)
  3. Biogents Sentinel Trap “BG” (Attractant:  CO2, and Sweat Analog Chemical Lure,  Targets:  Mosquitoes seeking a blood meal, specialized for invasive Aedes mosquitoes)
  4. Autocidal Gravid Ovitrap “AGO”  (Attractant: Organic Matter-Infused Water, Targets:  Egg-laying Mosquitoes, specialized for invasive Aedes mosquitoes)

Upon collection, mosquito samples are anesthetized, identified to species and sex, and counted under microscope.  Samples of potential disease-carrying mosquitoes are isolated and sent off to University of California, Davis for testing.   Both population totals and the results of virus testing are used to direct future mosquito control operations.


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