2011 Annual Report - Sacramento-Yolo Mosquito & Vector Control ...

Mosquito &Vector SurveillanceThe laboratory provides the following technical information to help guide efficient control ofvector-borne diseases in Sacramento and Yolo Counties:• Surveillance of mosquitoes• Encephalitis virus surveillance• Surveillance for other mosquito-borne diseases• Tick and Lyme disease surveillance• Surveillance of bees and wasps• Identification of arthropods of public health significance• Pesticide resistance management• Research and special projectsIn addition to the mosquitospecies found in Sacramentoand Yolo Counties, Districttechnicians are also trainedto recognize any exotic orintroduced species, if present,in any of the thousands ofsamples they collect each year.Surveillance of MosquitoesMosquito surveillance is an essential component of the District’s Integrated Pest Management(IPM) program and a considerable amount of effort is devoted to it. The District’s surveillanceprogram consists of a systematic approach for locating mosquito breeding sources andmonitoring mosquito populations and mosquito-borne disease activity over time and space. Thelaboratory collects and analyzes data on seasonal changes in relative abundances of mosquitospecies, monitors geographic and environmental distribution patterns of mosquito species,determines maximum and minimum risk periods of public exposure to mosquito-borne diseases,and evaluates mosquito control activities. All the data are part of a historical database, whichprovides information on the dynamics of mosquitoes and mosquito-borne disease within theDistrict’s surveillance area.In 2011 our District collected over 169,000 mosquitoes during 3,808 trapping nights in fixedsites throughout Sacramento and Yolo Counties. These were identified to species and countedby our laboratory technicians. The District uses three types of traps for collection of abundancedata — American Light traps, Mosquito Magnet® traps, and Gravid traps. All three trap typesare set in representative sites of different habitats in both counties. These traps are used to gatherinformation on the distribution of all mosquito species and to monitor populations of mosquitospecies of concern. Data are interpreted in the context of historical records and mosquitoabundance is compared to a 5-year average.The American Light trap is the most widely used by mosquito control Districts in California. Itcollects mosquitoes and other insects, which are attracted to the light produced by this trap,regardless of the physiological or behavioral state of the insect. This trap type has been used bythe District for many years and it has provided historical data since before the introduction ofWest Nile virus in our area. The Mosquito Magnet ® trap captures host-seeking mosquitoes thatare attracted to the carbon dioxide emissions that are produced from burning liquid propane.The third type, the Gravid female trap, attracts female mosquitoes that are seeking to lay eggsin water rich in organic materials. The organic water mixture is made of ground alfalfa and hogchow pellets and Brewer’s yeast and is allowed to ferment before being used in the trap.2011 Annual Report7