Mosquito News & Information
Virus May Change Mosquito Control Tactics
In the Midwest, control of the Culex mosquito species has long involved Altosid products, a tactic that may need to be utilized in the East. By Jeff O'Neill.
The recent appearance of the West Nile virus may change the way mosquito control is performed in the eastern United States. There, the Culex mosquitoes that vector the virus historically have not been the targets of operational control, measures because they were considered minor nuisance pests, not important disease transmitters.
In the Midwest, mosquito control agencies have a very different philosophy regarding the Culex species. Culex in that region are potential carriers of endemic St. Louis Encephalitis (SLE) virus and are a major target of control measures. Altosid solid formulations have long been the larvicide of choice for application in Culex habitats in the Midwest.
While stagnant water is present, female Culex mosquitoes lay eggs on a daily basis. When the eggs hatch, newly emerged adult mosquitoes fly away to feed on birds, animals and humans. To prevent the development and spread of the SLE virus, state, county and municipal mosquito control agencies in the Midwest have seasonally treated catch basins, storm sewers, culverts, sewerage lagoons and other standing water habitats.
Stagnant water provides a productive breeding site for Culex mosquitoes.
Altosid® Briquets and Pellets are the products of choice for treating Culex in these habitats. Prior to treatment, these areas are mapped and treated with pellets or briquets. Residual control can last from 30-to-150 wet days, depending on the formulation. In some storm sewers, the water in the sumps never dries out, making them highly productive Culex breeding sites. In these situations, treatment is performed once a month with the 30-day briquet or once per season using the 150-day XR briquet. Research has shown that seven grams per basin of Altosid Pellets provides control of Culex pipiens and Culex restuans for 15 weeks in catch basins.
In addition, if the water in a Culex breeding site dries out, (S)-Methoprene, an insect growth regulator (IGR) present in Altosid, stops being released until the next rainfall event. Once wet, the IGR is released again, for continued prevention of further mosquito emergence. Part of Altosid's success in the Midwest lies in its longevity in the habitat, eliminating the need for the weekly inspections and retreatments that are required with the use of other short-lived larvicides.
Using Altosid saves time and manpower when fighting Culex in the Midwest. Mosquito control professionals in the East may need to adopt similar control tactics to help prevent the further spread of the West Nile virus.