PM14 Pesticides in Pacific Northwest (USA) Watersheds
Exhibit Hall
8:00 AM - Monday

(PM214A) Non-target impacts of B.t.i treatments to control mosquito vectors of west nile virus - implications for aquatic habitats, salmonids and sage grouse in Washington State.

Tamayo, M, Grue, C,

ABSTRACT- Wetlands, particularly those in urban areas, are often the target for mosquito control to reduce the nuisance to surrounding residents. In response to potential loss of human lives associated with the rapid spread of mosquito-borne West Nile virus, local governments are being pressured to control mosquitoes. The bacterial larvicide, Bacillus thuringiensis israelensis (B.t.i.), is commonly used to control mosquito larvae because of its low direct toxicity to vertebrate species. Although vertebrates are not expected to suffer direct adverse effects, there is greater potential for indirect effects from food web disruption. The non-target effects of B.t.i. are poorly understood impeding the development of mosquito control strategies compatible with mandates to enhance and/or protect threatened species and their habitats. In Washington State, efforts to protect human lives may result in losses of invertebrates important to juvenile salmonids (e.g., listed salmon and trout species) for which habitat enhancement activities are underway. The recent listing of sage grouse (Centrocercus urophasianus) likely will further justify the control of mosquitoes within wetlands and moist habitats within its range, as sage grouse are susceptible to the virus. We review the existing information on the non-target effects of B.t.i. and their implications to salmonids and sage grouse in Washington State. Ongoing studies on the non-target effects of B.t.i. on invertebrates important to juvenile salmonids on the Franz Lake NWR will be described as well as efforts to develop an effective research strategy to determine the impacts of B.t.i to salmonids and sage grouse in the State.

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