Determining the susceptibility of the southern house mosquito (Culex quinquefasciatus) to pesticides that target mosquito larvae

Insecticide resistance is a pressing concern for mosquito abatement districts. Louisiana mosquito districts have few records of Culex quinquefasciatus susceptibility to larval insecticides. The southern house mosquito, Cx. quinquefasciatus, is the primary vector of West Nile Virus in Louisiana, and as a result has been the most targeted mosquito species in the region since WNV arrived in the state in 2001. Bacillus sphaericus and methoprene have been used to control mosquitoes in the same habitats of East Baton Rouge for decades, placing these populations under selective pressure. Spinosad is a newly labeled mosquito larvicide, and while its use in Louisiana so far has been limited, larval mosquito spinosad resistance has been well documented in the lab, and has been demonstrated in the field with many other orders of insects. The goal of this thesis is to quantify the susceptibility of East Baton Rouge Cx. quinquefasciatus to three larvicides: Bacillus sphaericus, methoprene, and spinosad. Data obtained will assist local mosquito abatement districts understand the potential for evolution of resistance in local mosquitoes, as well as act as a baseline of susceptibility for future studies in regions where Cx. quinquefasciatus resides.