Theses and Dissertations at Montana State University (MSU)
Permanent URI for this collectionhttps://scholarworks.montana.edu/handle/1/733
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Item Bionomic investigations of Aedes nigromaculis (Ludlow) (Diptera: Culicidae) with special reference to oviposition(Montana State University - Bozeman, College of Agriculture, 1958) Warren, Jack W.Item An ecological risk assessment for mosquito insecticides(Montana State University - Bozeman, College of Agriculture, 2007) Davis, Ryan Scott; Chairperson, Graduate Committee: Robert K. D. Peterson.West Nile Virus (WNV) has been a concern for people across the North America since the disease was observed in the summer of 1999. WNV has caused the largest arboviral encephalitis epidemic in U.S. history. In response, vector management programs have been implemented. Concerns have been raised about these programs My ecological risk assessments focused on six common mosquito adulticides used in vector management, including 3 pyrethroids, pyrethrins, 2 organophosphates, a synergist, and 4 larvicides. Both aquatic and terrestrial non-target organisms were considered for acute and chronic exposures to the adulticides and larvicides. Tier I exposure estimates for adulticides were derived using modeling software. A probabilistic assessment was conducted for the adulticides to account for variability within the exposure models. The larvicide risk assessment included an even settling model into a standard farm pond. Risk quotients (RQ) were obtained by comparing exposure to toxic endpoints. Organophosphates breached a risk quotient (RQ) level of concern (LOC) for amphipods.Item Mosquito populations in the Powder River basin, Wyoming : a comparison of natural, agricultural and effluent coal bed natural gas aquatic habitats(Montana State University - Bozeman, College of Agriculture, 2007) Doherty, Melissa Kuckler; Chairperson, Graduate Committee: Greg Johnson.Coal bed natural gas development in northeastern Wyoming has increased surface water in ranching and agricultural areas over undeveloped land. This increase of water increases larval habitat for mosquitoes, potentially increasing adult populations of West Nile virus vector mosquitoes. I compared adult and larval mosquito populations in four different habitat types in the Powder River basin including agricultural, natural, CBNG and upland sagebrush steppe. Adult mosquitoes were sampled weekly (2004) or bi-weekly (2005) using CDC miniature black-light traps baited with dry ice. A fixed-effect mixed model indicated that in a normal rainfall year (2005) mature CBNG ponds had the highest adult mosquito populations of all sites sampled, and the highest population of the WNV vector Culex tarsalis. In a drought year (2004) where total rainfall from May - August was 59% of the seasonal average, agricultural areas had the highest mosquito abundance, likely due to increased irrigation. Adult Culex tarsalis tested positive for WNV across the PRB in 2004 and 2005, with highest minimum infection rates in those areas with large Culex tarsalis populations.