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The stable fly, Stomoxys calcitrans, is a cosmopolitan pest of livestock and humans. It is a major pest in livestock facilities, where exist excellent breeding sites such as spilled feed mixed with manure. The pestiferous nature and painful bite cause stress to cattle and other animals. Cattle perform avoidance behaviors such as bunching together, standing in water, tail swishing, ear flicking and leg stamping. The stress and avoidance behaviors result in reductions in weight gain or milk production, with an estimated annual economic loss of > $1billion. Therefore, the development of more efficient control methods would benefit the global economy, as well as the animals.
Studying the population genetics of stable flies could provide information on their population dynamics, origins of outbreaks, and geographical patterns of insecticide resistance. Many studies have been conducted on a local scale, most reporting a high level of gene flow between locations. To date, few studies have been conducted on a global scale. Here I report a study of samples acquired from
4 biogeographical regions: Nearctic, Neotropical, Palearctic and Australian. No samples were acquired from the Oriental region.
The results indicate a high level of gene flow on a global scale. FST and GST values are low, and Nm values very high. The tests of neutrality suggest population expansion, and tests for genetic differentiation simply reported “no differentiation”. AMOVA results show the majority of genetic diversity is within groups, and very little among groups. These results suggest that stable flies have a panmictic population, with no isolation by distance or across geographical barriers.
Advisors: Steven R. Skoda and John E. Foster