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United States Department of Agriculture

Agricultural Research Service

Research Project: HIGHER DIPTERA PESTS OF LIVESTOCK AND POULTRY: SCREWWORM FLIES

Location: Screwworm Research

Title: Amplified Fragment Length Polymorphism Used to Investigate Genetic Variability of the Stable Fly (Diptera: Muscidae) Across North America

Authors
item Kneeland, Kathleen -
item Skoda, Steven
item Foster, John -

Submitted to: Journal of Medical Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 28, 2013
Publication Date: September 1, 2013
Citation: Kneeland, K.M., Skoda, S.R., Foster, J.E. 2013. Amplified Fragment Length Polymorphism used to investigate genetic variability of the stable fly (Diptera: Muscidae) across North America. Journal of Medical Entomology. 50(5):1025-1030.

Interpretive Summary: Stable flies are important pests of livestock and humans the world over. Their painful bite causes extreme irritation and stress. They are estimated to cause more than $2 billion in annual losses to the cattle industry in the U.S. alone. Understanding the population genetics of stable flies could provide information on their population dynamics, origins of outbreaks, and geographical patterns of insecticide resistance, resulting in a tactical advantage for developing management strategies. Previous studies, mostly on a local scale, reported a high level of gene flow between locations. Here we used amplified fragment length polymorphism to determine genetic diversity of stable fly samples consisting of 11-40 individuals from 12 locations in the United States, Canada, and Panama. Results showed that the majority of genetic diversity was within groups. Insignificant genetic diversity was observed among groups. Estimates of genetic differentiation were moderate while estimates of migration were high. The tests suggested that stable flies are experiencing population expansion, no genetic differentiation was found between locations, and there is a high level of gene flow on a continental scale with little isolation by distance or across geographical barriers. Therefore, effective control strategies in one region should be equally effective in another region. Also, stable fly resistance to a control method in one region would be expected to spread quickly to other regions. This is valuable information relative to the control of this important pest.

Technical Abstract: The stable fly, Stomoxys calcitrans (L), is a cosmopolitan pest of livestock and humans; its pestiferous nature and painful bite cause stress to cattle and other animals. The stress and resulting avoidance behaviors manifest as reductions in weight gain or milk production in cattle; estimated annual economic loss in the United States exceeds $2 billion. Investigations on the population genetics of stable flies provide information on their population dynamics, origins of outbreaks, and geographical patterns of insecticide resistance, which provides a tactical advantage for developing management strategies. Previous studies, mostly on a local scale, reported a high level of gene flow between locations. Here we report results wherein amplified fragment length polymorphism was used to determine genetic diversity of stable fly samples consisting of 11-40 individuals from 12 locations in the United States, Canada, and Panama. AMOVA showed that the majority of genetic diversity was within groups. Insignificant genetic diversity was observed among groups. The FST and GST values were low; Nm values very high. The tests of neutrality suggested population expansion and no genetic differentiation were found between locations. These results show that stable flies have a high level of gene flow on a continental scale, with no isolation by distance or across geographical barriers.

Last Modified: 9/1/2014