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Title: Genetic variability of the stable fly assessed on a global scale using amplified fragment length polymorphism

Author
item KNEELAND, KATHLEEN - University Of Nebraska
item Skoda, Steven
item FOSTER, JOHN - University Of Nebraska

Submitted to: Insect Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/4/2015
Publication Date: 5/1/2015
Publication URL: http://handle.nal.usda.gov/10113/62266
Citation: Kneeland, K.M., Skoda, S.R., Foster, J.E. 2015. Genetic variability of the stable fly assessed on a global scale using amplified fragment length polymorphism. Insect Science. 00:1-9.

Interpretive Summary: Stable flies are important pests of livestock and humans the world over. Their painful bite causes extreme irritation and stress resulting in 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 that could result in a tactical advantage for developing management strategies. Previous studies, mostly on a local scale, reported a high level of gene flow between locations. We used molecular markers generated from the technique amplified fragment length polymorphism to determine genetic diversity of stable fly samples consisting of 10-40 individuals originating from 25 locations in North America, Central America, Europe, Africa and Australia. Results showed that the majority of genetic diversity was within groups; very little was 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 (fly population 'mixing') on a global 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 control of this important pest.

Technical Abstract: The stable fly, Stomoxys calcitrans (L) (Diptera: Muscidae), is a blood-feeding, economically important pest of animals and humans worldwide. Improved management strategies are essential and their development would benefit from studies on genetic diversity of stable flies. Such research, especially if done on a global scale, could generate information necessary for the development of more efficient control methods. Herein we report on a genetic study of stable flies using amplified fragment length polymorphism, with samples of 10-40 individuals acquired from a total of 25 locations in the Nearctic, Neotropic, Palearctic, Afrotropic and Australian biogeographical regions. Although FST (0.33) was moderately high, the GST (0.05; representing genetic diversity between individuals) was very low; Nm values (representing gene flow) were high (9.36). The mismatch distribution and tests of neutrality suggested population expansion, with no genetic differentiation between locations. The Analysis of Molecular Variance (AMOVA) results showed the majority of genetic diversity was within groups. The mantel test showed no correlation between geographic and genetic distance; this strongly supports the AMOVA results. These results suggest that stable flies are panmictic, with no evidence of isolation by distance or across geographical barriers.