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

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. Especially if done on a global scale, such research could generate information necessary for the development and application 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 Australasian biogeographical regions. We hypothesized that genetic differentiation would exist across geographical barriers. 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 theAMOVA results. These results suggest that stable flies did not show genetic differentiation but are panmictic, with no evidence of isolation by distance or across geographical barriers

Genetic variability of the stable fly, Stomoxys calcitrans (L.) (Diptera: Muscidae) assessed on a global scale using Amplified Fragment Length Polymorphism

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 \u3e $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. Foste

GENETIC VARIABILITY OF SPINED SOLDIER BUGS (HEMIPTERA: PENTATOMIDAE) SAMPLED FROM DISTINCT FIELD SITES AND LABORATORY COLONIES IN THE UNITED STATES

The spined soldier bug, Podisus maculiventris (Say), is an important biological control agent of agricultural and forest pests; and it preys on eggs and larvae of lepidopteran and coleopteran species. Genetic variability among field samples collected from Michigan, Mississippi, Missouri, Florida and established laboratory colonies was examined using Amplified Fragment Length Polymorphism-Polymerase Chain Reaction (AFLP-PCR). Four AFLP primer pairs generated a total of 340 molecular markers for evaluation. Results from Analysis of Molecular Variance showed that the majority of the genetic variation occurred within populations (individuals from each sample site). Nei’s method indicated reduced genetic diversity in laboratory populations compared to field populations. No major differences or deficiencies were apparent among the field samples from different areas or among the laboratory reared samples. We conclude that field populations are panmictic and laboratory reared spined soldier bug could be useful as biological control agents in the field