Demographic and Historical Processes Influencing Cochliomyia hominivorax (Diptera: Calliphoridae) Population Structure across South America
BackgroundThis study investigates the genetic variability and population structure of Cochliomyia hominivorax, the New World screwworm fly. This study tested the hypothesis that the species exhibits a center-periphery distribution of genetic variability, with higher genetic diversity in central populations (e.g., Brazil) and lower diversity in peripheral populations. MethodsUtilizing microsatellite markers, we analyzed larvae collected from infested livestock across South America. Larvae were collected directly from various wound sites to ensure a broad representation of genetic diversity. ResultsContrary to our initial hypothesis, the results revealed consistent genetic variability across the species distribution, low population differentiation, and no evidence of isolation-by-distance patterns among subpopulations. The genetic analysis indicated an excess of homozygotes, potentially due to the Wahlund effect, null alleles, or selection pressure. ConclusionsThese findings suggest a complex metapopulation structure for Co. hominivorax, challenging classical population genetics models. This complexity likely arises from the species high dispersal capability and frequent local extinctions followed by recolonization. These results have important implications for the design and implementation of control programs, emphasizing the need for coordinated and large-scale actions rather than isolated initiatives.