Population Genetics and Gene Variation in Secondary Screwworm (Diptera: Calliphoridae)

Allozyme variation in 4 populations of secondary screwworm, Cochliomyia macellaria (F.), representing North, Central, and South America was examined. Variability was observed in 12 of 13 enzyme loci, and the frequency of the most common allele was <0.95 for 6 loci. Observed and expected heterozygosities were 0.149 and 0.154, respectively. Nei's genetic distances were ≤0.001. Goodness-of-fit statistics for Hardy–Weinberg equilibrium and Wright's FIS statistics indicated random mating within populations. Wright's FST statistics and chi-square contingency analyses indicated homogeneous gene frequencies among the populations. These data suggest that C. macellaria is a panmictic species with high levels of gene flow between populations.