Date of this Version
Allozyme variation in screwworm, Cochliomyia hominivorax (Coquerel), and secondary screwworm, C. macellaria (F.), populations from northwest Costa Rica was examined . Variability was observed in 11 of 13 enzyme loci and the frequency of the most common allele was <0.95 for 5 loci in screwworm . In secondary screwworm, 12 of 13 loci were variable and the frequency of the most common allele was <0.95 for 6 loci . Expected heterozygosities were 0.149 and 0.160 for screwworm and secondary screwworm, respectively. Goodness-of-fit statistics for Hardy-Weinberg equilibrium and Wrights F statistics indicated that both species are panmictic with no evidence of population substructuring. Nei ' s genetic distances were 0.000–0.001 for intraspecific comparisons and 0.899–0.916 for interspecific comparisons. The data indicate a high level of gene flow between populations within each species.