Analysis of the genetic structure of a natural population of Anastrepha fraterculus (Diptera: Tephritidae)

The South American fruit fly Anastrepha fraterculus (Wiedemann) is distributed from Mexico to northern and central Argentina. It is a polyphagous species using diverse fruit from wild and cultivated tree or shrub species as feeding and breeding sites. During larval stages, the environment is discontinuous, because the larvae are restricted to the fruit where their eggs were laid. This population structure should profoundly influence the distribution of genetic variation and the modes of action of adaptive mechanisms. During the adult stage, in contrast, the population is not structured. In the current work we analyze the genetic structure in an Argentine population (Yuto) among attacked fruits at 4 enzyme loci. The results differed from the expected for a random mating population in the genotypic frequency distribution, the effective inbreeding coefficients, and the correlation between allelic and nonallelic valiant frequencies. The most plausible explanation is that populations of this species may include heterogeneous groups of individuals having different origins as the species undergoes host shifts throughout the year.