Knowledge of the influence of evolutionary factors that promote either the differentiation or cohesion of pest insect populations is critical for the improvement of control strategies. Here, we explore the extent to which genetic differentiation occurs between populations of the Mexican fruit fly, Anastrepha ludens, in association with four plant hosts (Citrus sinensis, C. paradisi, Mangifera indica and Casimiroa edulis) in the Soconusco region of Chiapas (Mexico). Using variants from six enzymatic loci, we obtained measures of genetic diversity for three sample arrangements: (1) by sex per locality, (2) by locality and (3) by host. The extent of genetic differentiation in populations was assessed using the Analyses of Molecular Variance (AMOVA) method for each array of samples, and moderate to high levels of genetic variation were observed between the sexes, as well as among localities and host plants. A Bayesian approach was then used to assess any population structure underlying the genetic data we obtained, but this analysis showed no significant structuring due to locality or host plant. We also considered whether the observed genotypic frequencies in male and females matched those expected under a hypothesis of random mating. Here we found significant deviations from expected genotypic frequencies, suggesting that sexual selection is acting on these populations. Overall, our results indicate that sexual selection, along with the presence of some heterogeneity in environments provided by both geographical factors and availability of host plants, has influenced the evolution of pest populations in this region of Mexico. Implications for area-wide pest management strategies are discussed.
Genetic Differentiation among Maruca vitrata F. (Lepidoptera: Crambidae) Populations on Cultivated Cowpea and Wild Host Plants: Implications for Insect Resistance Management and Biological Control Strategies
