Genetic and Ecological Relationships of Anastrepha ludens (Diptera: Tephritidae) Populations in Southern Mexico

Abstract

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.

Mass-Rearing Conditions Do Not Always Reduce Genetic Diversity: The Case of the Mexican Fruit Fly, Anastrepha ludens (Diptera: Tephritidae)

“…All three samples also showed high levels of homozygosity, suggesting high levels of inbreeding. This may be unique to A. ludens because previous studies with wild populations reported that A. ludens showed high values of F-fixation [47][48][49], possibly reflecting limited dispersal of these populations and the tendency of this species to mate with related individuals, even in the field. Genetic drift may also be a relevant factor for the high levels of homozygosity since most of the samples used here were not in Hardy-Weinberg equilibrium.…”

Coping with global warming: Adult thermal thresholds in four pestiferous Anastrepha species determined under experimental laboratory conditions and development/survival times of immatures and adults under natural field conditions

“…The four species are distributed in the tropical zones of Mexico where temperatures tend to be warm, but in the case of A. ludens it has been recently expanding its distribution range invading high altitude, temperate areas where apples ( Malus × domestica Borkh.) and pears ( Pyrus communis L.) are grown (M. Aluja personal observations; Ruiz-Montoya et al, 2020 ). We note that these species belong to two different species groups which render our study more robust and interesting.…”

Nuclear genetic diversity and structure of Anastrepha ludens wild populations evidenced by microsatellite markers

“…Molecular analyses based on population genetics studies on A. ludens using mitochondrial sequence polymorphisms (Ruiz-Arce et al, 2015), biochemical markers such as isoenzymes and molecular dominant amplified fragment length polymorphism (AFLP) markers (Malavasi and Morgante, 1982;Molina-Nery et al, 2014;Pecina-Quintero et al, 2020Ruiz-Montoya et al, 2020), and single-nucleotide polymorphisms (SNPs) throughout the genome (Dupuis et al, 2019) have contributed to the understanding of the origin of mexfly populations and indicate mixed results stemming from the extent of the geographic range analyzed and in a lesser degree from the genetic markers (dominant-codominant) employed to survey populations. Particularly, at a small scale, AFLP markers detect very low (Nuevo León, Tamaulipas;Pecina-Quintero et al, 2009) or high genetic structure (Veracruz, Nuevo León, and Tamaulipas;Pecina-Quintero et al, 2020).…”

“…When using biochemical markers such as allozymes and surveying seven populations in the different States of Mexico, with different climates and vegetation types, low genetic structure for A. ludens was detected (Molina-Nery et al, 2014). In contrast, populations of this species in Chiapas, Mexico, show high genetic variation and low genetic structure between localities and moderate structure when populations are grouped by host plant used (Ruiz-Montoya et al, 2020). The latter results are in agreement with the findings of Ruiz-Arce et al (2015), they performed the most comprehensive phylogeographic study on the genetic structure of A. ludens to date, with two mitochondrial regions (COI and ND6) covering 67 populations along the whole range of the species and collections from the northern and southern 10.…”