Genetic consequences of domestication and refreshment on colonies of the South American fruit fly

For almost a decade, natural populations of the South American fruit fly have been targeted for control through Sterile Insect Technique projects. To ensure a sustainable supply of competitive sterile flies for this approach, it is essential to understand the effects of domestication when strains of this pest are initially brought into the laboratory to establish colonies as well as the changes occurring after multiple generations of adaptation to conditions used for mass rearing. Using one colony established from a wild population of the Brazil-1 morphotype (WIL) and two from laboratory colonies in Brazil known as the Piracicaba (PL) and Vacaria (VL) strains, this study evaluated genetic diversity in samples from 10 generations after domestication and maintenance under semimass rearing conditions. Another aim of this study was to analyze changes in the genetic makeup of the colonies of the two laboratory strains after refreshment. Eight microsatellite markers were used for the genetic analyses. Results indicated a moderate but significant amount of genetic differentiation between the WIL population and the two laboratory strains. Results also showed that levels of genetic diversity in both the VL and PL strains were maintained at similar levels over a period of more than two years of rearing. Additionally, results suggest that successful creation of admixture via refreshment is more likely to be beneficial in relatively short-term domesticated colonies, and that performing refreshment approximately every six to eight generations could be beneficial to maintain the genetic diversity of A. fraterculus colonies under laboratory mass rearing conditions.