Mating compatibility among different wild and laboratory strains of the Brazil-1 morphotype of Anastrepha fraterculus (Diptera: Tephritidae)

In cases where a pest that is target of a Sterile Insect Technique (SIT) campaign is a member of a cryptic species complex, it is necessary to know in advance whether the sterile mass-reared males are sexually compatible with the wild females, otherwise the releases would result in failure to induce sterility in the target population. The South American fruit fly, commonly known as Anastrepha fraterculus, represents such a complex of cryptic species with at least 8 different morphotypes. From northern Argentina to southeastern areas of Brazil, the "Brazil-1" morphotype predominates and laboratory colonies have been established for its control through the use of SIT. Our goal was to assess the mating compatibility between different populations, including two wild ones from southern Brazil (Vacaria-WV; and Pelotas-WP) and laboratory strains derived from this morphotype. These included two bisexual laboratory strains (Piracicaba-PIRA; and Vacaria-VAC), and a recently developed genetic sexing strain, the GSS-89. Field cage tests with fertile flies demonstrated that PIRA flies present partial sexual incompatibility with all other strains, and therefore cannot be recommended for SIT field release. Also, males of the VAC strain, both fertile and sterile, mated randomly with WV and WP flies. No evidence of sexual isolation was found between the flies of the GSS and WV flies, but a certain level of incompatibility was shown between the fertile or sterile GSS males and WP females. Recommendations on the use of those strains through the SIT against the two southern Brazilian populations were made.