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Autosexing strains to control populations of fruit flies (DIPTERA: Tephritidae): why do they fail to succeed?

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The development of a unique genetic sexing strain to control fruit fly populations has repetedly failed. But why do they fail to succed? We previously demonstrated in Certitis capitata (Wied.) that the autosexing mechanism must be developed on the germplasm of the population to be controled. The present integrative study addresses the causes for the lack of success, thus studying: 1- compatibility tests between Anastrepha fraterculus (Wied.) germplasms from different geographic origins; 2- the genotype by environment interaction component of phenotypic variation in A. fraterculus and 3- essential knowledge on polymorphisms of the Y-chromosome carrying the marker linked to male sex. Our hypothesis: a- chromosomal and morphological variants are associated to different argentinian geographic populations of C. capitata; b- chromosomal variants are not randomly distributed in A. fraterculus populations. We sampled guava fruits during 30 years to recover larvae and adult flies from both species, in order to study the chromosomal pattern of larvae from wild populations and derived strains. Banding patterns were obtained with routine and molecular cytogenetics. Sexual chromosome variants were associated to different strains. Analysis showed ten sexual chromosome variants in A. fraterculus. In C. capitata we found sexual chromosome polymorphisms for the X as well as for the Y. Our results -throughout the years- show the necessity of performing periodically genetic samplings of the populations to be treated in order to detect new mutations affecting mating beahaviour between laboratory and wild populations or lack of compatibiliy when applying the sterile male technique. The study of genotype by environment interaction parameter is mandatory to identify the right germplasms on which to develop the autosexing mechanism in order to successfully control populations of both fruit flies species.


molecular cytogenetics, genetic sexing, fruit flies, embryogenesis