Microsatellite markers from the ‘South American fruit fly’ Anastrepha fraterculusa: valuable tool for population genetic analysis and SIT applications

Background: Anastrepha fraterculus Wiedemann is a horticultural pest which causes significant economic losses in the fruit-producing areas of the American continent and limits the access of products to international markets. The use of environmentally friendly control strategies against this pest is constrained due to the limited knowledge of its population structure. Results: We developed microsatellite markers for A. fraterculus from four genomic libraries, which were enriched in CA, CAA, GA and CAT microsatellite motifs. Fifty microsatellite regions were evaluated and 14 loci were selected for population genetics studies. Genotypes of 122 individuals sampled from four A. fraterculus populations were analyzed. The level of polymorphism ranged from three to 13 alleles per locus and the mean expected heterozygosity ranged from 0.60 to 0.64. Comparison between allelic and genotypic frequencies showed significant differences among all pairs of populations. Conclusions: This novel set of microsatellite markers provides valuable information for the description of genetic variability and population structure of wild populations and laboratory strains of A. fraterculus. This information will be used to identify and characterize candidate strains suitable to implement effective pest control strategies and might represent a first step towards having a more comprehensive knowledge about the genetics of this pest.Instituto de GenéticaFil: Lanzavecchia, Silvia Beatriz. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Genética. Laboratorio de Genética de Insectos de Importancia Económica; ArgentinaFil: Juri, Marianela Lucía. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Genética. Laboratorio de Genética de Insectos de Importancia Económica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Bonomi, Angelica. Universitá di Pavia, Dipartimento di Biologia e Biotecnologie ‘L. Spallanzani’; ItaliaFil: Scannapieco, Alejandra Carla. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Genética. Laboratorio de Genética de Insectos de Importancia Económica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Segura, Diego Fernando. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Genética. Laboratorio de Genética de Insectos de Importancia Económica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Cladera, Jorge Luis. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Genética. Laboratorio de Genética de Insectos de Importancia Económica; ArgentinaFil: Gasperi, Giuliano. Universitá di Pavia, Dipartimento di Biologia e Biotecnologie ‘L. Spallanzani’; ItaliaFil: Gomulski, Ludvik. Universitá di Pavia, Dipartimento di Biologia e Biotecnologie ‘L. Spallanzani’; ItaliaFil: Malacrida, Anna. Universitá di Pavia, Dipartimento di Biologia e Biotecnologie ‘L. Spallanzani’; Itali

Interchromosomal Duplications on the Bactrocera oleae Y Chromosome Imply a Distinct Evolutionary Origin of the Sex Chromosomes Compared to Drosophila

BACKGROUND: Diptera have an extraordinary variety of sex determination mechanisms, and Drosophila melanogaster is the paradigm for this group. However, the Drosophila sex determination pathway is only partially conserved and the family Tephritidae affords an interesting example. The tephritid Y chromosome is postulated to be necessary to determine male development. Characterization of Y sequences, apart from elucidating the nature of the male determining factor, is also important to understand the evolutionary history of sex chromosomes within the Tephritidae. We studied the Y sequences from the olive fly, Bactrocera oleae. Its Y chromosome is minute and highly heterochromatic, and displays high heteromorphism with the X chromosome. METHODOLOGY/PRINCIPAL FINDINGS: A combined Representational Difference Analysis (RDA) and fluorescence in-situ hybridization (FISH) approach was used to investigate the Y chromosome to derive information on its sequence content. The Y chromosome is strewn with repetitive DNA sequences, the majority of which are also interdispersed in the pericentromeric regions of the autosomes. The Y chromosome appears to have accumulated small and large repetitive interchromosomal duplications. The large interchromosomal duplications harbour an importin-4-like gene fragment. Apart from these importin-4-like sequences, the other Y repetitive sequences are not shared with the X chromosome, suggesting molecular differentiation of these two chromosomes. Moreover, as the identified Y sequences were not detected on the Y chromosomes of closely related tephritids, we can infer divergence in the repetitive nature of their sequence contents. CONCLUSIONS/SIGNIFICANCE: The identification of Y-linked sequences may tell us much about the repetitive nature, the origin and the evolution of Y chromosomes. We hypothesize how these repetitive sequences accumulated and were maintained on the Y chromosome during its evolutionary history. Our data reinforce the idea that the sex chromosomes of the Tephritidae may have distinct evolutionary origins with respect to those of the Drosophilidae and other Dipteran families

Polyandry Is a Common Event in Wild Populations of the Tsetse Fly Glossina fuscipes fuscipes and May Impact Population Reduction Measures

Glossina fuscipes fuscipes is the most common tsetse species in Uganda where it is responsible for transmitting Trypanosoma brucei rhodensiense and Trypanosoma brucei gambiense parasites causing sleeping sickness in humans in addition to related trypanosomes that cause Nagana in cattle. An understanding of the reproductive biology of this vector is essential for the application of sustainable control/eradication methods such as Sterile Insect Technique (SIT). We have analysed the number of times a female mates in the wild as this aspect of the reproductive behaviour may affect the stability and size of populations. We provide evidence that remating is a common event in the wild and females store sperm from multiple males, which may potentially be used for insemination. In vector eradication programmes, re-infestation of cleared areas and/or in cases of residual populations, the occurrence of remating may unfortunately enhance the reproductive potential of the re-invading propagules. We suggest that population age structure may influence remating frequency. Considering the seasonal demographic changes that this fly undergoes during the dry and wet seasons, control programmes based on SIT should release large numbers of sterile males, even in residual surviving target populations, in the dry season

Development of SCAR markers in Psyttalia concolor for strains and populations analysis.

none7Tematica Ex SIR: Studio della variabilità genetica in insetti d'interesse economico. (Classif. Ex SIR:Articoli in atti di congresso Estero ) Xth European Congress on Insect Parasitoids, 17-21 SeptemberKaram Nissrine; Guglielmino Carmela R.; Bertin Sabrina; Bonomi Alessandro; Baldacchino F; Simeone V; Malacrida Anna RodolfaKaram, Nissrine; Guglielmino, Carmela; Bertin, Sabrina; Bonomi, Alessandro; Baldacchino, F; Simeone, V; Malacrida, ANNA RODOLF

Microsatellite markers from the 'South American fruit fly' Anastrepha fraterculus: a valuable tool for population genetic analysis and SIT applications

Background: Anastrepha fraterculus Wiedemann is a horticultural pest which causes significant economic losses in the fruit-producing areas of the American continent and limits the access of products to international markets. The use of environmentally friendly control strategies against this pest is constrained due to the limited knowledge of its population structure. Results: We developed microsatellite markers for A. fraterculus from four genomic libraries, which were enriched in CA, CAA, GA and CAT microsatellite motifs. Fifty microsatellite regions were evaluated and 14 loci were selected for population genetics studies. Genotypes of 122 individuals sampled from four A. fraterculus populations were analyzed. The level of polymorphism ranged from three to 13 alleles per locus and the mean expected heterozygosity ranged from 0.60 to 0.64. Comparison between allelic and genotypic frequencies showed significant differences among all pairs of populations. Conclusions: This novel set of microsatellite markers provides valuable information for the description of genetic variability and population structure of wild populations and laboratory strains of A. fraterculus. This information will be used to identify and characterize candidate strains suitable to implement effective pest control strategies and might represent a first step towards having a more comprehensive knowledge about the genetics of this pest

Sperm storage and use in polyandrous females of the globally invasive fruitfly, Ceratitis capitata

The medfly, Ceratitis capitata, is an invasive species in which polyandry, associated with sperm precedence, is a common behaviour in the wild. In this species, characterized by internal fertilization, we disclose how the sperm from two males are stored in the female storage organs and how they are used in terms of paternity outcome. The experiments were designed to furnish comparable and unbiased estimates of sperm numbers and progeny in twice-mated females. Results are incorporated in a model through which it is possible to relate the amount of stored sperm with the progeny of twice-mated females. The results show that polyandrous medfly females conserve equal amounts of sperm from the two males to fertilize their eggs. However, we observed a clear advantage of the second male's sperm in siring progeny, which interestingly decreases in favor of the first male as ovipositions progress. The results enable us to exclude differential sperm mortality and suggest that it is the mechanics governing the storage organs which causes the initial, but decreasing second male sperm precedence during the female reproductive life. These outcomes allow us to correlate sperm use in polyandrous females with the mating strategies and invasiveness of this fly