Population structure of Glossina palpalis gambiensis (Diptera: Glossinidae) between river basins in Burkina Faso: consequences for area-wide integrated pest management.
ABSTRACT African animal trypanosomosis is a major obstacle to the development of more efficient and sustainable livestock production systems in West Africa. Riverine tsetse species such as Glossina palpalis gambiensis Vanderplank are their major vectors. A wide variety of control tactics is available to manage these vectors, but their elimination will only be sustainable if control is exercised following area-wide integrated pest management (AW-IPM) principles, i.e. the control effort is targeting an entire tsetse population within a circumscribed area. In the present study, genetic variation at microsatellite DNA loci was used to examine the population structure of G. p. gambiensis inhabiting two adjacent river basins, i.e. the Comoé and the Mouhoun River basins in Burkina Faso. A remote sensing analysis revealed that the woodland savannah habitats between the river basins have remained unchanged during the last two decades. In addition, genetic variation was studied in two populations that were separated by a man-made lake originating from a dam built in 1991 on the Comoé. Low genetic differentiation was observed between the samples from the Mouhoun and the Comoé River basins and no differentiation was found between the samples separated by the dam. The data presented indicate that the overall genetic differentiation of G. p. gambiensis populations inhabiting two adjacent river basins in Burkina Faso is low (F(ST)=0.016). The results of this study suggest that either G. p. gambiensis populations from the Mouhoun are not isolated from those of the Comoé, or that the isolation is too recent to be detected. If elimination of the G. p. gambiensis population from the Mouhoun River basin is the selected control strategy, re-invasion from adjacent river basins may need to be prevented by establishing a buffer zone between the Mouhoun and the other river basin(s).
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ABSTRACT: Microsatellite loci are usually considered to be neutral co-dominant and Mendelian markers. We undertook to study the inheritance of five microsatellite loci in the European Lyme disease vector, the tick Ixodes ricinus. Only two loci appeared fully Mendelian while the three others displayed non-Mendelian patterns that highly frequent null alleles could not fully explain. At one locus, IR27, some phenomenon seems to hinder the PCR amplification of one allele, depending on its origin (maternal imprinting) and/or its size (short allele dominance). DNA methylation, which appeared to be a possible explanation of this amplification bias, was rejected by a specific test comparing the amplification efficiency that did not differ between unmethylated and experimentally methylated DNA. The role of allele size in heterozygous individuals was then revealed from the data available on field collected ticks and consistent with the results of a theoretical approach. These observations highlight the need for prudence while inferring reproductive systems (selfing rates), parentage or even allelic frequencies from microsatellite markers, in particular for parasitic organisms for which molecular approaches often represent the only way for population biology inferences.International Journal for Parasitology 08/2004; 34(8):943-50. · 3.64 Impact Factor
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ABSTRACT: We examine the power of different exact tests of differentiation for diploid populations. Since there is not necessarily random mating within populations, the appropriate hypothesis to construct exact tests is that of independent sampling of genotypes. There are two categories of tests, FST-estimator tests and goodness of fit tests. In this latter category, we distinguish "allelic statistics", which account for the nature of alleles within genotypes, from "genotypic statistics" that do not. We show that the power of FST-estimator tests and of allelic goodness of fit tests are similar when sampling is balanced, and higher than the power of genotypic goodness of fit tests. When sampling is unbalanced, the most powerful tests are shown to belong to the allelic goodness of fit group.Genetics 01/1997; 144(4):1933-40. · 4.39 Impact Factor
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ABSTRACT: ldne is a program with a Visual Basic interface that implements a recently developed bias correction for estimates of effective population size (N(e) ) based on linkage disequilibrium data. The program reads genotypic data in standard formats and can accommodate an arbitrary number of samples, individuals, loci, and alleles, as well as two mating systems: random and lifetime monogamy. ldne calculates separate estimates using different criteria for excluding rare alleles, which facilitates evaluation of data for highly polymorphic markers such as microsatellites. The program also introduces a jackknife method for obtaining confidence intervals that appears to perform better than parametric methods currently in use.Molecular Ecology Resources 07/2008; 8(4):753-6. · 7.43 Impact Factor