Effect of sampling methods, effective population size and migration rate estimation in Glossina palpalis palpalis from Cameroon.
Human and animal trypanosomiases are two major constraints to development in Africa. These diseases are mainly transmitted by tsetse flies in particular by Glossina palpalis palpalis in Western and Central Africa. To set up an effective vector control campaign, prior population genetics studies have proved useful. Previous studies on population genetics of G. p. palpalis using microsatellite loci showed high heterozygote deficits, as compared to Hardy-Weinberg expectations, mainly explained by the presence of null alleles and/or the mixing of individuals belonging to several reproductive units (Wahlund effect). In this study we implemented a system of trapping, consisting of a central trap and two to four satellite traps around the central one to evaluate a possible role of the Wahlund effect in tsetse flies from three Cameroon human and animal African trypanosomiases foci (Campo, Bipindi and Fontem). We also estimated effective population sizes and dispersal. No difference was observed between the values of allelic richness, genetic diversity and Wright's FIS, in the samples from central and from satellite traps, suggesting an absence of Wahlund effect. Partitioning of the samples with Bayesian methods showed numerous clusters of 2-3 individuals as expected from a population at demographic equilibrium with two expected offspring per reproducing female. As previously shown, null alleles appeared as the most probable factor inducing these heterozygote deficits in these populations. Effective population sizes varied from 80 to 450 individuals while immigration rates were between 0.05 and 0.43, showing substantial genetic exchanges between different villages within a focus. These results suggest that the "suppression" with establishment of physical barriers may be the best strategy for a vector control campaign in this forest context.
University of Yaounde I, Laboratory of Parasitology and Ecology, Faculty of Science, BP 812 Yaounde, Cameroon.
Tanekou Tito Trésor
TT
Mélachio
University of Yaounde I, Laboratory of Parasitology and Ecology, Faculty of Science, BP 812 Yaounde, Cameroon.
Flobert
F
Njiokou
Institut de Recherche pour le Développement (IRD), UMR IRD/CIRAD 177 INTERTRYP, TA A-17/G, Campus International de Baillarguet, 34398 Montpellier Cedex 5, France.
Sophie
S
Ravel
Molecular Parasitology and Entomology Unit, Department of Biochemistry, Faculty of Science, University of Dschang, Dschang, Cameroon.
Gustave
G
Simo
Institut de Recherche pour le Développement (IRD), UMR IRD/CIRAD 177 INTERTRYP, TA A-17/G, Campus International de Baillarguet, 34398 Montpellier Cedex 5, France; UMR 177 IRD/CIRAD INTERTRYP, Centre International de Recherche-Développement sur l'Elevage en zone Subhumide (CIRDES), 01 BP 454 Bobo-Dioulasso 01, Burkina Faso.
Philippe
P
Solano
Institut de Recherche pour le Développement (IRD), UMR IRD/CIRAD 177 INTERTRYP, TA A-17/G, Campus International de Baillarguet, 34398 Montpellier Cedex 5, France; UMR 177 IRD/CIRAD INTERTRYP, Centre International de Recherche-Développement sur l'Elevage en zone Subhumide (CIRDES), 01 BP 454 Bobo-Dioulasso 01, Burkina Faso. Electronic address: thierry.demeeus@ird.fr.
Thierry
T
De Meeûs
D000483:Alleles; D000818:Animals; D002163:Cameroon; D005843:Geography; D006801:Humans; D011156:Population Density; D011157:Population Dynamics; D014353:Trypanosomiasis, African / Q000635:transmission; D014370:Tsetse Flies / Q000235:genetics / Q000469:parasitology
Effective population size; Glossina palpalis palpalis; Heterozygote deficits; Migration rate; Sampling methods; Wahlund effect