Genetic structure and gene flow of the flea Xenopsylla cheopis in Madagascar and Mayotte
Abstract
Background: The flea Xenopsylla cheopis (Siphonaptera: Pulicidae) is a vector of plague. Despite this insect’s medical
importance, especially in Madagascar where plague is endemic, little is known about the organization of its natural
populations. We undertook population genetic analyses (i) to determine the spatial genetic structure of X. cheopis in
Madagascar and (ii) to determine the potential risk of plague introduction in the neighboring island of Mayotte.
Results: We genotyped 205 fleas from 12 sites using nine microsatellite markers. Madagascan populations of X. cheopis
differed, with the mean number of alleles per locus per population ranging from 1.78 to 4.44 and with moderate to
high levels of genetic differentiation between populations. Three distinct genetic clusters were identified, with different
geographical distributions but with some apparent gene flow between both islands and within Malagasy regions. The
approximate Bayesian computation (ABC) used to test the predominant direction of flea dispersal implied a recent
population introduction from Mayotte to Madagascar, which was estimated to have occurred between 1993 and 2012.
The impact of this flea introduction in terms of plague transmission in Madagascar is unclear, but the low level of flea
exchange between the two islands seems to keep Mayotte free of plague for now.
Conclusion: This study highlights the occurrence of genetic structure among populations of the flea vector of plague,
X. cheopis, in Madagascar and suggests that a flea population from Mayotte has been introduced to Madagascar
recently. As plague has not been reported in Mayotte, this introduction is unlikely to present a major concern for
plague transmission. Nonetheless, evidence of connectivity among flea populations in the two islands indicates a
possibility for dispersal by fleas in the opposite direction and thus a risk of plague introduction to Mayotte.
Fichier principal
Genetic structure and gene flow of the flea Xenopsylla cheopis in Madagascar and mayotte_2017.pdf (1.05 Mo)
Télécharger le fichier
Origin : Publisher files allowed on an open archive
Loading...