Genetic structure and gene flow of the flea Xenopsylla cheopis in Madagascar and Mayotte

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Harimalala, Mireille Aurélie | Telfer, Sandra | Delatte, Hélène | Watts, Phillip, C | Miarinjara, Adélaïde | Ramihangihajason, Tojo, Rindra | Rahelinirina, Soanandrasana | Rajerison, Minoarisoa | Boyer, Sebastien

Edité par CCSD ; BioMed Central -

International audience. Background: The flea Xenopsylla cheopis (Siphonaptera: Pulicidae) is a vector of plague. Despite this insect’s medicalimportance, especially in Madagascar where plague is endemic, little is known about the organization of its naturalpopulations. We undertook population genetic analyses (i) to determine the spatial genetic structure of X. cheopis inMadagascar 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. cheopisdiffered, with the mean number of alleles per locus per population ranging from 1.78 to 4.44 and with moderate tohigh levels of genetic differentiation between populations. Three distinct genetic clusters were identified, with differentgeographical distributions but with some apparent gene flow between both islands and within Malagasy regions. Theapproximate Bayesian computation (ABC) used to test the predominant direction of flea dispersal implied a recentpopulation 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 fleaexchange 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 Madagascarrecently. As plague has not been reported in Mayotte, this introduction is unlikely to present a major concern forplague transmission. Nonetheless, evidence of connectivity among flea populations in the two islands indicates apossibility for dispersal by fleas in the opposite direction and thus a risk of plague introduction to Mayotte.

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