Genetic differentiation of the oriental rat flea, Xenopsylla cheopis, from two sympatric host species

Abstract

Abstract Background The oriental rat flea (Xenopsylla cheopis), which infests several mammals, primarily rats (Rattus spp.), is the most notorious vector of human plague. In this study, we measured the genetic differentiation among populations of fleas from the Asian house rat (Rattus tanezumi) and the brown rat (R. norvegicus) using microsatellite markers in order to investigate the extent of host-switching in this parasite. Results We developed 11 polymorphic microsatellite loci for our study, nine of which showed high potential for inbreeding. AMOVA showed that the majority (84.07%, P 0.05). Analyses of the pairwise fixation index revealed that most of the ten allopatric population pairs but none of the five sympatric population pairs were significantly differentiated. Moreover, based on genetic structure clustering analysis, there was obvious differentiation between allopatric populations but not between sympatric population pairs. Conclusions These results indicate the presence of frequent migrations of the oriental rat flea between the sympatric Asian house rat and brown rat, causing a high rate of gene flow and limited genetic differentiation. We suggest that there is no clear boundary limiting the migration of oriental rat fleas between the two hosts, and thus both rat species should be monitored equally for the purposes of plague prevention and control.

Keywords

• Xenopsylla cheopis
• Plague
• Microsatellites
• Genetic differentiation
• Sympatric populations