Fleas (Siphonaptera) of Gerbils in the Caucasus

Gerbils (subfamily Gerbillinae) are the main component of biocenoses in deserts and semi-deserts. They are hosts of many flea species and the main pathogen carriers in a number of natural plague foci. This review is focused on taxonomic diversity, distribution pattern, and host-parasite relationships of the flea species recorded as parasites of gerbils in the Caucasus. Gerbils and their fleas migrated to the Caucasus from West Asia in the Pliocene, simultaneously with the psammophytic floral complexes. In the Holocene, semi-desert and desert Turanian plants were introduced to Ciscaucasia from the northeast, while the fauna of gerbils and their fleas was supplemented with several more species and subspecies. In accordance with the spread of plague carriers and vectors, the gerbil-based natural plague foci could have existed in Transcaucasia already in the Pliocene, but those in Ciscaucasia were formed no earlier than the Holocene.