Ixodes persulcatus/pavlovskyinatural hybrids in Siberia: Occurrence in sympatric areas and infection by a wide range of tick-transmitted agents

Ixodes persulcatusand Ixodes pavlovskyiticks, two closely related species of the I. ricinus - I. persulcatusgroup, are widely distributed in the southern part of Western Siberia. Recently, the existence of natural hybrids of I. persulcatusand I. pavlovskyiticks has been demonstrated. The aim of this study was to evaluate the abundance of I. persulcatus/pavlovskyihybrids in several locations with different ratios of parental tick species and to investigate the prevalence and genetic variability of a wide range of infectious agents in these hybrids compared to the parental tick species. Natural hybrids of I. persulcatusand I. pavlovskyiticks were identified in all examined locations in Altai and Novosibirsk, Western Siberia, Russia. The abundance of hybrids varied from 7% to 40% in different locations and was maximal in a location with similar proportions of I. persulcatusand I. pavlovskyiticks. For the first time, it was shown that hybrids can be infected with the same agents as their parental tick species: tick-borne encephalitis and Kemerovo viruses, Borrelia afzelii, Borrelia bavariensis, Borrelia garinii, Borrelia miyamotoi, Rickettsia helvetica, Rickettsia raoultii, Rickettsia sibirica, “CandidatusRickettsia tarasevichiae”, Anaplasma phagocytophilum, Ehrlichia muris, “CandidatusNeoehrlichia mikurensis”, and Babesia microti.The prevalence of most bacterial agents in hybrids was intermediate compared to their parental tick species. Most genetic variants of the identified agents have been previously found in the parental tick species. Wide distribution of I. persulcatus/pavlovskyinatural hybrids implies that I. persulcatus, I. pavlovskyiand their hybrids coexist in all I. persulcatus- I. pavlovskyisympatric areas.