Аннотация:Monoxenous (insect-restricted) trypanosomatids are highly diverse and abundant in nature.
While many papers focus on the taxonomy and distribution of these parasites, studies on their biology
are still scarce. In particular, this concerns trypanosomatids inhabiting the ubiquitous mosquitoes. To
shed light on the circulation of monoxenous trypanosomatids with the participation of mosquitoes, we
performed a multifaceted study combining the examination of naturally- and experimentally-infected
insects using light and electron microscopy and molecular identification of parasites. Our examination
of overwintering mosquitoes (genera Culex and Culiseta) revealed that their guts contained living
trypanosomatids, which can be spread during the next season. Experimental infections with Crithidia
spp. demonstrated that imagines represent permissive hosts, while larvae are resistant to these
parasites. We argue that for the parasites with wide specificity, mosquitoes act as facultative hosts.
Other trypanosomatids may have specific adaptations for vertical transmission in these insects at the
expense of their potential to infect a wider range of hosts and, consequently, abundance in nature.