The Roles of Mosquitoes in the Circulation of Monoxenous Trypanosomatids in Temperate Climates

Abstract

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.

Shining the spotlight on the neglected: new high-quality genome assemblies as a gateway to understanding the evolution of Trypanosomatidae

“…Indeed, O. modryi (referred to as TU6/7 C before the formal description) is restricted to the heteropteran family Alydidae [ 26 , 38 ]. In contrast, C. brevicula has a very wide host range and can successfully establish infections at least in phytophagous (Miridae) and predatory (Nabidae and Gerridae) true bugs, various flies (Antomyidae, Calliphoridae, Heleomyzidae, Muscidae, Sepsidae), as well as in mosquitoes (Culicidae) [ 19 , 39 – 41 ]. Undoubtedly, the host range cannot be the only factor explaining these differences and a thorough analysis of the genomic composition should better clarify the underlying reasons.…”

Multiple and frequent trypanosomatid co-infections of insects: the Cuban case study

“…Still, one aspect significantly complicates this picture, namely the observation that morphologically diverse flagellates are rather frequently encountered in a single insect host (Yurchenko et al, 2016;Frolov et al, 2017Frolov et al, , 2019. This finding was further corroborated by the serendipitous observation that trypanosomatids established in culture quite often differ from those detected by sequencing in the original host (Kostygov et al, 2011(Kostygov et al, , 2014, providing additional evidence of more than a single parasite species per host. Consequently, it can be assumed that using the PCR-based detection, genes from the most abundant flagellate species are preferentially amplified, with the co-occurring parasites going unnoticed.…”