Sexual differences in prevalence of a new species of trypanosome infecting túngara frogs

Abstract

Trypanosomes are a diverse group of protozoan parasites of vertebrates transmitted by a variety of hematophagous invertebrate vectors. Anuran trypanosomes and their vectors have received relatively little attention even though these parasites have been reported from frog and toad species worldwide. Blood samples collected from túngara frogs (Engystomops pustulosus), a Neotropical anuran species heavily preyed upon by eavesdropping frog-biting midges (Corethrella spp.), were examined for trypanosomes. Our results revealed sexual differences in trypanosome prevalence with female frogs being rarely infected (<1%). This finding suggests this protozoan parasite may be transmitted by frog-biting midges that find their host using the mating calls produced by male frogs. Following previous anuran trypanosome studies, we examined 18S ribosomal RNA gene to characterize and establish the phylogenetic relationship of the trypanosome species found in túngara frogs. A new species of giant trypanosome, Trypanosoma tungarae n. sp., is described in this study. Overall the morphometric data revealed that the trypomastigotes of T. tungarae n. sp. are similar to other giant trypanosomes such as Trypanosoma rotatorium and Trypanosoma ranarum. Despite its slender and long cell shape, however, 18S rRNA gene sequences revealed that T. tungarae n. sp. is sister to the rounded-bodied giant trypanosome, Trypanosoma chattoni. Therefore, morphological convergence explains similar morphology among members of two non-closely related groups of trypanosomes infecting frogs. The results from this study underscore the value of coupling morphological identification with molecular characterization of anuran trypanosomes.

Diversity and evolution of anuran trypanosomes: insights from the study of European species

“…Amphibian trypanosomes are very important from an evolutionary viewpoint. In accordance with the combined mode of life of their hosts, these parasites have both types of vectors: leeches as the trypanosomes of fish and dipterans as those of amniotes [ 17 – 19 ]. Therefore, this group was considered to be an intermediate, possibly even a connector between strictly aquatic (i.e.…”

Studying the sensory ecology of frog‐biting midges (Corethrellidae: Diptera) and their frog hosts using ecological interaction networks

“…Frog‐biting midges are also known to be vectors of trypanosomes (Johnson, Young & Butler, ; Bernal & Pinto, ; Meuche et al ., ) and thus the risk of infections might additionally influence the design of frog advertisement calls and calling behavior (Bernal et al ., ). Acoustic preferences of midges predict the rate of parasitism of their hosts (Meuche et al ., ) and midges are known to feed on body areas that maximize blood intake (de Silva, Jaramillo & Bernal, ).…”

Collateral damage or a shadow of safety? The effects of signalling heterospecific neighbours on the risks of parasitism and predation

“…Fringe-lipped bats often impose a lethal cost on signallers. Although parasitism by frog-biting midges has lower immediate costs, it is also important given the high numbers of midges attacking calling males [9], the substantial amounts of blood they can take from each signaller (XE Bernal 2010, unpublished data), and the fact that they can transmit blood parasites such as trypanosomes [23,24].…”