High prevalence of Trypanosoma infection in Iberian green frogs (Pelophylax perezi) and evidence of a negative relationship between blood parasites and two indices of frog body condition

Abstract

Trypanosoma commonly parasitizes anuran hosts but very few studies have investigated ecological relationships in multiparasitized amphibians. We analysed a sample of 29 adult Iberian green frogs (Pelophylax perezi) from a monitored population in central Spain and found that 28 of these individuals (96.5%) were infected with blood parasites. The protozoa genera Lankesterella (Apicomplexa: Eimeriorina) (72.4%) and Trypanosoma (Euglenozoa: Trypanosomatida) (69%) had the highest prevalence, followed by an intraerythrocytic bacteria of the genus Aegyptianella (Pseudomonadota: Rickettsiales) (31.0%). We also report an infection by hematic microfilariae (Nematoda: Spirurida) (6.8%), which to our knowledge represents the first documented case in Iberian amphibians. Infections with more than one parasite type occurred in 62.1% of the frogs. A multimodel inference approach indicated that the infection intensities of Trypanosoma and Aegyptianella were the most important predictors, both negatively affecting the body condition of the frogs. Furthermore, the number of leeches that frogs had when captured showed a strong positive association with Trypanosoma infection intensity. This suggests that leeches act as primary vectors for Trypanosoma. Our results revealed a high taxonomic diversity of blood parasites in green frogs, thus contributing to expand our knowledge of the biodiversity of Mediterranean wetlands and highlighted the potential negative effects of certain infections on the fitness of these amphibian hosts.