Vol. 64, 2025

Leech Infestation Patterns between Native and Invasive Freshwater Turtles: Implications for Invasion Success

Sabine B. Rocha^1,*, Carlos Rouco², Nayara Louback-Franco

³, Carlos Eduardo V. Grou

⁴,

^4,5

¹Department of Botany, Ecology and Plant Physiology, Universidad de Córdoba, Carretera N-IV km, 396, 14014, Córdoba, Spain. *Correspondence: E-mail: sabine.borges@gmail.com (Rocha)
²Department of Plant Biology and Ecology, Universidad de Sevilla, Avenida Reina Mercedes, 6, 41012, Seville, Spain. E-mail: c.rouco@gmail.com (Rouco)
³Programa de Pós-graduação em Ecologia, Universidade Federal do Pará, Rua Augusto Corrêa, 01, 66075-110, Belém, Brazil. E-mail: nayara993@gmail.com (Louback-Franco)
⁴Programa de Pós-graduação em Biologia Comparada, Universidade Estadual de Maringá, Avenida Colombo, 5790, 87020-900, Maringá, Brazil. E-mail: eduardovargasgrou@gmail.com (Grou); takemotorm@nupelia.uem.br (Takemoto)
⁵Núcleo de Pesquisas em Limnologia, Ictiologia e Aqüicultura, Universidade Estadual de Maringá, Avenida Colombo, 5790, 87020-900, Maringá, Brazil

(Received 9 January 2025 / Accepted 29 May 2025 / Published -- 2025)
Communicated by Huiyu Wang

The increasing global introduction of alien species in recent decades underscores the need to understand the factors driving their establishment and spread in order to mitigate their ecological impacts. As alien species often thrive due to the absence of natural enemies (e.g., parasites), we investigated leech parasitism in freshwater turtles, focusing on an assemblage with over 10 years of co-occurrence between native species (Phrynops geoffroanus, Hydromedusa tectifera) and invasive sliders (Trachemys dorbigni, Trachemys scripta elegans). We used traps to capture 62 turtles to assess host characteristics (species, sex, body size, and body region) that influence leech prevalence and infestation intensity in southern Brazil. Our findings revealed that native turtles exhibited an 18-fold higher prevalence of hematophagous leech than invasive species, with T. dorbigni being the only species in which no leech infestation was observed. Infestation intensity also varied among species, with native turtles harboring more leeches.  robability of leech infestation increased with body size, and the hind limbs were significantly more infested. The diminished presence of ectoparasites on invasive Trachemys throughout this coexistence period supports the enemy release hypothesis, suggesting that the lack of natural enemies may be a potential driver facilitating their invasion success. These results provide baseline data for future studies exploring key factors in the success of the slider invasions.

Keywords: Aquatic biodiversity, Host-parasite interaction, Invasive species, Parasitism, Testudines

Citation: Rocha SB, Rouco C, Louback-Franco N, Grou CEV, Takemoto RM. 2025. Leech infestation patterns between native and invasive freshwater turtles: implications for invasion success. Zool Stud 64:32.