Podocotyle atomon (Trematoda: Digenea) impacts reproductive behaviour, survival and physiology in Gammarus zaddachi (Amphipoda)

Abstract

19The Trematoda are a group of phylogenetically diverse metazoan parasites that 20 exhibit complex life cycles that often pass through invertebrate and vertebrate hosts. 21Some trematodes influence their host's behaviour to benefit transmission. Their 22 parasitic influence may impact host population size by inhibiting an individual's 23 reproductive capacity. 24We assessed the impact of infection by Podocotyle atomon on the reproductive 25 behaviour and fecundity of its amphipod intermediate host, Gammarus zaddachi, 26 using laboratory and field studies. Parasite prevalence was high in the field, with 27 males more likely to be infected (prevalence in males 64%, in females 39%). Males 28 also suffered a higher parasite burden than females. Infected females were less 29 active, but we found no evidence for a reduction in female reproductive success. 30Infected females also had comparable pairing success to uninfected females. In 31 males, infection reduced survival and fecundity, with mortality being highest, and 32 sperm numbers lowest, in heavily infected individuals. Trematode parasites are 33 sometimes associated with altered host fecundity, but studies often lack the relevant 34 experimental data to explore the evolution of the trait. We discuss this among 35 information specific to the effect of P. atomon infection in G. zaddachi. 36 37

Metacollinia emscherin. sp., a novel sanguicolous apostome ciliate of freshwater amphipods (Gammarusspp.)

“…Generally, parasite prevalence in aquatic organisms, including amphipods, is positively correlated with host size, as older individuals are more likely to be exposed to infections over their lifespan (Poulin, 2000;Prati et al, 2023;Soldánová et al, 2010). Furthermore, size-asymmetric cannibalism, which is common in many aquatic taxa, including G. pulex, may potentially favor the transmission of parasites via ingestion of infected individuals (Arundell et al, 2019a(Arundell et al, , 2019bMacNeil et al, 2003;McGrath et al, 2007).…”

Fluctuating asymmetry, parasitism and reproductive fitness in two species of gammarid crustacean

“…2b). Visual identification of infection was deemed acceptable as it had previously been shown that 84.2% of animals with one or more visible cysts were PCR-positive for P. atomon infection and only one of 58 individuals with no visible cysts was PCR-positive (1.7%) (K. Arundell et al 2019).…”