Does the Trematode parasite Coitocaecum parvum adopt different life history strategies in different amphipod hosts?
2012 Does the Trematode parasite Coitocaecum parvum adopt different life history strategies in different amphipod hosts? RUIZ DANIELS Rose (United Kingdom) firstname.lastname@example.org
Organisation: University of Poitiers, Poitiers (FR) - University of Otago, Dunedin (New Zealand) Supervisor : Robert Poulin (UO) & Sophie Beltran (UP)
Summary: Parasite-host relationships present interesting model systems to study rapid co- evolutionary responses since the interaction between the host and its parasite will influence parasitic infection patterns and strategies. The trematode parasite Coitocaecum parvum can negate the need for a third host by undergoing progenesis or self-fertilisation in its second intermediate host. C. parvum has two possible second amphipod intermediate hosts. Paracalliope fluviatilis and Paracorophium excavatum that inhabit the same area but show differences in size and ecology. In this study the infection behaviour of C. parvum was explored in the two amphipod hosts, to determine if the incidence of adoption of progenesis by the parasite varies in these two hosts, and in the case of C. parvum that adopt progenesis, to determine if the number of eggs produced is higher for those living inside the larger host P. excavatum than in the smaller host P. fluviatilis. It was found that C. parvum are just as likely to become progenetic in either of the two amphipod hosts, but that P. excavatum has a higher prevalence of C. parvum and other parasites like Microphallus sp. It was also found that the only factor that affects the chances of C. parvum becoming progenetic is the host size. the larger the size of the host, the greater the chance of the parasite becoming progenetic. This result seems to be related to resource constraints that would be the most limiting factor. Progenetic metacercariae fitness (eggs produced) is also influenced by the nature of the other parasites they share their host with. This study raises new and interesting questions about parasite host exploitation.