The effect of the acanthocephalan parasite Pomphorhynchus laevis on the lipid and glycogen content of its intermediate host Gammarus pulex

Besides conspicuous changes in behaviour, manipulative parasites may also i nduce subtle physiological effects in the host that may also be favourable to the parasite. In particular. parasites may be able to influence the re-a llocation of resources in their own favour. We studied the association betw een the presence of the acanthocephalan parasite. Pomphorhynchus laevis, an d inter-individual variation in the lipid and glycogen content of its crust acean host. Gammarus pulex (Amphipoda). Infected gravid females had signifi cantly lower lipid contents than uninfected females, but there was no diffe rence in the lipid contents of non-gravid females and males that were infec ted with P. laevis. In contrast, we found that all individuals that were pa rasitised by P. laevis had significantly increased glycogen contents, indep endent of their sex and reproductive status. We discuss our results in rela tion to sex-related reproductive strategies of hosts. and the influence the y may have on the level of conflict over energy allocation between the host and the parasite. (C) 2001 Australian Society for Parasitology Inc. Publis hed by Elsevier Science Ltd. All rights reserved.