Authors: Tommy L F Leung Robert Poulin
Publish Date: 2007/02/10
Volume: 101, Issue: 2, Pages: 281-287
Abstract
The rate at which host organisms accumulate parasites is affected by a number of intrinsic and extrinsic factors The New Zealand cockle Austrovenus stutchburyi is frequently parasitised by trematodes comprising of two species of echinostomes and a species of gymnophallid that use it as a second intermediate host for trophic transmission to avian definitive hosts The echinostomes are capable of manipulating the burrowing behaviour of the cockle to enhance their transmission success whereas the gymnophallid is not capable of host manipulation Previous studies have found patterns of positive associations between the echinostomes and the gymnophallid Thus it is possible that the latter is a “hitchhiking” parasite that preferentially infects cockles already heavily infected by echinostome metacercariae to enhance its own transmission rate A field experiment involving cockles forced to remain either above or below the sediment surface to simulate manipulated and nonmanipulated cockles was conducted to test the hitchhiking hypothesis The gymnophallid was not found to display any preference for either surfaced or buried cockles therefore it cannot be considered as a hitchhiking parasite Possible alternative reasons for the pattern of positive association between the gymnophallid and the echinostomes are proposedThe authors would like to thank Florian Weller for providing assistance with setting up the field experiment and Clément Lagrue and Kim BryanWalker for help with the maintenance of the cockle cages The experiments conducted for this study comply with the current laws of New Zealand
Keywords: