title: Changes in survival characteristics of Diplostomum spathaceum cercariae emerged from cadmium-exposed Lymnaea stagnalis.
abstract: The effect of exposing Lymnaea stagnalis (Gastropoda: Pulmonata), infected with Diplostomum spathaceum (Trematoda: Diplostomatidae), to 100 microg l(-1) cadmium for 7 days on survival characteristics (survival, tail loss, decaudized cercarial life-span) of emerged cercariae was investigated. Exposure of L. stagnalis to cadmium resulted in significantly increased D. spathaceum cercarial survival and an inhibited tail loss compared to controls. The normal parallel relationship which exists over time between decreasing cercarial survival and increasing tail loss in controls was changed in cercariae from cadmium-exposed hosts with an increased proportion of cercarial deaths occurring without tail loss. The decaudized cercarial life-span over the survival period of the cercarial population did not significantly change. However comparisons between individuals decaudized during the initial 24 h time period with those which were decaudized during the final period of cercarial survival showed a significantly altered life span which did not occur in the control population. As a potential indicator of penetration 'fitness' comparisons were also undertaken between control and exposed cercariae decaudized during the initial 24 h time period, which revealed that the decaudized cercarial life-span from the exposed hosts was significantly different from controls. This may have important implications for the ability of cercariae to migrate through the tissues of their target host. The importance and relevance of these results to parasite transmission are discussed.
authors.affiliation: School of Biological Sciences, Royal Holloway, University of London, Egham, Surrey, TW20 0EX, UK. n.morley@rhul.ac.uk
authors.forename: N J
authors.initials: NJ
authors.lastname: Morley
authors.forename: M
authors.initials: M
authors.lastname: Crane
authors.forename: J W
authors.initials: JW
authors.lastname: Lewis
mesh_terms: D000818:Animals; D002104:Cadmium / Q000633:toxicity*; D004305:Dose-Response Relationship, Drug; D004781:Environmental Exposure; D006790:Host-Parasite Interactions; D008018:Life Cycle Stages; D008195:Lymnaea / Q000469:parasitology*; D013623:Tail; D014200:Trematoda / Q000187:drug effects*; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D014874:Water Pollutants, Chemical; D002104:Cadmium