title: Environmental constraints influencing survival of an African parasite in a north temperate habitat: effects of temperature on egg development.
abstract: Factors affecting survival of parasites introduced to new geographical regions include changes in environmental temperature. Protopolystoma xenopodis is a monogenean introduced with the amphibian Xenopus laevis from South Africa to Wales (probably in the 1960s) where low water temperatures impose major constraints on life-cycle processes. Effects were quantified by maintenance of eggs from infections in Wales under controlled conditions at 10, 12, 15, 18, 20 and 25°C. The threshold for egg viability/ development was 15°C. Mean times to hatching were 22 days at 25°C, 32 days at 20°C, extending to 66 days at 15°C. Field temperature records provided calibration of transmission schedules. Although egg production continues year-round, all eggs produced during >8 months/ year die without hatching. Output contributing significantly to transmission is restricted to 10 weeks (May-mid-July). Host infection, beginning after a time lag of 8 weeks for egg development, is also restricted to 10 weeks (July-September). Habitat temperatures (mean 15·5°C in summer 2008) allow only a narrow margin for life-cycle progress: even small temperature increases, predicted with 'global warming', enhance infection. This system provides empirical data on the metrics of transmission permitting long-term persistence of isolated parasite populations in limiting environments.
authors.affiliation: School of Biological Sciences, University of Bristol, Bristol BS8 1UG, UK. r.c.tinsley@bristol.ac.uk
authors.forename: R C
authors.initials: RC
authors.lastname: Tinsley
authors.forename: J E
authors.initials: JE
authors.lastname: York
authors.forename: A L E
authors.initials: AL
authors.lastname: Everard
authors.forename: L C
authors.initials: LC
authors.lastname: Stott
authors.forename: S J
authors.initials: SJ
authors.lastname: Chapple
authors.forename: M C
authors.initials: MC
authors.lastname: Tinsley
mesh_terms: D000818:Animals; D002470:Cell Survival; D004777:Environment; D005260:Female; D057232:Global Warming; D006790:Host-Parasite Interactions; D058865:Introduced Species; D008018:Life Cycle Stages; D010063:Ovum / Q000254:growth & development; D010986:Platyhelminths / Q000196:embryology / Q000254:growth & development*; D012621:Seasons; D013019:South Africa; D013696:Temperature; D013997:Time Factors; D014201:Trematode Infections / Q000469:parasitology / Q000662:veterinary*; D014852:Wales; D014867:Water / Q000469:parasitology; D014982:Xenopus laevis / Q000469:parasitology*
chemical_list: D014867:Water