Environmental constraints influencing survival of an African parasite in a north temperate habitat: effects of temperature on development within the host

Abstract

SUMMARYThe monogenean Protopolystoma xenopodis has been established in Wales for >40 years following introduction with Xenopus laevis from South Africa. This provides an experimental system for determining constraints affecting introduced species in novel environments. Parasite development post-infection was followed at 15, 20 and 25°C for 15 weeks and at 10°C for ≥1 year and correlated with temperatures recorded in Wales. Development was slowed/ arrested at ≤10°C which reflects habitat conditions for >6 months/ year. There was wide variation in growth at constant temperature (body size differing by >10 times) potentially attributable in part to genotype-specific host-parasite interactions. Parasite density had no effect on size but host sex did: worms in males were 1.8 times larger than in females. Minimum time to patency was 51 days at 25°C and 73 days at 20°C although some infections were still not patent at both temperatures by 105 days p.i. In Wales, fastest developing infections may mature within one summer (about 12 weeks), possibly accelerated by movements of hosts into warmer surface waters. Otherwise, development slows/stops in October-April, delaying patency to about 1 year p.i., while wide variation in developmental rates may impose delays of 2 years in some primary infections and even longer in secondary infections.

Interactions of warming and exposure affect susceptibility to parasite infection in a temperate fish species

“…Notwithstanding, as elevated temperatures can have both marked effects on the development rates of parasites in temperate regions (Tinsley et al 2011) and on fish immune function, disease resistance and fitness (Cramp et al 2014), then it is remains difficult to definitively decouple the effects of warming on these aspects of the infection dynamics from these data. It is thus recommended that these outputs serve as an initial assessment of the effects of warming temperatures and parasite exposure levels on these host–parasite dynamics, enabling the design of subsequent experiments of greater complexity that should enable, for example, greater assessment of how warming affects the development rate the parasite within hosts, such as their maturity (e.g.…”

Extinction of an introduced warm-climate alien species, Xenopus laevis, by extreme weather events

“…Water temperatures on the pond substrate in 2006–2008 were <10 °C for over 6 months each year (mid-October to late April), >15 °C for 4–5 months and >18 °C for only a few days (Tinsley et al 2011a ). Xenopus laevis may experience warmer conditions (but a greater risk of predation) in surface water in sunshine, up to 23 °C (Tinsley et al 2011b ).

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“…In Wales, there was no formal reaction to the presence of a breeding colony, and research published during 25 years did not attract conservation concerns. As a result, there is a substantial body of ecological findings including diet, growth rates, age determination, population biology and parasite infection (Tinsley and McCoid 1996 ; Measey and Tinsley 1998 ; Measey 1998 , 2001 ; Tinsley and Jackson 1998 ; Tinsley et al 2011a , b , 2012 ). When X. laevis was recorded in Lincolnshire, English Nature (now Natural England) began a programme in 2003 to eliminate the colony.…”

Environmental constraints influencing survival of an African parasite in a north temperate habitat: effects of temperature on egg development

“…This paper provides the background and presents results on stages developing in the external environment (a). A separate account records development of within-host stages (Tinsley et al 2011). The approach adopted has recorded the schedules of development of life-cycle stages taken from natural infections ‘in the wild’ and maintained under controlled environmental conditions in the laboratory.…”