School of Biological Sciences, University of Bristol, Bristol BS8 1UG, UK.
Parasitology. 2011 Jul;138(8):1039-52. doi: 10.1017/S0031182011000424.
The 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.
单殖吸虫原多盘虫（Protopolystoma xenopodis）自 1970 年代从南非随非洲爪蟾（Xenopus laevis）引入威尔士以来已存在超过 40 年。这为确定影响新环境中引入物种的限制因素提供了一个实验系统。在感染后 15、20 和 25°C 下进行了 15 周的寄生虫发育情况监测，并在 10°C 下进行了 ⩾1 年的监测，同时与威尔士记录的温度相关联。在 ⩽10°C 时，寄生虫的发育速度会减缓/停止，这反映了每年超过 6 个月的栖息地条件。在恒温下，生长差异很大（体型相差 ⁇ 10 倍以上），这可能部分归因于基因型特异性的宿主-寄生虫相互作用。寄生虫密度对体型没有影响，但宿主性别有影响：雄性蠕虫比雌性蠕虫大 1.8 倍。在 25°C 时，达到易感性的最短时间为 51 天，在 20°C 时为 73 天，尽管在 105 天时，两种温度下仍有一些感染尚未达到易感性。在威尔士，发育最快的感染可能在一个夏季（约 12 周）内成熟，这可能是由于宿主向温暖的地表水移动而加速。否则，10 月至 4 月期间发育速度会减缓/停止，将易感性推迟到感染后约 1 年，而发育速度的广泛差异可能会导致一些原发性感染延迟 2 年，甚至更长时间的继发性感染。
