Schjetlein J, Skorping A
Department of Ecology/Zoology, IBG, University of Tromsø, Norway.
Parasitology. 1995 Jul;111 ( Pt 1):103-10. doi: 10.1017/s0031182000064659.
To test the hypothesis that the relatively high developmental temperature threshold of the parasitic nematode Elaphostrongylus rangiferi in the intermediate snail host is an adaptation to minimize larval mortality during winter, an experiment was set up in which snails of the species Arianta arbustorum were experimentally infected with the parasite. The snails were divided into 3 groups known to contain 1st, 2nd or 3rd-stage larvae, and incubated at 3 degrees C for an experimental period of 18 weeks. First-stage larvae showed a significantly higher survival rate within snails than 2nd or 3rd-stage larvae. We also found that snails carrying 1st-stage larvae survived better than snails with other larval stages. It is concluded that if the nematode has started development before the hibernation, this has a real and significant effect on the risk of dying. The high developmental threshold is therefore likely to be an adaptation to reduce the chance of hibernating as developing larvae during long periods of low temperatures.
为了验证寄生线虫驯鹿后圆线虫在中间宿主蜗牛体内相对较高的发育温度阈值是一种为尽量减少冬季幼虫死亡率的适应性特征这一假设，开展了一项实验，用该寄生虫对庭园蜗牛进行实验性感染。蜗牛被分为已知含有第1、2或3期幼虫的3组，并在3摄氏度下孵育18周的实验期。第1期幼虫在蜗牛体内的存活率显著高于第2或3期幼虫。我们还发现，携带第1期幼虫的蜗牛比携带其他幼虫期的蜗牛存活得更好。得出的结论是，如果线虫在冬眠前就已开始发育，这对死亡风险具有切实且显著的影响。因此，较高的发育阈值很可能是一种适应性特征，以减少在长时间低温期间作为发育中幼虫进入冬眠的机会。
