van Dijk J, Morgan E R
School of Biological Sciences, University of Bristol, Bristol, UK.
J Helminthol. 2012 Sep;86(3):287-92. doi: 10.1017/S0022149X1100040X. Epub 2011 Jul 26.
This paper examines the influence of water on the ecology of the eggs of Nematodirus battus, with a view to estimating the importance of including rainfall in mathematical models of parasite abundance. The literature suggests that, under pasture conditions, the availability of moisture is unlikely to be limiting for egg development, while eggs and infective larvae are highly resistant to desiccation. In the presented experiment, eggs that had been kept in salt sludges at 95% and 70% RH and were subsequently put at 15°C produced only a mildly accelerated, but not a mass, hatch, in the first few days after return to water. Eggs kept at higher osmotic pressures died. Mass hatching of infective larvae, described at pasture when spells of rain follow periods of drought, is unlikely to occur as the result of a sudden water influx into eggs. Since water is not necessary for migration of infective larvae from the soil on to grass, such peaks in larval abundance are more likely to arise from the effects of temperature on hatching of eggs.
本文研究了水分对巴氏细颈线虫虫卵生态学的影响，旨在评估在寄生虫丰度数学模型中纳入降雨的重要性。文献表明，在牧场条件下，水分的可利用性不太可能限制虫卵发育，而虫卵和感染性幼虫对干燥具有高度抗性。在本实验中，置于相对湿度95%和70%的盐泥中、随后置于15°C环境下的虫卵，在重新接触水后的头几天，孵化仅略有加速，但并未大量孵化。处于较高渗透压下的虫卵死亡。在牧场中，干旱期后降雨时出现的感染性幼虫大量孵化，不太可能是由于水分突然进入虫卵所致。由于水分对于感染性幼虫从土壤迁移到草上并非必需，幼虫丰度的此类峰值更可能是温度对虫卵孵化的影响所致。
