Olstad K, Cable J, Robertsen G, Bakke T A
Natural History Museum, Department of Zoology, University of Oslo, P.O. Box 1172, N-0318 Oslo, Norway.
Parasitology. 2006 Jul;133(Pt 1):33-41. doi: 10.1017/S0031182006009966. Epub 2006 Mar 27.
The viviparous monogenean Gyrodactylus salaris continues to devastate Norwegian Atlantic salmon populations despite the extreme measures taken to control this pathogen. Increased understanding of parasite biology is needed to develop alternative control and management strategies of wild Atlantic salmon. We have examined temperature-dependent survival of G. salaris, both on and off the host. At 18 degrees C, survival off the host was 1 day, but at 3 degrees C parasites survived for 4 days. However, in contrast to assumptions made by earlier authors, many parasites remained with their host following its death. Ultrastructural evidence indicated that G. salaris individuals can feed on a dead host, and laboratory tests demonstrated that worms on their hosts more than double their life-span compared with individuals maintained off the host. Experimental infections also demonstrated that establishment and subsequent population growth of parasites previously maintained on dead hosts for 3 days, was similar to that of parasites transferred directly between living hosts. Hence, for G. salaris, dead infected hosts may increase the chances of successful transmission and be a potential important infection source in rivers and hatcheries.
尽管采取了极端措施来控制这种病原体，但胎生单殖吸虫鲑三代虫仍在继续破坏挪威大西洋鲑鱼种群。需要进一步了解寄生虫生物学，以制定野生大西洋鲑鱼的替代控制和管理策略。我们研究了鲑三代虫在宿主上和离开宿主后的温度依赖性存活情况。在18摄氏度时，离开宿主后的存活时间为1天，但在3摄氏度时，寄生虫可存活4天。然而，与早期作者的假设相反，许多寄生虫在宿主死亡后仍与宿主在一起。超微结构证据表明，鲑三代虫个体可以以死亡的宿主为食，实验室测试表明，与离开宿主的个体相比，寄生于宿主上的蠕虫寿命延长了一倍多。实验感染还表明，先前在死亡宿主上存活3天的寄生虫的定殖和随后的种群增长，与直接在活宿主之间转移的寄生虫相似。因此，对于鲑三代虫来说，死亡的受感染宿主可能会增加成功传播的机会，并且可能是河流和孵化场中潜在的重要感染源。
