Data from: Inter- and Intraspecific Conflict between Parasites over Host Manipulation

Host manipulation is a common strategy by which parasites alter the behaviour of their host to enhance their own fitness. In nature, hosts are usually infected by multiple parasites. This can result in a conflict over host manipulation. Studies of such a conflict in experimentally infected hosts are rare. The cestode Schistocephalus solidus (S) and the nematode Camallanus lacustris (C) use copepods as their first intermediate host. They need to grow for some time inside this host before they are infective and ready to be trophically transmitted to their subsequent fish host. Accordingly, not yet infective parasites manipulate to suppress predation. Infective ones manipulate to enhance predation. We experimentally infected lab-bred copepods in a manner that resulted in copepods harbouring (1) an infective C plus a not yet infective C or S or (2) an infective S plus a not yet infective C. An infective C completely sabotaged host manipulation by any not yet infective parasite. An infective S partially reduced host manipulation by a not yet infective C. We hence show experimentally that a parasite can reduce or even sabotage host manipulation exerted by a parasite from a different species.宿主操控（host manipulation）是寄生虫为提升自身适配度（fitness），改变宿主行为的常见策略。自然界中，宿主通常会被多种寄生虫感染，这可能引发宿主操控权的冲突。目前针对实验感染宿主中的这类冲突的研究较为匮乏。绦虫（cestode）Schistocephalus solidus（简称S）与线虫（nematode）Camallanus lacustris（简称C）均以桡足类（copepods）作为第一中间宿主（first intermediate host）。二者需在宿主体内生长一段时间，方可具备感染性，进而通过营养传播（trophic transmission）至后续的鱼类宿主。因此，尚未具备感染性的寄生虫会操控宿主以降低被捕食概率，而具备感染性的寄生虫则会操控宿主以提升被捕食概率。本研究以实验方式感染实验室繁育的桡足类，构建了两组感染组合：（1）1株具备感染性的C与1株尚未具备感染性的C或S；（2）1株具备感染性的S与1株尚未具备感染性的C。实验结果显示，具备感染性的C会完全破坏其他尚未具备感染性的寄生虫所实施的宿主操控行为；而具备感染性的S仅会部分削弱尚未具备感染性的C所实施的宿主操控行为。综上，本研究通过实验证实，一种寄生虫可以削弱甚至破坏另一物种寄生虫所实施的宿主操控行为。