Am Nat. 2020 Aug;196(2):119-131. doi: 10.1086/709163. Epub 2020 Jun 10.
Dispersal determines the spatial dynamics of host-parasite assemblages, particularly during invasions and disease epidemics. The risk of parasitism may create an incentive for dispersal, but infection is expected to reduce dispersal ability, which may alter the host's dispersal response to biotic stressors, including population density. We measured the dispersal of a semiaquatic insect () in aquatic mesocosms in which we manipulated the presence of ectoparasitic Hydrachnidia mites and infected conspecifics. We found that parasitism risk increases host dispersal propensity. Using a flight assay, we determined that parasite infection reduces host dispersal ability. Finally, we used a mark-release-recapture study to investigate the joint effects of both parasitism risk and parasite infection on host dispersal in a natural, spatially structured population. We found that parasitism risk reduced dispersal probability, eliminated positive density-dependent dispersal, and increased dispersal distance. Infection had no effect on dispersal in the natural population. Our results show that parasites can both increase and decrease the movement rates of their hosts, depending on the ecological context, and can alter the host's dispersal response to other biotic stressors. Future studies should consider the consequences of this double-headed impact of parasites for landscape connectivity, population persistence, and host-parasite coevolution.
扩散决定了宿主-寄生虫组合的空间动态，特别是在入侵和疾病流行期间。寄生虫感染的风险可能会促使宿主扩散，但感染预计会降低扩散能力，这可能会改变宿主对包括种群密度在内的生物胁迫的扩散反应。我们在水生中观中测量了半水生昆虫（）的扩散，在这些中观中，我们操纵了外寄生的 Hydrachnidia 螨虫和感染的同种个体的存在。我们发现，寄生虫感染风险会增加宿主的扩散倾向。使用飞行试验，我们确定寄生虫感染会降低宿主的扩散能力。最后，我们使用标记释放-捕获研究调查了在自然的、空间结构的种群中，寄生虫感染风险和寄生虫感染对宿主扩散的联合影响。我们发现寄生虫感染风险降低了扩散的概率，消除了正密度依赖的扩散，并且增加了扩散距离。感染对自然种群的扩散没有影响。我们的结果表明，寄生虫可以根据生态背景增加或减少其宿主的迁移率，并可以改变宿主对其他生物胁迫的扩散反应。未来的研究应该考虑寄生虫的这种双重影响对景观连通性、种群持久性和宿主-寄生虫共同进化的后果。
