PDF(Pubmed)
Abstract：
The change in the distribution of organisms in freshwater ecosystems due to natural or manmade processes raises the question of the impact of alien species on local communities. Although most studies indicate a negative effect, the positive one is more difficult to discern, especially in multispecies systems, including hosts and parasites. The purpose of the study was to check whether the presence of an alien host, Potamopyrgus antipodarum, reduces the intensity of Echinoparyphium aconiatum metacercariae in a native host, Radix spp. We additionally tested the impact of water temperature and the biomass of the alien host on the dilution effect. We experimentally studied (1) the lifespan of echinostome cercariae in different temperatures, (2) the infectivity of cercariae toward the alien host and native host, and (3) the impact of different biomass of the alien host on the intensity of metacercariae in the native host. We found that cercarial survival and infectivity were temperature dependent. However, cercarial survival decreased with increasing temperature, contrary to cercarial infectivity. Echinostome cercariae entered the renal cavity of both the native host and alien host, and successfully transformed into metacercariae. The number of metacercariae in the native host decreased with the increasing biomass of the alien host. Our results indicate that lymnaeids may benefit from the co-occurrence with P. antipodarum, as the presence of additional hosts of different origins may reduce the prevalence of parasites in native communities. However, the scale of the dilution effect depends not only on the increased spectrum of susceptible hosts but also on the other variables of the environment, including water temperature and host density.
摘要：
由于自然或人为过程，淡水生态系统中生物分布的变化提出了外来物种对当地社区影响的问题。尽管大多数研究表明有负面影响，积极的是更难以辨别，尤其是在多物种系统中，包括宿主和寄生虫。这项研究的目的是检查是否存在外星人宿主，Potamopyrgusanipodarum,降低了本地宿主的棘皮虫的强度，天基。我们还测试了水温和外来宿主的生物量对稀释效果的影响。我们通过实验研究了(1)不同温度下棘皮虫尾蚴的寿命，(2)尾蚴对外源宿主和本地宿主的感染性,（3）外来寄主不同生物量对本地寄主囊虫强度的影响。我们发现，子宫颈的存活和传染性与温度有关。然而,随着温度的升高，子宫颈存活率降低，与子宫颈传染性相反。棘突尾蚴进入天然宿主和外来宿主的肾腔，并成功地转化为尾蚴。随着外来寄主生物量的增加，天然寄主中的囊虫数量减少。我们的结果表明，lymnaeids可能受益于与对侧假单胞菌的共现，由于不同来源的其他宿主的存在可能会降低本地社区中寄生虫的患病率。然而,稀释效应的规模不仅取决于易感宿主的频谱增加，还取决于环境的其他变量，包括水温和宿主密度。
