Tao Leiling, Gowler Camden D, Ahmad Aamina, Hunter Mark D, de Roode Jacobus C
Department of Biology, Emory University, 1510 Clifton Road, Atlanta, GA 30322, USA
Department of Biology, Emory University, 1510 Clifton Road, Atlanta, GA 30322, USA Department of Ecology and Evolutionary Biology, University of Michigan, 830 N University, Ann Arbor, MI 48109, USA.
Proc Biol Sci. 2015 Oct 22;282(1817):20151993. doi: 10.1098/rspb.2015.1993.
Host-parasite interactions are subject to strong trait-mediated indirect effects from other species. However, it remains unexplored whether such indirect effects may occur across soil boundaries and connect spatially isolated organisms. Here, we demonstrate that, by changing plant (milkweed Asclepias sp.) traits, arbuscular mycorrhizal fungi (AMF) significantly affect interactions between a herbivore (the monarch butterfly Danaus plexippus) and its protozoan parasite (Ophryocystis elektroscirrha), which represents an interaction across four biological kingdoms. In our experiment, AMF affected parasite virulence, host resistance and host tolerance to the parasite. These effects were dependent on both the density of AMF and the identity of milkweed species: AMF indirectly increased disease in monarchs reared on some species, while alleviating disease in monarchs reared on other species. The species-specificity was driven largely by the effects of AMF on both plant primary (phosphorus) and secondary (cardenolides; toxins in milkweeds) traits. Our study demonstrates that trait-mediated indirect effects in disease ecology are extensive, such that below-ground interactions between AMF and plant roots can alter host-parasite interactions above ground. In general, soil biota may play an underappreciated role in the ecology of many terrestrial host-parasite systems.
宿主 - 寄生虫的相互作用会受到来自其他物种的强烈性状介导的间接影响。然而，这种间接影响是否会跨越土壤边界并连接空间隔离的生物体，仍有待探索。在这里，我们证明，丛枝菌根真菌（AMF）通过改变植物（马利筋属Asclepias sp.）的性状，显著影响了一种食草动物（黑脉金斑蝶Danaus plexippus）与其原生动物寄生虫（微孢子虫Ophryocystis elektroscirrha）之间的相互作用，这代表了一种跨越四个生物界的相互作用。在我们的实验中，AMF影响了寄生虫的毒力、宿主的抗性以及宿主对寄生虫的耐受性。这些影响既取决于AMF的密度，也取决于马利筋物种的身份：AMF间接增加了在某些物种上饲养的黑脉金斑蝶的疾病发生率，同时减轻了在其他物种上饲养的黑脉金斑蝶的疾病发生率。物种特异性在很大程度上是由AMF对植物初级（磷）和次级（强心甾；马利筋中的毒素）性状的影响驱动的。我们的研究表明，疾病生态学中由性状介导的间接影响是广泛存在的，以至于AMF与植物根系之间的地下相互作用可以改变地上的宿主 - 寄生虫相互作用。一般来说，土壤生物群落在许多陆地宿主 - 寄生虫系统的生态学中可能发挥着未被充分认识的作用。
