Hemiparasites can transmit indirect effects from their host plants to herbivores

Parasitic plants can serve as critical intermediaries between their hosts and other organisms; however these relationships are not well understood. To investigate the relative importance of plant traits in such interactions, we studied the role of the root hemiparasite, Castilleja levisecta (Orobanchaceae), as a mediator of interactions between the host plants it parasitizes and the lepidopteran herbivore Euphydryas editha (Nymphalidae), whose caterpillars feed on Castilleja and sequester iridoid glycosides from it. We tested whether the hemiparasite’s size, leaf N concentration, and iridoid glycoside concentrations were influenced by the identity of its host plant, and then whether these traits influenced outcomes for the herbivore. We found that the hemiparasite’s size and leaf N depended on the host it parasitized, and these traits in turn affected outcomes for E. editha. Specifically, Euphydryas editha survival increased with hemiparasite size and caterpillar mass increased with le...

寄生植物可作为其寄主与其他生物间的关键中介，但此类物种关联的相关机制尚未得到充分解析。为探究植物性状在这类互作中的相对重要性，本研究以根半寄生植物亮黄火焰草（Castilleja levisecta，列当科Orobanchaceae）为研究对象，考察其作为被寄生寄主与鳞翅目食草昆虫伊迪丝蛱蝶（Euphydryas editha，蛱蝶科Nymphalidae）之间互作的中介作用——该蝶幼虫以该半寄生植物为食，并从其体内蓄积环烯醚萜苷（iridoid glycosides）。
我们首先验证了该半寄生植物的株高、叶片氮浓度以及环烯醚萜苷浓度是否受其寄主种类的调控，随后进一步探究这些性状是否会对该食草昆虫的生存适合度产生影响。研究结果表明，该半寄生植物的株高与叶片氮浓度确实依赖于其所寄生的寄主种类，而这些性状又会反过来影响伊迪丝蛱蝶的生存状况。具体而言，伊迪丝蛱蝶的存活率随半寄生植物株高的增加而升高，幼虫体重随……