One of two species of host on which some pathogens, such as certain rust fungi, must develop to complete their life cycles.交替宿主：两种宿主中的一种，某些病原体，如锈真菌要在宿主中生存并结束生命循环
A species of host other than the principal host on which a parasite can survive.转移宿主：一种宿主，但不是寄生虫赖以存活的主要宿主