定义：A group of species that exploit the same food resources, and/or use the same feeding or foraging methods. http://en.wikipedia.org/wiki/Guild_(ecology)
定义：A heterotroph with a temporary parasitic association with another organism that leads to the death of the host. After which, the parasitoid can continue without the host or can move on to a new host. These organisms are considered partly parasites and partly predators.
