Detrimental effects on hosts can occur at several stages of the parasite 's life cycle.
Host radiation allows a parasite to expand its ecological niche by adapting to one or more novel hosts.
By contrast, infection will tend to limit nitrate accumulation in the host roots as a result of nitrate transfer from host roots to the parasite .
Because host nestlings remain in the nest, the parasite must compete with host nestlings for food.
The relationship between host and parasite is not a simple one, and just as the parasite affects the host, so the host affects the parasite .
We consider three rejection scenarios by a host of a nonevicting parasite .
These neocon pseudofascists are like a parasite using the host Republican party to attain their ends.
an intestinal parasite of cattle
the parasite attaches itself to the mouths of fishes
Only the latter could be accepted as evidence of coevolution between the parasite and a particular host.