Specialist by preference, generalist by need: availability of quality
hosts drives parasite choice in a natural multihost-parasite system
Abstract
Encountering suitable hosts is key for parasite success. In a natural
system involving a parasitic fly and its multiple bird hosts there are
profound differences in host quality. The Great Kiskadee tolerates and
does not invest in resisting the infection, which makes it an optimal
host. Alternative hosts are frequently used, but whilst some of them may
be good options, others are bad alternatives (they resist efficiently or
die). Here we examined the host selection processes that drive parasite
dynamics in this system with a thorough longitudinal study under natural
conditions. We found that host selection is strongly driven by
availability of quality hosts: the parasite chooses suboptimal hosts
only when better alternatives are not sufficiently available. This adds
evidence from a natural system that hosts are chosen as a function of
their profitability, and shows that host selection by a parasite may be
plastic and context-dependent.