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Parasitoids
Most parasitoids — parasitic insects that kill their hosts
— live freely and independently as adults; they are lethal
and dependent only in their immature stages. Parasitoids can be
specialists, targeting either a single host species or several related
species, or they can be generalists, attacking many types of hosts.
Typically, they attack hosts larger than themselves, eating most
or all of their hosts’ bodies before pupating inside or outside
them.
When the parasitoid emerges from its pupa as an adult, it usually
nourishes itself on honeydew, nectar or pollen — although
some adults make meals of their host’s body fluids and others
require additional water. Adult female parasitoids quickly seek
out more victims in which to lay their host-killing eggs. With their
uncanny ability to locate even sparsely populated hosts using chemical
cues, parasitoid adults are much more efficient than predators at
ferreting out their quarry.
Different parasitoids can victimize different life stages of the
same host, although specific parasitoids usually limit themselves
to one stage. Thus, parasitoids are classified as egg parasitoids,
larval (nymphal) parasitoids or adult parasitoids. Some parasitoids
lay their eggs in one life stage of a victim but emerge at a later
life stage. Parasitoids are also classified as either ectoparasites
or endoparasites depending, respectively, on whether they feed externally
on their hosts or develop inside them. Their life cycle is commonly
short, ranging from 10 days to four weeks.
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