Parasites
are organisms that grow or feed in or on a "host" organism without providing
any benefit to the host. In nature, tiny wasps of thePolistes family
puncture the skin of Manduca larvae and lay their eggs. When the eggs hatch,
the wasp larvae burrow back out through the skin and attach themselves to
the caterpillar. There, they "hitch a ride", feeding off the Manduca larva
until they reach adulthood.
The important feature of this parasitic relationship is that the Manduca
larvae's normally strong
immune system fails to notice that it has been invaded.Researchers have
found that, along with the eggs, the wasp injects a virus that interferes
with the Manducas immune response. These wasps are already used in agriculture
as a part of integrated pest management, for controlling the plant-munching
Manduca.
Scientists are trying to better understand the biochemical process by which
the virus works, in hopes of using this knowledge to develop better and
safer pest control techniques, and more effective treatments of immune system
disorders in humans.