Strategies of avoidance of host immune defenses in Asobara species.

Eggs and larvae of endophagous parasitoids face the host's immunity reaction once they penetrate the insect host's hemocele. In order to overcome the host's immune barrier, endoparasitoids have developed various strategies. Conformer parasitoids hide and/or get protected from the attack by the host's immunity cells without interfering with the host's immune system. Differently, regulator parasitoids directly attack the host's hemocytes, therefore totally inhibiting the immunity reaction of encapsulation in the parasitized host. Female wasps may also discriminate immunoreactive hosts from nonreactive, permissive ones before laying an egg. These different strategies coexist within the same genus of the braconids Asobara, endoparasitoids of Drosophila larvae. The physiological mechanisms underlying the conformer and regulator strategies in Asobara are exposed. The factors which may contribute to the diversity of the means developed by Asobara parasitoids to overcome the hosts' immunity defenses are discussed.