Relationships between parasitoid Hymenoptera and the immune system of their hosts: The active and passive mechanisms redefined.

Hymenopteran parasitoids developed various strategies for the survival of their offspring at the expense of a generally limited range of insect hosts. Such a diversity suggests the existence of original strategies of virulence for almost each host-parasitoids system. In the field of host development-parasitoids interactions, it is often admitted that parasitic strategies split in two categories, depending on the ability of the parasitoid to conform to host physiology or to regulate it. We propose to define in a similar view parasitoids strategies interacting with hosts immune system, up to now qualified as <> or <>, as strategies of <> or <>. Indeed, recent studies dedicated to particular mechanisms of hosts immune system avoidance (ectoparasitism, molecular <>) shade light on their <> nature and could open a new area in the understanding of their molecular basis. The aim of this report is to underline, through a new descriptive approach, the diversity of ways used by parasitoid Hymenoptera to counteract their hosts immune system. We will: i) summarize the literature related to parasitoids strategies to conform to hosts immune response or to regulate it; ii) examine their underlying physiological factors; and iii) present the main research outlook enable by the studying of such strategies of virulence.