The Pupal Ectoparasitoid Regulates Cellular and Humoral Immunity of Host .

The immunological interaction between and its larval parasitoids has been thoroughly investigated, however, little is known about the interaction between the host and its pupal parasitoids. , a pupal ectoparasitoid of , injects venom into its host while laying eggs on the puparium, which regulates host immunity and interrupts host development. To resist the invasion of parasitic wasps, various immune defense strategies have been developed in their hosts as a consequence of co-evolution. In this study, we mainly focused on the host immunomodulation by and thoroughly investigated cellular and humoral immune response, including cell adherence, cell viability, hemolymph melanization and the Toll, Imd, and JAK/STAT immune pathways. Our results indicated that venom had a significant inhibitory effect on lamellocyte adherence and induced plasmatocyte cell death. Venom injection and incubation strongly inhibited hemolymph melanization. More in-depth investigation revealed that the Toll and Imd immune pathways were immediately activated upon parasitization, followed by the JAK/STAT pathway, which was activated within the first 24 h post-parasitism. These regulatory effects were further validated by qPCR. Our present study manifested that regulated the cellular and humoral immune system of host in many aspects. These findings lay the groundwork for studying the immunological interaction between and its pupal parasitoid.