Effect of the venom of the gregarious parasitoid Apanteles glomeratus on its hemocytic encapsulation by the host, Pieris

When eggs from the lateral oviduct of the gregarious parasitoid Apanteles glomeratus were injected with calyx fluid and venom apparatus material into host larvae, Pieris rapae crucivora, most of the eggs were not encapsulated. Apanteles eggs deposited by the parasitoid from which the venom apparatus was removed were usually encapsulated by the host. These results indicate that the parasitoid venom apparatus material is an important factor in suppressing the encapsulation of 1- or 2-day-old eggs in the host. In order to clearly demonstrate that the venom suppresses egg encapsulation but not the encapsulation of other foreign objects, DEAE-Sephadex A-50 ion-exchange particles stained with 0.001% (w/v) Congo Red solution were injected into hosts together with venom apparatus material. The Sephadex particles were encapsulated by host hemocytes. The results suggest that the venom does not inhibit the encapsulation ability of the host.