The role of the foreign surface and female parasitoid secretions on the immune response of an insect

Most successful parasitoids are able to avoid the encapsulation reaction of their host. A similar avoidance was observed with particles of a weakly acidic cation exchanger which was not encapsulated following its injection into the haemocoele of an insect. The ionic nature of the surface of the acidic cation exchanger and the two species of parasitoid eggs appeared to be similar. A weakly basic anion exchanger was readily encapsulated following injections into the haemocoele of a host. The encapsulation of the basic anion exchanger was prevented by coating the surface with fluid from the calyx region of the female parasitoid ovary. The importance of the fluid from the calyx region of the parasitoid and the ionic nature of the surface in avoiding the encapsulation reaction of the hosts haemocytes is discussed.