Comparison of parasitism by Cotesia glomerata with bacterial infection and wounding in Pieris brassicae: induction of new haemolymph polypeptides and changes in humoral immune response

In Pieris brassicae, parasitism by Cotesia glomerata and bacterial infection are differentiated with respect to haemolymph protein arrays, and production or suppression of antibacterial agents. Bacteriolytic activity in haemolymph from parasitized larvae was slightly, but significantly, higher 24h post-treatment than that of untreated and wounded controls. Micrococcus lysodeikticus- or lipopolysaccharide-(LPS) injected insects exhibited an 11-fold greater response than those parasitized. At 24h post-treatment, antibacterial activity against Escherichia coli was observed in haemolymph from all but untreated larvae. Injection of Grace's medium, M. lysodeikticus or LPS, caused a greater than threefold response than parasitization or wounding. The protein banding patterns of parasitized hosts did not correspond to those of the other treatments. Two parasitoid-induced proteins (38 and 128 kDa) were examined. Both were found in parasitized insects, not in those wounded, injected with Grace's medium, M. lysodeikticus or LPS. Neither protein was bacteriolytic or bacteriostatic in inhibition zone assays.