EFFECT OF THE ENTOMOPATHOGENIC FUNGUS BEAUVERIA-BASSIANA ON THE HUMORAL IMMUNE-RESPONSE OF GALLERIA-MELLONELLA LARVAE (LEPIDOPTERA, PYRALIDAE)

In this study the entomopathogen Beauveria bassiana caused no humoral immune response in Galleria mellonella when it entered the host throug h the integument in a natural manner. Initiation of my cosis by inject ion of living or heat-inactivated blastospores elicited the release of antimicrobial proteins such as lysozyme and cecropins within the hemo lymph. Maximum levels were reached 24 h after treatment. Afterwards, t hese levels declined faster in larvae with established mycosis. Subseq uent studies documented the ability of B. bassiana to suppress increas es in antibacterial activity within the hemolymph of G. mellonella lar vae that were pretreated with injections of microbial provocators. The latter induced non-specific de novo synthesis and subsequent release of several proteins within the hemolymph. The protein synthesis of dis eased larvae was not generally affected, even when the larvae were mor ibund. Among the proteins synthesised during the humoral response, onl y certain proteins such as lysozyme were suppressed, as detected by SD S-PAGE and autoradiography. Tile effects of B. bassiana upon the humor al immune response of G. mellonella are discussed in regards to other parasites such as nematodes or Hymenoptera, which reportedly suppress the synthesis of endogenous host proteins.