Antimicrobial activities in the haemolymph ofPhlebotomus papatasi(Diptera, Psychodidae)

Aspects of the humoral immune response in larvae and adults of sand fly Phlebotomus papatasi were investigated by means of antimicrobial and enzymatic assays. Anti‐Gram‐negative bacteria (Escherichia coli LE 392) activity was detected in the haemolymph of 10‐day‐old adult sand flies, whereas it was not observed in that of either younger (5‐day‐old) adults or larvae. An intense lysozyme‐like activity against killed Gram‐positive bacteria (Micrococcus luteus) was observed in the haemolymph of larvae and in adult sand flies, being more intense in aged insects (10‐day—old) than in younger ones (5‐day‐old). The presence of phenoloxidase activity, responsible for melanization and micro‐organism encapsulation, was demonstrated in the haemolymph of four instar larvae and was monitored until the enzyme reached a plateau.