Lysozyme activity in hemolymph of larvae and pupae of Spodoptera frugiperda (Lepidoptera: Noctuidae)

Abstract

Lysozyme is a bacteriolytic enzyme widely distributed among living organisms. The determination of its activity using turbidimetric methods, consisting in measuring of lysis of Microccocus luteus by the enzyme, has given dissimilar results in previous comparative studies. The lysozyme activity (AL) was measured using this method in the hemolymph (HL) of larvae and pupae of the plague species Spodoptera frugiperda, in order to quantify it and in order to dertermine the existing relation between concentration and activity. Dilutions of HL samples (12.5; 25 and 50 %) were used. Results showed that in both larvae and pupae, the least diluted samples produced greater lytic activity, although it was lower than expected starting at the tested concentration. Moreover specific lytic activities (AL/uL HL) as a function of the absolute quantity of lysozyme present were greater in the more diluted samples. Readings taken at specified intervals did not have a direct relation on the concentration either, these readings in HL of larvae and pupae being similar. It is noted that the activity of HL has greater duration in assays when compared to what has been observed in mammalian milk.