Melanin properties at the different stages towards life cycle of the fly Hermetia illucens

Abstract

<p>Eumelanin type pigments are synthesized at all the stages of the life cycle of the fly Hermetia illucens: in the larvae, pre-pupae,<br />pupae and adult flies (dead flies). The greatest content of melanin was recorded in the cuticles. Melanin was present not only<br />in the cuticle, hence it remained in the cuticle after the emergence of the adult fly. It was also found in the insect body in a<br />complex with lipids. In pupae, it is mostly lauric acid that was associated with melanin. Its proportion in the melanin-chitosan<br />complex was 80%. The isolated melanin-chitosan complex of adult flies showed a wide range of antibacterial activity, inhibiting<br />the growth of 21 out of the 25 of the test cultures. The melanin-chitosan complex of empty pupal membranes and alcohol<br />suspension of pupal melanin inhibited twice as smaller number of test cultures and the above activity was absolutely in the<br />pupal chitosan. The largest zone of growth inhibition was recorded with respect to Aspergillus niger, Candida albicans,<br />salmonella, and Staphylococcus aureus. An alcohol suspension of pupal melanin inhibited the growth of 10 test cultures. In this<br />case the greatest activity was shown in relation to Mycobacterium B5 and Acinetobacter sp. 1182.</p>