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

Abstract

Eumelanin type pigments are synthesized at all the stages of the life cycle of the fly Hermetia illucens: in the larvae, pre-pupae, pupae and adult flies (dead flies). The greatest content of melanin was recorded in the cuticles. Melanin was present not only 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 complex with lipids. In pupae, it is mostly lauric acid that was associated with melanin. Its proportion in the melanin-chitosan complex was 80%. The isolated melanin-chitosan complex of adult flies showed a wide range of antibacterial activity, inhibiting the growth of 21 out of the 25 of the test cultures. The melanin-chitosan complex of empty pupal membranes and alcohol suspension of pupal melanin inhibited twice as smaller number of test cultures and the above activity was absolutely in the pupal chitosan. The largest zone of growth inhibition was recorded with respect to Aspergillus niger, Candida albicans, salmonella, and Staphylococcus aureus. An alcohol suspension of pupal melanin inhibited the growth of 10 test cultures. In this case the greatest activity was shown in relation to Mycobacterium B5 and Acinetobacter sp. 1182.Key words: melanin; melanin-chitosan complex; Hermetia illucens; antibacterial activityThe fly Hermetia illucens is a typical member of Stratiomyidae, Diptera, Insecta (Linnaeus, 1758) is characterized by complete metamorphosis, including the main developmental stages as the egg, larva, pre-pupae, pupae, adult individual. It is only larvae that feed. Larvae are able to recycle different organic waste, using them as foraging substrates. This property determines the increased interest in these insects and the peculiarities of their biochemical composition in connection with the prospects of using insect meal in feed and food (. Although the chemical composition of the insect larvae varies with food substrate the fat content averages 30% (Diener, et al., 2011;St-Hilaire, et al., 2007;Gobbi, et al., 2013;Kalová, Borkovcová, 2013). Adult flies are equally fat. Our data demonstrate that fat content in dead flies accounts for 27%, and that in the larvae raised on wheat grains, 38%, and in prepupae, 32%. The large amount of fat in the body of the fly necessitates its antioxidant protection, which may be provided by melanin pigments. Melanins are nitrogen-containing compounds of irregular structure on the basis of phenol, which are the main pigment of insects. They create the dark-brown or brown coloration of insects, being created by the insects themselves, and become part of the cuticle, are present in the hemolymph, adipose body, and the intestinal tract (Nicolaus, 1968;Prota, 1992). The pigments have antioxidant, radio-and photo-protector, electron and ion-exchange properties (Dontsov, 2014;Ostrovsky, Dontsov, 1985). Natural melanin pigments show antibacterial and immune-modulation activity. They can form diverse complexes with proteins, various pharmacological agents, for instance, with antibiotics, which i...

Effect of Black Soldier Fly (Hermetia illucens L.) Fat on Health and Productivity Performance of Dairy Cows

“…The presence of melanin may also contribute to long-term storage [ 41 ]. In earlier studies, we found that, in the suspension prepared for testing from BSFL, the concentration of melanin was 1.2 mg/mL [ 22 ]. There are also reports on the anti-stress effect of melanin [ 42 ]: when it was added to the diet of animals (0.1 mg/kg) no cases of disease were observed; it was shown [ 43 ] that, in stressed animals, melanin promotes the normalization of proteinase-inhibitory potential and prevents the development of pancreatic cytolytic syndrome.…”

“…Thus, larvae, pre-pupae, pupae, and adult flies of Hermetia illucens contain eumelanin-type pigments, which are present not only in the cuticle but also in the insect body in complex with lipids. In larvae, this is mainly lauric acid, which is associated with a melanin–chitosan complex with a wide spectrum of antibacterial activity against Aspergillus niger , Candida albicans, Salmonella and Staphylococcus aureus [ 22 , 23 , 24 ].…”

Insects as food and feed, a new emerging agricultural sector: a review

“…The maximum melanin content was detected in the pupae, while the synthesis was most observed at the prepupa stage. In pupae, it is mostly associated with lauric acid with a proportion of 80% in melanin-chitosan complex (Ushakova et al, 2017).…”

Black Soldier Fly (Hermetia illucens) Larvae as an Ecological, Immune Booster and Economical Feedstuff for Aquaculture

“…A phenolic compound, melanin, is a bio-active component that is used as a feed additive to prevent stress and tumors in farmed animals (Cordero & Casadevall, 2020). Melanin that imparts black color to black soldier fly is eumelanin and it has a wide range of antibacterial and antifungal action (Ushakova et al, 2017). In a study, the extract of BSF larvae was evaluated for antibacterial action by the agar diffusion method.…”