Hermetia illucens (L.) (Diptera: Stratiomyidae) is able to consume a wide range of organic matter and is of particular interest for waste management. The nutritional value of preimaginal stages, in particular the protein content, makes this species a valid candidate for use as feed for other organisms. Vegetables and fruits are promising rearing substrates for insects produced for this purpose according to the EU regulation. In order to examine the effects of diets on insect performance and chemical composition, larvae were reared on the following substrates: 1) fruit (apple, pear, and orange); 2) vegetable (lettuce, green beans, and cabbage); and 3) mixed fruits and vegetables. High percentages of survival were observed on all diets, but there were differences among weights of larvae, pupae, and adults, with weights of larvae reared on mixed fruits and vegetables lower than on other diets. Pupae reared on the mixed diet were heaviest, and also morphometric measurements of adults were highest. Larvae reared on fruit diets had the highest fat content, comprising mostly saturated fatty acids; the highest content of essential n-3 fatty acids was found in vegetable reared larvae and that of n-6 in mixed reared larvae. Larvae reared on the mixed diet had the highest protein content. Calcium contents were high and moderate amounts of iron and zinc were found. H. illucens showed the capability to develop on vegetable and fruits diets displaying different nutrient profiles and biological performances. The best-performing rearing strategy should vary in relation to the final use of H. illucens.

The aim of the study was to evaluate the use of three by-products as growing substrates for Hermetia illucens (Black Soldier Fly (BSF)) larvae: okara, maize distiller, brewer’s grains, and a control hen diet. The study focused on larval growth and bioconversion performance, production of methane by larvae and environmental burden of larvae production, using Life Cycle Assessment (LCA) on a lab scale. Chemical composition of substrates differed: okara had the highest crude protein and ether extract contents, while brewer’s grains showed the highest fiber content. Larvae fed on a hen diet and maize distiller exhibited the highest final weights (2.29 and 1.97 g, respectively). Larvae grown on okara showed the highest indexes for waste reduction and efficiency of conversion of the ingested feed. The BSF larvae did not produce any detectable traces of CH4. LCA evaluation showed that larvae production on a hen diet resulted in the most impact for most of environmental categories, for the inclusion of soybean meal in the diet (for climate change, 5.79 kg CO2 eq/kg dry larvae). Feed production activities resulted in the main contributions to environmental impact. In order to compare the larvae production obtained on all substrates, an environmental impact was attributed to okara and brewer’s grain through a substitution method, and, by this approach, the best sustainable product resulted from the larvae grown on the maize distiller.

The worldwide growing consumption of proteins to feed humans and animals has drawn a considerable amount of attention to insect rearing. Insects reared on organic wastes and used as feed for monogastric animals can reduce the environmental impact and increase the sustainability of meat/fish production. In this study, we designed an environmentally closed loop for food supply in which fruit and vegetable waste from markets became rearing substrate for Hermetia illucens (BSF— black soldier fly). A vegetable and fruit-based substrate was compared to a standard diet for Diptera in terms of larval growth, waste reduction index, and overall substrate degradation. Morphological analysis of insect organs was carried out to obtain indications about insect health. Processing steps such as drying and oil extraction from BSF were investigated. Nutritional and microbiological analyses confirmed the good quality of insects and meal. The meal was then used to produce fish feed and its suitability to this purpose was assessed using trout. Earthworms were grown on leftovers of BSF rearing in comparison to a standard substrate. Chemical analyses of vermicompost were performed. The present research demonstrates that insects can be used to reduce organic waste, increasing at the same time the sustainability of aquaculture and creating interesting by-products through the linked bio-system establishment.

Larvae of the black soldier fly (BSF) Hermetia illucens (L.) convert organic waste into high valuable insect biomass that can be used as alternative protein source for animal nutrition or as feedstock for biodiesel production. Since insect biology and physiology are influenced by the gut microbiome, knowledge about the functional role of BSFassociated microorganisms could be exploited to enhance the insect performance and growth. Although an increasing number of culture-independent studies are unveiling the microbiota structure and composition of the BSF gut microbiota, a knowledge gap remains on the experimental validation of the contribution of the microorganisms to the insect growth and development. We aimed at assessing if BSF gut-associated bacteria potentially involved in the breakdown of diet components are able to improve host nutrition. A total of 193 bacterial strains were obtained from guts of BSF larvae reared on a nutritious diet using selective and enrichment media. Most of the bacterial isolates are typically found in the insect gut, with major representatives belonging to the Gammaproteobacteria and Bacilli classes. The hydrolytic profile of the bacterial collection was assessed on compounds typically present in the diet. Finally, we tested the hypothesis that the addition to a nutritionally poor diet of the two isolates Bacillus licheniformis HI169 and Stenotrophomonas maltophilia HI121, selected for their complementary metabolic activities, could enhance BSF growth. B. licheniformis HI169 positively influenced the larval final weight and growth rate when compared to the control. Conversely, the addition of S. maltophilia HI121 to the nutritionally poor diet did not result in a growth enhancement in terms of larval weight and pupal weight and length in comparison to the control, whereas the combination of the two strains positively affected the larval final weight and the pupal weight and length. In conclusion, we isolated BSF-associated bacterial strains with potential positive properties for the host nutrition and we showed that selected isolates may enhance BSF growth, suggesting the importance to evaluate the effect of the bacterial administration on the insect performance.

Spinosyns are a class of insecticides with a broad range of action against many insect pests belonging to different orders, noxious to a wide variety of agricultural crops; spinosyns were also used against insects of sanitary interest. Spinosyns are derivative of biological active substances produced by soil Actinomycete Saccharopolyspora spinosa; being of biological origin, they are considered to have a low environmental impact and they are not much aggressive against nontarget species. They act as allosteric activators of nicotinic acetylcholine receptors; thanks to their mode of action the resistance phenomena are uncommon, even few cases of resistance were recently reported.For all these reasons at present they are one of the most interesting product to be used in fighting against agriculture pests.