As a major lignocellulosic biomass, which represented more than half of the world’s agricultural phytomass, crop residues have been considered as feedstock for biofuel production. However, large-scale application of this conventional biofuel process has been facing obstacles from cost efficiency, pretreatment procedure, and secondary pollution. To meet the growing demands for food, feed, and energy as the global population continues to grow, certain kinds of insects, many of which are voracious feeders of organic wastes that may help address environmental, economic, and health issues, have been highlighted as a source of protein and fat. The biorefinery studied includes initial corn stover degradation by yellow mealworm (Tenebrio molitor L.), followed by a second stage that employs black soldier fly (Hermetia illucens L.), to utilize the residues produced during the first stage. These two insect-based biorefinery yielded 8.50 g of insect biomass with a waste dry mass reduction rate of 51.32%, which resulted in 1.95 g crude grease from larval biomass that produced 1.76 g biodiesel, 6.55 g protein, and 111.59 g biofertilizer. The conversion rate of free fatty acids of crude grease into biodiesel reached 90%. The components of cellulose, hemicellulose, and lignin contained in corn stover hydrolyzed harmoniously, resulting in declines of 45.69, 51.85, and 58.35%, respectively. Moreover, fluctuations in lipid, protein, and reducing sugar were also analyzed. The investigation findings demonstrated that successive co-conversion of corn stover by insects possessing different feeding habits could be an attractive option for efficient utilization of lignocellulosic resources, and represents a potentially valuable solution to crop residues management, rise of global liquid energy, and animal feed demand.

Chitin and chitosan are biopolymers that are frequently found in nature and have a broad range of applications in the food, biomedical and industrial sectors, due to their high biological activity. The primary source of chitin and chitosan is shellfish, however, shortages in the supply chain, seasonality issues in their availability, as well as ecological degradation are only a few of the problems with the main chitin resources. Due to the broad spectrum of applications for which chitin can be used, the demand for chitin and its derivatives is increasing. Therefore, the market is looking for widely available, greener alternatives to the main commercial chitin sources. Insects appear as a suitable candidate to fill this gap. During insect rearing and processing, a number of side streams are generated, e.g., exuviae of larvae and pupae, dead adults, etc. which are currently mostly discarded as waste. However, these side streams could constitute a novel and long-term supply of chitin for industrial applications. Recent research has demonstrated the suitability of several edible insect species for the production of chitin and chitosan, wherein the exoskeleton of the black soldier fly and field cricket are rich in chitin, making them a good source for chitin and chitosan extraction and purification among other farmed insect candidates. Moreover, several potential uses have been identified for insect-derived chitin and chitosan. Thus, this review aims to present recent advances in the production of chitin and chitosan from edible insects, specifically on their extraction and purification, as well as on their applications for agriculture, food and nutrition, biomedicine and bioplastic production.

Summary: The potential utility of black soldier fly larvae (BSFL) to convert animal waste into harvested protein or lipid sources for feeding animal or producing biodiesel provides a new strategy for agricultural waste management. In this study, the taxonomic structure and potential metabolic and nutrient functions of the intestinal bacterial communities of BSFL were investigated in chicken and swine manure conversion systems. Proteobacteria, Firmicutes and Bacteroidetes were the dominant phyla in the BSFL gut in both the swine and chicken manure systems. After the larvae were fed manure, the proportion of Proteobacteria in their gut significantly decreased, while that of Bacteroidetes remarkably increased. Compared with the original intestinal bacterial community, approximately 90 and 109 new genera were observed in the BSFL gut during chicken and swine manure conversion, and at least half of the initial intestinal genera found remained in the gut during manure conversion. This result may be due to the presence of specialized crypts or paunches that promote microbial persistence and bacteria–host interactions. Ten core genera were found in all 21 samples, and the top three phyla among all of the communities in terms of relative abundance were Proteobacteria, Firmicutes and Bacteroidetes . The nutrient elements (OM, TN, TP, TK and CF) of manure may partly affect the succession of gut bacterial communities with one another, while TN and CF are strongly positively correlated with the relative abundance of Providencia . Some bacterial taxa with the reported ability to synthesize amino acids, Rhizobiales , Burkholderia , Bacteroidales, etc ., were also observed in the BSFL gut. Functional analysis based on genes showed that intestinal microbes potentially contribute to the nutrition of BSFL and the high‐level amino acid metabolism may partly explain the biological mechanisms of protein accumulation in the BSFL body. These results are helpful in understanding the biological mechanisms of high‐efficiency nutrient conversion in BSFL associated with intestinal microbes.

Black soldier fly (BSF) larvae are often exposed to organic waste which harbors abundant zoonotic pathogens. We investigated the ability of BSF larvae to inhibit the zoonotic pathogens naturally found in pig manure. The zoonotic pathogens populations were detected by using selective medium during the conversion. Results showed that the viability of the zoonotic pathogens in pig manure was significantly affected. After eight days of conversion, the Coliform populations were undetected, and Staphylococcus aureus and Salmonella spp. decreased significantly on the eighth day. Antimicrobial assays of the purified recombinant defensin-like peptide 4 (DLP4) showed that this peptide exhibits inhibitory activity against S. aureus, Salmonella enterica serovar typhimurium, and Escherichia coli in vitro. Bacteria BSF-CL and BSF-F were isolated from the larvae gut, and both inhibited the growth of S. aureus and E. coli, but Salmonella spp. was sensitive to the BSF-CL strain (but not to the BSF-F strain). The results from our experiments indicate that BSF larvae are capable of functionally inhibiting potential zoonotic pathogens in pig manure through a variety of mechanisms including antimicrobial peptides expression and the gut associate microorganisms. This study provides a theoretical basis for further study on the combined mechanism of BSF larvae immunity and its gut microbes against the zoonotic pathogens in pig manure.