Review of Black Soldier Fly (Hermetia illucens) as Animal Feed and Human Food

The defatted black soldier fly meal (Hermetia illucens) improved the pathogen resistance and gut health of Nile Tilapia (Oreochromis niloticus)

As a novel protein source, the black soldier fly (Hermetia illucens) possesses the potential to enhance fish health due to its high protein content, essential amino acids, and bioactive compounds, but the mechanisms by which defatted black soldier fly meal affects fish health remain unclear. This study aimed to evaluate the effects of partially replacing soybean meal (SM) with defatted black soldier fly larvae meal on the pathogen resistance of juvenile Nile tilapia (Oreochromis niloticus) and to explore the underlying mechanisms. Defatted black soldier fly (Hermetia illucens) meal was used to replace 0 % (CON), 15 % (H15), 30 % (H30), 45 % (H45), and 60 % (H60) of soybean meal in the diets, which were fed to Nile tilapia for 8 weeks. At the second week of the experiment, an unexpected infection was observed in the Nile tilapia, with subsequent isolation and identification confirming the pathogen as Aeromonas veronii. The results showed that defatted black soldier fly meal improved the survival rate and reduced the intestinal inflammation of Nile tilapia in H60 group compared to CON group (P < 0.05). Periodic acid-Schiff (PAS) staining of the gut indicated that a 60 % replacement of soybean meal with defatted black soldier fly meal significantly increased the number of goblet cells in the intestine (P < 0.05) and upregulated the expression level of mucin 2 (muc2) (P < 0.05). Throughout the experiment period, the survival rate in the defatted black soldier fly meal groups was higher than that in the soybean meal group, with the H60 group exhibiting the most significant improvement. In addition, defatted black soldier fly meal exhibited a promotion effect on goblet cell numbers, mucin production and mucin secretion with a dose dependent manner (P < 0.05). To identify the possible mechanism by which defatted black soldier fly meal enhanced goblet cell numbers, gut microbiome and metabolomics were conducted. The results showed that the defatted black soldier fly meal altered the composition of intestinal microbiota and increased the content of L-tyrosine in the H60 group. The effects of L-tyrosine were further identified in LS174T cells, and the results showed that L-tyrosine upregulated the expression levels of muc2 and SAM pointed domain-containing Ets transcription factor (spdef) (P < 0.05). In conclusion, the defatted black soldier fly meal improves gut health and enhances pathogen resistance, ultimately leading to the increased survival rates of Nile tilapia when exposed to A. veronii.

Black Soldier Fly Larvae Meals With and Without Stickwater Highly Utilized in Freshwater by Atlantic salmon (Salmo salar) Parr

Black soldier fly larvae (BSFL) meal is a promising sustainable protein source for aquafeeds. Processing BSFL into meal and oil can be based on wet rendering technology where the raw material is heat treated and mechanically separated into press cake, stickwater (SW), and oil. In this study, to verify the effect of SW reincorporation into the press cake, dried BSFL cake and SW meal were included in feed mixes before extrusion. Four experimental feeds were prepared, containing 100 g kg-1 BSFL meal with a cake/SW ratio of 100/0, 90/10, 80/20 and 60/40 g kg-1, respectively and compared to a control feed in a trial with Atlantic salmon parr reared in freshwater. The feeds had similar nutritional value and all feeds were highly digestible. The highest content of manganese (Mn) was found in the BSFL cake feed (120 mgkg-1), was reduced with increased SW inclusion and lowest in the control feed. There were no dietary differences in growth or welfare with increased SW inclusion, and no negative impact of high dietary Mn levels. The high Mn content was not accumulated in the fish, and only resulted in an increased excretion of Mn. Further studies are needed to verify these results in Atlantic salmon postsmolt.

The Role of Black Soldier Fly Larvae in Optimizing Performance and Amino Acid Composition in Thai Native Chicken

The objective of this study was to investigate the effects of black soldier fly larvae (BSFL) inclusion on the performance, economic return, carcass traits, meat quality, amino acid profile, and purine content in the breast meat of Thai native chickens (TNCs) (Pradu Hang Dam Mor Kor 55: PD) from 10 to 70 days of age. A total of 216 ten-day-old PD chickens (108 males and 108 females) were randomly assigned to three dietary treatments with four replicates per treatment (18 birds per replicate, with a 1:1 male-to-female ratio). The treatments included (T1) control diet with soybean meal as the main protein source, (T2) 10% BSFL meal replacing soybean meal, and (T3) 12% BSFL meal replacing soybean meal. The results showed that BSFL inclusion had no significant effect on overall growth performance (p > 0.05), but it reduced abdominal fat and feed cost per gain while improving economic returns (p < 0.05). Additionally, BSFL increased some breast meat amino acid profiles, such as serine, glutamic acid, threonine, arginine, and lysine (p < 0.05), and increased total purine content (p < 0.05), although the values were still within the safe limit for human consumption. These results suggest that BSFL can be used as a sustainable alternative protein source in Thai native chicken diets without compromising product performance or quality.

Evaluation of nutritional and techno-functional aspects of black soldier fly high-protein extracts in different developmental stages

The global need for sustainable protein sources has contributed to the search for alternatives to conventional livestock and aquaculture feed. The black soldier fly (BSF) is a potential option for sustainable protein production due to its ability to convert organic waste into high-value biomass efficiently. To maximise its feed, food application, and resource recovery potential, the nutritional composition and techno-functional properties must be analysed in different developmental stages. This research assesses BSF as a sustainable protein source by an analysis of its growth, nutritional profile, and techno-functional characteristics. This study aims to evaluate the biomass conversion efficiency, analyse the nutritional composition, and examine the high-protein extract's techno-functional properties of BSF at various life stages. BSF eliminated 49.3 ± 0.44% of the DM of the substrate throughout the 12-day development period. Notably, BSF had a 93.6 ± 11.11% survival rate and a food conversion ratio of about 1.6 ± 0.07, demonstrating its outstanding ability to transform organic materials into useful biomass. Protein content varied significantly between life stages, ranging from 31.1 ± 0.31w/w% in larvae, 39.0 ± 0.15 w/w% in pupae, and 65.5 ± 0.18 w/w% in adults. Adults had a fat level of 22.3 ± 0.45 w/w%, whereas larvae and pupae had a fat content of 32.5 ± 0.32 w/w% and 25.8 ± 0.60 w/w%, respectively. The ash content of larvae, pupae, and adults was 6.1 ± 0.03 w/w%, 9.8 ± 0.21 w/w%, and 4.5 ± 0.01 w/w%, respectively. The percentage of carbohydrates ranged from 6.2 ± 0.50 w/w% in adults to 19.3 ± 0.50 w/w% in pupae and 13.6 ± 0.12 w/w% in larvae. Notably, BSF adult protein showed improved solubility in the pH range of 9-10. The oil holding capacity of BSF larvae high-protein extracts was lower than that of pupae, which was lower than adults. Pupae of the BSF had the maximum foam volume, whereas larvae and adults had somewhat lower values. The high-protein extracts from BSF larvae had the best emulsifying ability. The gelling capabilities of BSF high-protein extracts were investigated using a heat-induced technique, which revealed the commencement of gelation at different temperature ranges for larvae, pupae, and adults. This study highlights the diverse potential of BSF as a sustainable protein source, providing solutions for organic by-product management, resource recovery, and food sector innovation. Moreover, the different techno-functional properties of the BSF proteins in different life stages could indicate diverse applicability in various food products and the creation of novel products based on BSF-derived proteins.

Transformations of Head Structures During the Larval Development of the Black Soldier Fly Hermetia illucens (Stratiomyidae, Diptera)

Larvae of the black soldier fly, Hermetia illucens, are currently intensively studied, owing to their potential importance in various fields such as waste bioconversion, forensic entomology, and food supply for humans and life stock. Despite the increased attention, a detailed anatomical documentation of the larvae using modern methods is lacking, and even statements on the number of larval stages are contradictory. Misinterpretations of the ontogeny of this species have led to frequent erroneous identifications of the last larval instar as pupa. Consequently, many studies with a focus on larval morphology have neglected the last larval stage. In this contribution, we describe and document morphological changes of the larval head throughout the postembryonic development, with emphasis on the transition between the last two instars. This is characterized by a crucial behavioral shift from a feeding stage to a stage of increased vagility. We show that different cephalic structures undergo major changes, especially the mandibulo-maxillary complex and the digestive tract, and associated muscles. Our measurements of the body length and the length of the head capsule tentatively confirm that the larval development of H. illucens passes through seven instars.

Hermetia illucens-derived chitosan as a promising sustainable biomaterial for wound healing applications: development of sponge-like scaffolds

Chitosan (CS), a biopolymer known for its wound-healing properties, has garnered significant interest in biomedical research. This study explores the potential of two Hermetia illucens-derived CS types-unbleached CS and bleached CS-as novel biomaterials for wound-healing applications, in comparison with commercial CS derived from the shells of Pandalus borealis (cold-water shrimp). CS was extracted from pupal exuviae, a byproduct of insect farming, which supports a circular economy by converting waste into valuable molecules for biomedical applications. Unbleached CS exhibited viscosity and viscoelastic properties comparable to those of commercial CS. The critical entanglement concentration (CEC) of unbleached CS (1.15 ± 0.05 % w/v) was similar to that of commercial CS (1.18 ± 0.09 % w/v). Moreover, both Hermetia illucens-derived CS types (unbleached and bleached) demonstrated a greater capability to enhance fibroblast viability (135 ± 7 % and 123 ± 6 %, respectively) compared to commercial CS (115 ± 7 %). Further investigation revealed that unbleached CS exhibited increased antioxidant activity, reversing >30 % of the loss of viability caused by H2O2 treatment, and demonstrated anti-inflammatory properties, decreasing IL-6 levels by 66 ± 2 %. Sponge-like scaffolds based on unbleached CS and commercial CS were prepared via freeze-drying. When comparing structural and functional properties of commercial and unbleached CS scaffolds, the unbleached CS scaffolds exhibited higher porosity (67.9 ± 2.7 %), smaller pore size (216 ± 35 nm), higher swelling ratio (25.4 ± 1.9), greater resistance to degradation, and enhanced fibroblast proliferation. These findings underscore the potential of insect-derived CS as a sustainable and bioactive material for wound healing. However, further research is required to fully understand its interactions and mechanisms in tissue repair.

Mismatched menu: the incompatibility of adult black soldier flies as praying mantis feed

Praying mantises are known for their striking predatory behavior and are becoming increasingly popular with hobbyists and for scientific research. As generalist predators with a wide range of insect-based diets, it is crucial to identify suitable prey options, especially for restricted environments such as terrariums, which are limited compared to the wild. This study investigates the use of adult black soldier flies (BSF; Hermetia illucens; Linnaeus, 1758) as a sole food source for two mantis species, Chlidonoptera lestoni (Roy & Leston, 1975) and Hierodula patellifera (Serville, 1839), while assessing their suitability and potential challenges associated with their digestion. The BSF is widely recognized for its high nutritional value and ease of rearing, making it an attractive prey candidate for mantises. Although natural capture behavior and high feed acceptance have been observed, adult BSF seem not to be suitable as sole feed for both mantises. Our results suggest that imbalances in macronutrients, particularly the protein/fat ratio, may contribute to high mortality. The use of BSF as a mono-diet could also limit access to a variety of beneficial microorganisms that are essential for maintaining a healthy gut microbiota in mantises, thereby affecting their immunity and well-being in captivity. In addition, the possible presence of pathogenic microorganisms in the BSF could also have affected the mantises' survival. Future studies should focus on the nutritional adjustment of BSF, as their chemical composition is strongly dependent on the feed they are reared on.

Prediction of total lipids and fatty acids in black soldier fly (Hermetia illucens L.) dried larvae by NIR-hyperspectral imaging and chemometrics

The unique fatty acid composition of BSF larvae oil makes it suitable for various applications, including use in animal feed, aquaculture, biodiesel production, biomaterials, and the food industry. Determination of BSF larvae composition usually requires analytical methods with chemicals, thus needing emerging techniques for fast characterization of its composition. In this study, Near Infrared Hyperspectral Imaging (NIR-HSI) (928 - 2524 nm) coupled with chemometrics was applied to predict the lipid content and fatty acid composition in intact black soldier fly (BSF) larvae. Partial Least Squares Regression (PLSR) and Support Vectors Machine Regression (SVMR) models, combined with two variable selection methods, Interval Partial Least Squares (iPLS) and Bootstrapping Soft Shrinkage (BOSS), were compared. PLSR reached a good performance to predict myristic acid with Root Mean Square Error in prediction (RMSEP) = 0.45 %, while SVMR reached values of Ratio to Prediction Deviation (RPD) > 3 to predict total lipid content, lauric acid, myristic acid, palmitic acid and oleic acid. In addition, selecting wavelength by BOSS improved PLSR models (6 - 15 % increases in RPD), while iPLS improved SVMR model to predict palmitic acid (16 % increases in RPD). The study emphasizes the advantages of NIR-HSI as a non-invasive, rapid method for lipid and fatty acid quantification, which can be highly valuable for industrial applications such as monitoring BSF larvae feeding systems to ensure high-quality oil production.

Gut microbial communities and transcriptional profiles of black soldier fly (Hermitia illucens) larvae fed on fermented sericulture waste

Sericulture waste poses significant challenges to industrial and environmental safety. Black soldier fly larvae (BSFL) offer a promising solution for organic waste management by converting it into insect protein. This study aimed to develop a microbial fermented method for utilizing sericulture waste to feed BSFL and explore the underlying mechanisms. Our results showed that all fermented sericulture waste groups had positive effects on body weight, survival rate, substrate consumption rate, and substrate conversion rate. Metagenomic analysis revealed a notable increase in the abundances of commensal genera, including Sedimentibacter, Clostridium, Enterococcus, Bacteroides, and Bacillus, in the gut of BSFL fed on sericulture waste fermented with the most effective combination of microbial strains (B. subtilis, B. licheniformis, and E. faecalis). In contrast, BSFL reared on unfermented sericulture waste exhibited higher abundances of potentially pathogenic and harmful genera, including Providencia, Klebsiella, Escherichia, Brucella, and Enterobacter. Clusters of orthologous genes (COG) analysis indicated that altered microbial communities in the fermented group mainly participated in metabolic pathways, defense mechanism, and signal transduction mechanism. Transcriptome analysis further revealed that the upregulated genes were functionally associated with key metabolic pathways and immune mechanisms in the fermented group. These findings underscore the pivotal role of selected microbial fermentation in utilizing sericulture waste as BSFL feed, providing a sustainable solution for organic waste management.

Microbial profiling of black soldier fly larvae reared on substrates supplemented with different mineral sources originating from phosphorus recycling technologies

BACKGROUND

Innovations to establish agricultural value chains utilising side streams and their reintegration into the feed and food supply are of great importance. Recyclates derived from biomass and waste are therefore becoming increasingly important as sources of nutrients. The larvae of the black soldier fly (BSF; Hermetia illucens) demonstrate considerable potential as livestock feed due to their ability to utilise a wide range of organic substrates. In this study, BSF larvae (BSFL) were reared on four different substrates: chicken feed diet (CD), high-fibre Gainesville fly diet (FD), or FD supplemented either with biochar (FD + BCH) or single superphosphate (FD + SSP) recyclates from sewage sludge processing. To validate the hypothesis that endogenous and substrate-associated microbiota significantly contribute to substrate conversion, the microbiota profiles of BSFL gut and frass were analysed by 16S rRNA gene amplicon sequencing. Results were associated to the different substrates as well as body composition, growth performance data, and mineral concentration of the larvae.

RESULTS

The CD substrate was superior in terms of larval growth, although it caused a lower microbial alpha diversity in the larval intestine and frass compared to FD, with a dominance of Morganellaceae and families of Lactobacillales. The addition of the two sewage sludge derived products to the FD substrate significantly increased the calcium content of BSFL, while the phosphorus content was only increased by the addition of SSP. The shifts in the microbiota profiles of BSFL gut and frass indicated that BCH contributed to the regulation of the microbial milieu with suppressing the growth of potentially pathogenic microbes. The addition of SSP resulted in an enrichment of microorganisms with attributed phosphate-solubilising properties such as Pseudomonas and fungal species, likely being responsible for improving the bioavailability of phosphorus from the substrate.

CONCLUSIONS

The results demonstrate the high adaptability of the BSFL and its ability to change the substrate through specific microbiota in such a way that conditions are created for an optimal nutrient supply and thus growth of the larvae.

AWGE-ESPCA: An edge sparse PCA model based on adaptive noise elimination regularization and weighted gene network for Hermetia illucens genomic data analysis

Hermetia illucens is an important insect resource. Studies have shown that exploring the effects of Cu2+-stressed on the growth and development of the Hermetia illucens genome holds significant scientific importance. There are three major challenges in the current studies of Hermetia illucens genomic data analysis: firstly, the lack of available genomic data which limits researchers in Hermetia illucens genomic data analysis. Secondly, to the best of our knowledge, there are no Artificial Intelligence (AI) feature selection models designed specifically for Hermetia illucens genome. Unlike human genomic data, noise in Hermetia illucens data is a more serious problem. Third, how to choose those genes located in the pathway enrichment region. Existing models assume that each gene probe has the same priori weight. However, researchers usually pay more attention to gene probes which are in the pathway enrichment region. Based on the above challenges, we initially construct experiments and establish a new Cu2+-stressed Hermetia illucens growth genome dataset. Subsequently, we propose AWGE-ESPCA: an edge Sparse PCA model based on adaptive noise elimination regularization and weighted gene network. The AWGE-ESPCA model innovatively proposes an adaptive noise elimination regularization method, effectively addressing the noise challenge in Hermetia illucens genomic data. We also integrate the known gene-pathway quantitative information into the Sparse PCA(SPCA) framework as a priori knowledge, which allows the model to filter out the gene probes in pathway-rich regions as much as possible. Ultimately, this study conducts five independent experiments and compared four latest Sparse PCA models as well as representative supervised and unsupervised baseline models to validate the model performance. The experimental results demonstrate the superior pathway and gene selection capabilities of the AWGE-ESPCA model. Ablation experiments validate the role of the adaptive regularizer and network weighting module. To summarize, this paper presents an innovative unsupervised model for Hermetia illucens genome analysis, which can effectively help researchers identify potential biomarkers. In addition, we also provide a working AWGE - ESPCA model code in the address: https://github.com/yhyresearcher/AWGE_ESPCA.

Black Soldier Fly (Hermetia illucens) Larvae as a Protein Substitute in Adverse Food Reactions for Canine Dermatitis: Preliminary Results Among Patients

Can black soldier fly (BSF) larvae be a protein substitute for managing adverse food reactions (AFRs) in dogs, specifically those with dermatitis? We evaluated BSF larvae's safety, tolerance, and effectiveness as a novel protein source in dogs with AFRs. Sixteen dogs, including eight healthy controls and eight diagnosed with AFRs, were fed a diet containing BSF larvae for four weeks. Skin conditions, including dermatological lesions and Pruritus Visual Analog Scale (PVAS) scores, and gastrointestinal signs, including relevant clinical signs, stool consistency, and hematological and biochemical parameters, were monitored. No significant gastrointestinal side effects were observed. The control and AFRs groups maintained stable body weights, while stool consistency scores did not change significantly. Moreover, skin reaction data obtained before the study were collected through interviews with the owners. The mean PVAS scores in the AFRs group were significantly higher (p < 0.05) during the self-control period (6.0 ± 1.6) when compared with other periods. However, no significant differences (p > 0.05) were observed between the pre-study baseline (2.0 ± 1.1) and scores at 2 weeks (2.3 ± 1.5) and 4 weeks (2.4 ± 1.2) of feeding with BSF-based food, which indicated that BSF larvae did not exacerbate pruritic symptoms. Hematology and blood chemistry remained within normal ranges in all dogs, indicating no adverse effects on overall health. BSF larvae were well tolerated by AFR-affected and control dogs, with no adverse clinical outcomes. The findings suggest that BSF larvae may offer a better, sustainable alternative protein source for managing AFRs in dogs, particularly in those on hypoallergenic diets. Further long-term studies are needed to confirm these results and assess the broader implications of BSF larvae diets on canine health.

Insect chitosan derived from Hermetia illucens larvae suppresses adipogenic signaling and promotes the restoration of gut microbiome balance

Chitosan, the deacetylated form of chitin, is considered a valuable source of compounds in the feed and food industries. However, the impact of Hermetia illucens larvae chitosan (HCS) with specific physicochemical characteristics on obesity mediated by lipid accumulation and microbiome dysbiosis has not been fully elucidated. We purified HCS with a low molecular weight (84 kDa), low crystallinity, and a high deacetylation rate, characterizing it through several analytical techniques, including gel permeation chromatography, FT-IR, 1H NMR, FE-SEM, and XRD analysis. HCS effectively inhibited the differentiation of 3T3-L1 preadipocytes by suppressing the production of reactive oxygen species. The adipogenic signaling of preadipocytes, mediated by the phosphorylation of mTOR and PPARγ, which are essential for the expression of fatty acid synthase, was attenuated by HCS. In mouse models fed high-fat diets, the oral administration of HCS prevented changes in white adipose tissue and liver weight and reduced plasma levels of total cholesterol. Additionally, the analysis of the microbiota using 16S rRNA revealed that HCS improved dysbiosis by modulating the composition and abundance of specific bacterial genera, including F. rodentium, L. gasseri, L. reuteri, and L. murinus. These findings highlight the potential of HCS as a candidate for the treatment of obesity-related metabolic diseases.

Enhanced waste-to-biomass conversion and reduced nitrogen emissions for black soldier fly larvae (Hermetia illucens) through modifying protein to energy ratio

The appropriate protein to energy ratio (P/E ratio) has played a crucial role in maximizing waste-to-biomass conversion and minimizing nitrogen emissions. Black soldier fly larvae (Hermetia illucens, BSFL), capable of converting organic wastes into nutrient-rich biomass, it has the potential to become an innovative solution to reduce environmental impacts and optimize waste resource utilization. However, the appropriate P/E ratio for BSFL in the waste treatment process has remained unknown so far. This study utilized several common production chain residues to prepare diets with varying P/E ratios, to observe growth performance, nutritional components, fatty acid composition, fatty acid conversion, amino acid composition, waste-to-biomass conversion, and nitrogen emission levels of the BSFL. The results indicated that by adjusting the P/E ratio within the range of 9.79-17.8 mg/kJ, biomass conversion increased from 8.79% to 11.60% (an increase of 31.97%), nitrogen conversion enhanced from 27.31% to 40.99% (an increase of 50.10%), while nitrogen emissions reduced from 2.69 g to 0.48 g (a reduction of 82.16%). Compared to other reported methods, adjusting the P/E ratio proved more effective and cost-efficient. The P/E ratio 11.67 mg/kJ is relatively more suitable for using BSFL in organic waste treatment. Due to the significant variation in nitrogen levels within typical organic waste, our research findings advocate for the mixed treatment of multiple waste types to ensure the P/E ratio close to 11.67 mg/kJ. The findings will provide new insights into the application of BSFL biotransformation technology in organic waste management.

Bioconversion of Poultry Litter into Insect Meal and Organic Frasstilizer Using Black Soldier Fly Larvae as a Circular Economy Model for the Poultry Industry: A Review

Poultry litter waste management poses a significant global challenge, attributed to its characteristics (odorous, organic, pathogenic, attracting flies). Conventional approaches to managing poultry litter involve composting, biogas generation, or direct field application. Recently, there has been a surge of interest in a novel technology that involves the bioconversion of organic waste utilizing insects (known as entomoremediation), particularly focusing on black soldier fly larvae (BSFL), and has demonstrated successful transformation of various organic waste materials into insect meal and frass (referred to as organic frasstilizer). Black soldier flies have the capacity to consume any organic waste material (ranging from livestock litter, food scraps, fruit and vegetable residues, sewage, sludge, municipal solid waste, carcasses, and defatted seed meal) and convert it into valuable BSFL insect meal (suitable for animal feed) and frass (serving as an organic fertilizer). The bioconversion of poultry litter by black soldier flies offers numerous advantages over traditional methods, notably in terms of reduced land and water requirements, lower emissions, cost-effectiveness, swift processing, and the production of both animal feeds and organic fertilizers. This review focuses on the existing knowledge of BSFL, their potential in bioconverting poultry litter into BSFL meal and frass, and the utilization of BSFL in poultry nutrition, emphasizing the necessity for further innovation to enhance this sustainable circular economy approach.

Black Soldier Fly Larvae's Optimal Feed Intake and Rearing Density: A Welfare Perspective (Part II)

The large-scale insect rearing sector is expected to grow significantly in the next few years, with Hermetia illucens L. (black soldier fly, BSF) playing a pivotal role. As with traditional livestock, it is essential to improve and ensure BSF welfare. A starting point can be an adaptation of the Five Freedoms framework. Feed availability must be optimized to meet larvae nutritional needs (freedom from hunger) while maximizing substrate conversion efficiency. Similarly, rearing density needs to be optimized to ensure well-being, particularly in large-scale operations. In this study, Control (commercial laying hen feed) and Omnivorous substrates (vegetable and meat) were used as dietary regimes. In the first trial, three feeding rates were tested: 50, 100, and 200 mg feed/larva/day; in the second trial, three rearing densities were evaluated: 5, 10, and 15 larvae/cm2. Performance parameters, including final larval weight, final frass biomass, growth rate, substrate reduction, feed conversion ratio, larval length, survival rate, larvae chemical composition, and process optimization, were studied. Our results show that a feeding rate of approximately 90 mg feed/larva/day in the Omnivorous diet and 175 mg feed/larva/day in the Control diet, along with a rearing density of 5 and 7.57 larvae/cm2, respectively, in the Omnivorous and Control diets, produced optimal growth performances ensuring larval well-being. This outcome offers valuable insights for implementing good welfare practices in the insect farming sector and optimizing rearing management and efficiency.

Dietary inclusion of black soldier fly (Hermetia illucens) larvae meal, with exogenous protease supplementation, in practical diets for striped catfish (Pangasius hypophthalmus, Sauvage 1878)

Fishmeal (FM) is a key component of commercial fish feeds, but due its unsustainable supply, the search for quality alternatives of FM has become a significant area of investigation worldwide. The insect-based proteins such as black soldier fly larvae (BSFL) are being recognized as an alternative ingredient. However, anti-nutritional factors in these alternatives may negatively affect nutrient utilization in fish. Incorporating exogenous protease enzymes as feed additives could be a promising way to improve the digestibility of these alternative ingredients. Therefore, this study aimed to evaluate the impact of dietary inclusion of BSFL meal, combined with protease supplementation, on various parameters of striped catfish (Pangasius hypophthalmus). Five diets were formulated: a control diet (FM-based), two diets with 30% and 60% BSFL inclusion (BSF30 and BSF60), and two diets with the same inclusion levels plus the incorporation of exogenous protease (BSF30P and BSF60P). One hundred fifty fish (8.26±0.02 g) were arbitrarily allocated to five groups, each with three replicates. The fish were provided with their respective diets twice per day for 60 days. In comparison to the control, fish-fed diets supplemented with protease demonstrated statistically significant lower levels of feed conversion ratio and higher growth performance regarding the final body weight and weight gain. Lipase activity in the BSF60P group was notably greater than in the control group. Protease supplementation significantly enhanced the apparent digestibility coefficient of protein, intestinal protease activity, and crude protein content in the whole body. Most hematological and biochemical parameters remained unaffected except for substantially lower triglyceride and cholesterol levels in the highest BSFL inclusion groups. These groups also showed a reduction in crude fat contents. While glutathione peroxidase and malondialdehyde levels did not change significantly from the control, the liver tissues of fish fed BSF60P diets showed considerably higher levels of antioxidant enzymes such as catalase and superoxide dismutase. The findings suggest that including 60% of a BSFL based diet, along with exogenous protease supplementation, is feasible without compromising the growth performance and health of striped catfish.

Exploring the role of the microbiome of the H. illucens (black soldier fly) for microbial synergy in optimizing black soldier fly rearing and subsequent applications

The symbiotic microbiome in the insect's gut is vital to the host insect's development, improvement of health, resistance to disease, and adaptability to the environment. The black soldier fly (BSF) can convert organic substrates into a protein- and fat-rich biomass that is viable for various applications. With the support of a selective microbiome, BSF can digest and recycle different organic waste, reduce the harmful effects of improper disposal, and transform low-value side streams into valuable resources. Molecular and systems-level investigations on the harbored microbial populations may uncover new biocatalysts for organic waste degradation. This article discusses and summarizes the efforts taken toward characterizing the BSF microbiota and analyzing its substrate-dependent shifts. In addition, the review discusses the dynamic insect-microbe relationship from the functional point of view and focuses on how understanding this symbiosis can lead to alternative applications for BSF. Valorization strategies can include manipulating the microbiota to optimize insect growth and biomass production, as well as exploiting the role of BSF microbiota to discover new bioactive compounds based on BSF immunity. Optimizing the BSF application in industrial setup and exploiting its gut microbiota for innovative biotechnological applications are potential developments that could emerge in the coming decade.

Increasing levels of fishmeal replacement by defatted black soldier fly larvae meal reduced growth performance without affecting fillet quality in largemouth bass (Micropterus salmoides)

A 90-day feeding trial was conducted to evaluate the effects of replacing dietary fishmeal (FM) with defatted black soldier fly larvae meal (BSFL) on the growth performance and fillet quality of largemouth bass (Micropterus salmoides). The largemouth bass was divided into six groups (BSFL0, BSFL15, BSFL30, BSFL45, BSFL75, and BSFL100) and fed six isonitrogenous(CP 50%, 508 g/kg) and isolipid (CL 9%, 124 g/kg) diets, in which 0, 15%, 30%, 45%, 75%, and 100% of the fishmeal was replaced with BSFL, respectively. The results showed that the final body weight (FBW) and specific growth rate (SGR) of the largemouth bass decreased with increasing BSFL content, and they were significantly lower in BSFL75 than in BSFL0. The weight gain rate (WGR) decreased with increasing BSFL content and the feed conversion ratio (FCR) of largemouth bass increased with increasing BSFL content. The saturated fatty acids (SFAs) and n-3 polyunsaturated fatty acids (PUFA) contents of the largemouth bass fillet significantly decreased, and the n-6 PUFA content of the largemouth bass fillets significantly increased with increasing dietary BSFL. The fillet b* significantly decreased with increasing BSFL content. The biological parameters, fillet proximate nutrient composition, fillet amino acid composition, skin color, and fillet texture of the largemouth bass were not affected by the replacement of BSFL. Transcriptomic analysis revealed that BSFL replacement of FM affects the immune system and metabolic processes of largemouth bass through signaling pathways such as complement and coagulation cascades, the PPAR signaling pathway, cholesterol metabolism, and fat digestion and absorption. In conclusion, a replacement level lower than 45% BSFL was suggested for the overall growth and fillet quality of largemouth bass.

Effects of black soldier fly larvae (Hermetia illucens L.) as feed supplements on muscle nutrient composition, meat quality, and antioxidant capacity in Qianbei goat

OBJECTIVE

Black soldier fly (BSF) as an animal protein feed source is currently becoming a hot research topic. This study investigated the effects of the BSF as a protein feed source for goats on slaughter performance, muscle nutrient composition, amino acids, fatty acids, minerals, and antioxidant levels.

METHODS

Thirty Qianbei Ma goats (20.30±1.09 kg) were randomly divided into three groups: the control group (GRPC) supplemented with 10% full-fat soybean, treatment 1 (GRPU) supplemented with 10% untreated BSF, and treatment 2 (GRPT) supplemented with 10% heat-treated BSF. One-way analysis of variance among groups (with Fisher's least significant difference post hoc comparison) was used in this study.

RESULTS

The nutrients, amino acids, fatty acids, minerals, and antioxidants in muscle were analyzed. The results showed that there were no significant differences in the moisture, dry matter, crude protein, ash, amino acids, and mineral content of the muscles among the three feeding groups. The slaughter rate and carcass weight of the GRPU and GRPT groups were significantly lower (p<0.05). The overall meat quality of the GRPU and GRPT groups decreased (p<0.05). The individual unsaturated fatty acids and total unsaturated fatty acids in the GRPU group were higher (p<0.05) than those in the GRPC and GRPT groups. Both GRPU and GRPT decreased (p<0.05) the antioxidant capacity of the meat.

CONCLUSION

Therefore, the heat-treated BSF had a better effect on meat quality compared to untreated BSF, but there were greater negative effects on the meat quality of GRPU and GRPT than GRPC.

New findings of terrestrial arthropods from the Azorean Islands

The knowledge on taxonomic diversity of arthropods is key to better understanding the biodiversity patterns and processes and guiding sustainable conservation strategies and practices. In the Azores, terrestrial arthropods are relatively well-inventoried following the publication of comprehensive checklists that have been regularly updated. Nevertheless, every year, new species are found as a result of new arrivals to the Archipelago and from addressing specific taxonomic lacunae. Here, we update the taxonomic terrestrial arthropod biodiversity of the Azores by reporting for the first time 13 species for the Archipelago, namely Oligonychusperseae Tuttle, Baker & Abbatiello, 1976, Textrixpinicola Simon, 1875, Pholcommagibbum (Westring, 1851), Schistocercagregaria (Forsskål, 1775), Phoracantharecurva Newman, 1840, Diachusauratus Fabricius, 1801 Phyllotretaprocera (Redtenbacher, 1849), Phyllotretastriolata (Fabricius, 1803), Diboliaoccultans (Koch, 1803), Pseudolynchiacanariensis (Macquart, 1839), Hermetiaillucens (Linnaeus, 1758), Dryocosmuskuriphilus Yasumatsu, 1951 and Ectemniuscephalotes (Olivier, 1792), and several new species records for specific islands. These species benefitted from the increase in transportation of goods and commodities, both from outside the Archipelago and between islands, to arrive and spread across the Archipelago with some of them posing new challenges to local agriculture, forestry and biodiversity conservation management.

Effects of Hermetia illucens larvae meal and astaxanthin on intestinal histology and expression of tight junction proteins in weaned piglets

The weaning phase in piglets causes significant physiological stress, disrupts intestinal integrity and reduces productivity, necessitating strategies to improve intestinal health and nutrient absorption. While current research highlights the role of diet in mitigating these adverse effects, identifying effective dietary supplements remains a challenge. This study evaluated the effects of Hermetia illucens (HI) larvae meal and astaxanthin (AST) on the intestinal histology of weaned piglets. In a controlled experiment, 48 weaned piglets were divided into six groups and received varying levels of HI larval meal (2.5% and 5%) and AST in their diets. The methodology involved comprehensive histological examinations of the small intestine, assessing absorption area, villi elongation, crypt depth, goblet cells, enterocytes and expression of ileal tight junction (TJ) proteins. The study found that HI larval meal significantly improved nutrient absorption in the jejunum and ileum (p < 0.001), thereby enhancing feed conversion. AST supplementation increased the number of enterocytes (p < 0.001). Both HI larval meal and AST positively affected intestinal morphology and function, increasing muscularis muscle mass and villi elongation (p < 0.001 and p < 0.05, respectively). The 2.5% HI meal improved the villi length to crypt depth ratio and slightly increased the goblet cell count (both p < 0.05). Ki-67 antibody analysis showed increased cell proliferation in the duodenal and jejunal crypts, particularly with the 2.5% HI meal (p < 0.001). Insect meal did not affect TJ protein expression, indicating that it had no effect on intestinal permeability. These findings suggest that HI larval meal and AST can enhance the intestinal wellness and productivity of weaned piglets.

Green chitosan extraction from Hermetia illucens breeding waste (prepupal cases): Characterization and bioadsorption activity

Heavy metal contamination has harmful consequences for the ecosystem. They are naturally non-biodegradable, and can cause severe ecotoxicity and numerous pathologies. Several bioadsorbents have been used for metal pollution control, and chitosan is one of the biomaterials that has proven to be an efficient adsorbent. The aim of the present work is to exploit the rearing waste of Hermetia illucens (prepupal cases), commonly known as the Black Soldier Fly (BSF), to produce chitin and its derivative chitosan by microwave-assisted process, and to study the interaction of this biopolymer with zinc and cadmium. All the samples obtained were characterized by several methods, including FTIR, XRD, TGA/DSC, 1H NMR, SEM, and viscosimetric studies. The chitosan obtained has interesting physicochemical properties with an acetylation degree (DA) equal to 2.3 %, Molecular weight (Mv) equal to 155 kDa, and a crystallinity index (ICr) around 51.26 %. Chitosan was also found to have an adsorption capacity of Cd and Zn around 141.05 mg·g-1 and 45 mg·g-1 respectively by absorption atomic spectroscopy (AAS). Results confirm the effectiveness of chitosan derived from BSF, obtained through an eco-friendly method, as a sustainable and efficient bioadsorbent for addressing heavy metal contamination.

Black soldier fly (Diptera: Stratiomyidae) larvae reduce cyathostomin (Nematoda: Strongylidae) eggs but develop poorly on horse manure

Cyathostomins are common digestive tract parasites of grazing horses that spread through contact with horse feces. Horse feces are colonized by a variety of organisms, some of which could serve to reduce parasite loads in horse pastures. Black soldier fly (Hermetia illucens L.; Diptera: Stratiomyidae) larvae (BSFL) could be an ideal candidate for biological control of cyathostomins, due to their near-global distribution, low risk of pathogen transmission, ability to develop on a variety of nutrient-poor substrates (including horse manure), and dramatic effect on microbial communities that cyathostomins depend on. Here, using controlled feeding bioassays, we evaluated the effect of BSFL on cyathostomin egg densities in horse manure while also tracking BSFL performance on manure relative to standard grain-based diets. We found that BSFL consumed less substrate, were slower to reach the prepupal stage, and ultimately yielded less biomass when reared on horse manure compared to grain-based diets. However, BSFL reduced average cyathostomin egg densities in horse manure by over 3-fold. Overall, our results suggest that despite horse manure being a poor substrate for BSFL growth, BSFL effectively reduce cyathostomin egg loads in infected horse manure, though the mechanisms by which they do this are uncertain. While BSFL are known to transform the microbial communities within a diversity of rearing substrates, their effect on larger, parasitic organisms in animal manures may be underappreciated. Promoting the decomposition of infected horse manure with BSFL might be a promising approach to managing parasite populations among grazing horses.

Chitin Extracted from Black Soldier Fly Larvae at Different Growth Stages

The black soldier fly (BSF) Hermetia Illucens can grow rapidly and on a wide variety of organic materials, and it is extensively used as a means of disposing of household organic waste. Different phases of the life cycle of BSF larvae (BSFL) are used in this work to extract chitin after the removal of lipids, mineral salts, and proteins. Multiple techniques, such as X-ray diffractometry, infrared spectroscopy, solid-state Nuclear Magnetic Resonance (13C ss-NMR) and thermogravimetric analysis, are used to investigate the chemical and physical characteristics of the extracted samples of chitin, which shows a high degree of acetylation (from 78% to 94%). The extracted chitin shows an increase of the thermal stability of 20 °C in the initial stage of life and 35 °C at the end of the life cycle if compared with a commercial standard. Moreover, the extracted chitin shows an increase in the crystallinity degree during the BSFL growth time (from 72% to 78%).

Hormesis of black soldier fly larva: Influence and interactions in livestock manure recycling

Black soldier fly larvae (BSFL) are considered important organisms, utilized as tools to transform waste including manure into valuable products. The growth and cultivation of BSFL are influenced by various factors, such as the presence of toxic substances in the feed and parasites. These factors play a crucial role in hormesis, and contributing to regulate these contaminants hermetic doses to get sustainable byproducts. This review aims to understand the effects on BSFL growth and activities in the presence of compounds like organic and inorganic pollutants. It also assesses the impact of microbes on BSFL growth and explores the bioaccumulation of pharmaceutical compounds, specifically focusing on heavy metals, pesticides, pharmaceuticals, indigenous bacteria, insects, and nematodes. The review concludes by addressing knowledge gaps, proposing future biorefineries, and offering recommendations for further research.

Rearing of Black Soldier Fly Larvae with Corn Straw and the Assistance of Gut Microorganisms in Digesting Corn Straw

Corn straw is considered a renewable biomass energy source, and its unreasonable disposal leads to resource waste and environmental pollution. Black soldier fly (Hermetia illucens L.) larvae (BSFL) facilitate the bioconversion of various types of organic wastes. In this study, we found that 88% of BSFL survived, and 37.4% of corn straw was digested after 14 days of feeding with corn straw. Contrary to expectations, the pretreatment of corn straw with alkaline hydrogen peroxide did not promote its digestion but rather reduced the growth and survival rates of BSFL. Acinetobacter, Dysgonomonas, and unclassified Enterobacteriaceae were the abundant genera in the BSFL gut fed with corn straw. Compared with the standard diet, the relative abundances of carbohydrate metabolism genes, such as the gene abundances of β-glucosidase and α-glucosidase, were higher with corn straw as the substrate. These results suggested that the gut microbial community could regulate suitable and functional microorganisms in response to the substrates. Furthermore, four cellulase-producing strains, namely Klebsiella pneumoniae, Proteus mirabilis, Klebsiella oxytoca, and Providencia rettgeri, were isolated from the guts of corn straw BSFL. These four strains helped increase the conversion rates of corn straw, the weights of BSFL, and survival rates. In summary, we reared BSFL with corn straw and discovered the functions of gut microorganisms in adapting to the substrates. We also isolated four cellulase-producing strains from the BSFL guts and declared the benefits of BSFL digesting corn straw.

Microplastics in the diet of Hermetia illucens: Implications for development and midgut bacterial and fungal microbiota

In a world with a population exceeding 8 billion people and continuing to grow, pollution from food and plastic waste is causing long-term issues in ecosystems. Potential solutions may be found by exploiting insect-based bioconversion. In this context, we investigated the impact of polyvinyl chloride microparticles (PVC-MPs) on the development of Hermetia illucens (black soldier fly; BSF) and its midgut bacterial and fungal microbiota. The impact of PVC-MPs was evaluated feeding BSF larvae with a PVC-MPs-supplemented diet. The larvae exposed to different PVC-MPs concentrations (2.5%, 5%, 10% and 20% w/w) developed into adults with no significant increase in pupal mortality. Faster development and smaller pupae were observed when 20% PVC-MPs was provided. The BSF larvae ingest PVC-MPs, resulting in a reduction in MPs size. Larvae exposed to PVC-MPs did not exhibit differences in gut morphology. Regarding the impact of PVC-MPs on the structure of both bacterial and fungal communities, the overall alpha- and beta-diversity did not exhibit significant changes. However, the presence of PVC-MPs significantly affected the relative abundances of Enterobacteriaceae and Paenibacillaceae among the bacteria and of Dipodascaceae and Plectospharellaceae among the fungi (including yeast and filamentous life forms), suggesting that PVC-MP contamination has a taxa-dependent impact. These results indicate that BSF larvae can tolerate PVC-MPs in their diet, supporting the potential use of these insects in organic waste management, even in the presence of high levels of PVC-MP contamination.

Dietary black soldier fly oil enhances growth performance, flesh quality, and health status of largemouth bass (Micropterus salmoides)

The study aimed to assess the effects of dietary black soldier fly oil (BSFO) on the growth performance, flesh quality, and health status of largemouth bass (Micropterus salmoides). Six iso-nitrogenous and isolipid diets were formulated by substituting fish oil and soybean oil (1/2, wt/wt) with BSFO in percentages of 0%, 20%, 40%, 60%, 80%, and 100%, respectively. The diets were fed to 960 fish (initial body weight = 16.5 g) in four replicates for 8 weeks. Indicators related to growth performance, body composition, hematology, flesh quality, expression of genes related to inflammatory cytokines and apoptosis, and the response of fish to Aeromonas veronii challenge were analyzed. The results showed that the weight gain rate was numerically improved in all BSFO substitution groups, ranging from 9.3% to 44.0% compared to the control group. The highest survival rate and the lowest hepatosomatic index and condition factor were observed in the BFSO20 group. In terms of flesh quality, the water-holding capacity of the dorsal muscle was elevated with higher levels of dietary BSFO. However, significant changes in texture properties (cohesiveness, gluing, and chewiness) were observed in the BSFO20 group (P < 0.05). Six hematological parameters related to glycolipid and liver function were optimized in most of the BFSO substitution groups. Furthermore, the expressions of six inflammation- and apoptosis-related genes (IL-1β, Bcl-xl, BAX, caspase8, TNF-α, and IL-10) were significantly affected by dietary BSFO (P < 0.05). Following bacterial challenge, the seven-day cumulative survival rates of fish were considerably increased from 10.0% in the control group to 60.0% and 66.7% in the BSFO80 and BSFO100 groups, respectively. One-variable linear regression analysis revealed that various parameters related to fish growth, flesh quality, and health status were significantly influenced by dietary BSFO substitution levels in a dose-dependent manner (P < 0.05). In conclusion, substituting around 20% of dietary fish oil and soybean oil with BSFO is promising in improving the growth performance and flesh quality of M. salmoides. However, to enhance immunity and disease resistance, it is recommended to further increase the inclusion of BSFO in the diet.

Whole-genome sequencing of two captive black soldier fly populations: Implications for commercial production

Black soldier fly (BSF; Hermetia illucens) is a promising insect species for food and feed production as its larvae can convert different organic waste to high-value protein. Selective breeding is one way to optimize production, but the potential of breeding is only starting to be explored and not yet utilized for BSF. To assist in monitoring a captive population and implementing a breeding program, genomics tools are imperative. We conducted whole genome sequencing of two captive populations separated by geographical distance - Denmark (DK) and Texas, USA (TX). Various population genetics analyses revealed a moderate genetic differentiation between two populations. Moreover, we observed higher inbreeding in the DK population, and the detection of a subpopulation within DK population aligned well with the recent foundation of the DK population from two captive populations. Additionally, we generated gene ontology annotation and variants annotation for wider potential applications. Our findings establish a robust marker set for research in population genetics, facilitating the monitoring of inbreeding and laying the groundwork for practical breeding programs for BSF.

Unlocking the potential of black soldier fly frass as a sustainable organic fertilizer: A review of recent studies

Using Hermetia illucens, or Black Soldier Fly (BSF) frass as an organic fertilizer is becoming increasingly popular in many countries. As a byproduct derived from BSF larvae that feed on organic waste, BSF frass has tremendous potential for preserving the environment and promoting the circular economy. Since it has diverse biochemical properties influenced by various production and environmental factors, further research is needed to evaluate its potential for extensive use in crop production and agriculture. Our review summarizes recent findings in BSF frass research by describing its composition and biochemical properties derived from various studies, including nutrient contents, biostimulant compounds, and microbial profiles. We also discuss BSF frass fertilizers' effectiveness on plant growth and contribution to environmental sustainability. Great compositions of BSF frass increase the quality of plants/crops by establishing healthy soil and improving the plants' immune systems. Special emphasis is given to potentially replacing conventional fertilizer to create a more sustainable cropping system via organic farming. Besides, we discuss the capability of BSF bioconversion to reduce greenhouse gas emissions and improve the socioeconomic aspect. The prospects of BSF frass in promoting a healthy environment by reducing greenhouse gas emissions and improving the socioeconomic aspects of communities have also been highlighted. Overall, BSF frass offers an alternative approach that can be integrated with conventional fertilizers to optimize the cropping system. Further studies are needed to fully explore its potential in establishing sustainable system that can enhance socioeconomic benefits in the future.

Sexual dimorphism in the structural colours of the wings of the black soldier fly (BSF) Hermetia illucens (Diptera: Stratiomyidae)

The black soldier fly (BSF) Hermetia illucens (Diptera: Stratiomyidae) plays a significant role at the larval stage in the circular economy due to its ability to convert organic waste into valuable products for energy, food, feed, and agricultural applications. Many data are available on larval development and biomass generation, but basic research on this species is lacking and little is known about adult biology, in particular about the cues involved in sexual recognition. In the present study, using various instruments (stereomicroscope, scanning and transmission electron microscope, hyperspectral camera and spectrophotometer), wing ultrastructure of both sexes was analysed, reflectance and transmission spectra of the wings were measured and behavioural bioassays were carried out to measure male response to specific visual stimuli. The collected data showed the existence of sexual dimorphism in the wings of H. illucens due to iridescent structural colouration generated by a multilayer of melanin located in the dorsal lamina of the central part of the wing. Wing sexual dimorphism is particularly evident regarding the strong emission of blue light of female wings. Blue colour induces in males a strong motivation to mate. The obtained results can help to improve and optimize the breeding techniques of BSF.

Impact of age on the reproductive output of Hermetia illucens (Diptera: Stratiomyidae)

The current study examined the impact of adult black soldier fly (Hermetia illucens (L.)), age on reproductive output. Four treatments consisting of an equal sex ratio of the following combinations were used: 2-day-old males with 2-day-old females (YMYF); 6-day-old males with 2-day-old females (OMYF); 2-day-old males with 6-day-old females (YMOF); 6-day-old males with 6-day-old females (OMOF). Adult age was a significant factor for the overall number of mating events observed, with YMYF having 2.2× more than YMOF and 2.7× more than OMOF. Time was a significant factor in the number of mating events observed, with 97.8% observed on days 2-6. Age was not a significant factor for the total number of oviposition events, but the inclusion of time as a factor was significant, with 91.5% of all events occurring on days 2-6. Treatment and trial significantly interacted with egg production. This response can be attributed to treatments containing old females, which had a 50% variation in egg output across trials. Treatments containing young females were consistent in terms of egg production. As anticipated, due to oviposition events, 94.8% of total eggs were oviposited on days 2-6. Fecundity and egg hatch were also significantly impacted by female age, with a 50% reduction in both cases across trials occurring in old females. Young females paired with old males had a 20% reduction in egg hatch, but this difference was not statistically significant.

Diverting organic waste from landfills via insect biomanufacturing using engineered black soldier flies (Hermetia illucens)

A major roadblock towards the realisation of a circular economy are the lack of high-value products that can be generated from waste. Black soldier flies (BSF; Hermetia illucens) are gaining traction for their ability to rapidly consume large quantities of organic wastes. However, these are primarily used to produce a small variety of products, such as animal feed ingredients and fertiliser. Using synthetic biology, BSF could be developed into a novel sustainable biomanufacturing platform to valorise a broader variety of organic waste feedstocks into enhanced animal feeds, a large variety of high-value biomolecules including industrial enzymes and lipids, and improved fertiliser.

Resource Utilization of Residual Organic Sludge Generated from Bioenergy Facilities Using Hermetia illucens Larvae

Residual organic sludge generated from bioenergy facilities (BF-rOS) is often disposed instead of recycled, thus contributing to further environmental pollution. This study explored the resource utilization of BF-rOS using Hermetia illucens larvae (BSFL). When BF-rOS was fed to BSFL for two weeks, the dry weight per individual BSFL was approximately 15% of that of BSFL that were fed food waste (FW). However, the dry weight increased by approximately two-fold in BSFL that were fed effective microorganism (EM)-supplemented BF-rOS containing 60% moisture. However, under both conditions, the BSFL did not mature into pupae. In contrast, the highest dry weight per BSFL was observed with the BF-rOS/FW (50%:50%) mixture, regardless of EM supplementation. Furthermore, the highest bioconversion rate was observed when the BSFL were fed the BF-rOS/FW (50%:50%) mixture, and the frass produced by the BSFL contained fertilizer-appropriate components. In addition, the nutritional components of the BSFL exhibited a nutrient profile suitable for animal feed, except for those fed BF-rOS only. In conclusion, this investigation demonstrates that BF-rOS should be recycled for fertilizer production by mixing it with FW as a BSFL feed, which generates the valuable insect biomass as potential nutrition for animal feeding.

Black soldier fly larvae oil (Hermetia illucens L.) calcium salt enhances intestinal morphology and barrier function in laying hens

This study aimed to determine the influence of black soldier fly larvae oil calcium salt (BSFLO-SCa) supplementation on performance, jejunal histomorphology and gene expression of tight junctions and inflammatory cytokines in laying hens. A total of 60 ISA Brown laying hens (40 wk of age) were divided into 3 treatment groups, including a control group fed a basal diet (T0) and basal diets supplemented with 1% (T1) and 2% (T2) of BSFLO-SCa. Each treatment group consisted of 5 replicates with 4 laying hens each. Results showed that 1% and 2% BSFLO-SCa supplementation significantly reduced (P < 0.05) feed conversion ratio (FCR), while egg weight (EW) increased (P < 0.05). The inclusion with 2% increased (P < 0.05) both egg production (HDA) and mass (EM). The addition of 1% and 2% BSFLO-SCa significantly increased (P < 0.05) villus height (VH) and villus width (VW), while crypt depth (CD) significantly increased (P < 0.05) with 2% BSFLO-SCa. The tight junction and gene expression of claudin-1 (CLDN-1), junctional adhesion molecules-2 (JAM-2), and occludin (OCLN) were significantly upregulated (P < 0.05) with 2% BSFLO-SCa. The pro-inflammatory cytokines and gene expression of interleukin-6 (IL-6) was significantly downregulated (P < 0.05) with the addition of BSFLO-SCa, while gene expression of interleukin-18 (IL-18), toll-like receptor 4 (TLR-4), and tumor necrosis factor-α (TNF-α) were downregulated with 2% BSFLO-SCa. On the other hand, the anti-inflammatory cytokines and gene expression of interleukin-13 (IL-13) and interleukin-10 (IL-10) were significantly upregulated (P < 0.05) at 2% BSFLO-SCa. In conclusion, dietary supplementation with 2% BSFLO-SCa improved productivity, intestinal morphology and integrity by upregulating tight junction-related protein of gene expression of laying hens. In addition, supplementation with BSFLO-SCa enhanced intestinal immune responses by upregulating anti-inflammatory and downregulating pro-inflammatory cytokine gene expression.

Effects of pyrethroid and organophosphate insecticides on reared black soldier fly larvae (Hermetia illucens)

Black soldier fly larvae (Hermetia illucens) receive growing interest as a potential alternative animal feed source. These insects may be exposed to insecticide residues in the rearing substrate. This study aimed to investigate the effects of six different pyrethroid and organophosphate insecticides on this insect species' performance. The toxicity of two "model" substances for each of these classes (cypermethrin; pirimiphos-methyl) was quantified, with and without the synergist piperonyl butoxide (PBO). Critical effect doses corresponding to 10% yield (CED10) for cypermethrin (0.4 mg/kg) and pirimiphos-methyl (4.8 mg/kg) were determined. The addition of PBO to cypermethrin enhanced its relative potency with a factor 2.6. These data were compared against the relative toxicity of two analogue substances in each class (permethrin, deltamethrin; chlorpyrifos-methyl, malathion). Results suggest that exposure to concentrations complying with legal limits can cause significant reductions in yield. Exposure to multiple substances at lower concentrations resulted in negative additive and synergistic effects. Of the tested substances, deltamethrin was most toxic, causing 94% yield at 0.5 mg/kg. Analytical results suggested that transfer of tested substances to the larval biomass was substance- and concentration-specific, but appeared to be correlated to reduced yields and the presence of PBO. Transfer of organophosphates was overall low (<2%), but ranged from 8% to 75% for pyrethroids. Due to very low limits in insect biomass (∼0.01 mg/kg), high transfer may result in noncompliance. It is recommended that rearing companies implement lower contractual thresholds, and that policymakers consider adjusting legally allowed maximum residue levels in insect feed.

Black soldier fly (Hermetia illucens L.): A potential small mighty giant in the field of cosmeceuticals

Background and Aims

Natural products are widely used in the pharmaceutical and cosmetics industries due to their high-value bioactive compounds, which make for "greener" and more environmentally friendly ingredients. These natural compounds are also considered a safer alternative to antibiotics, which may result in antibiotic resistance as well as unfavorable side effects. The development of cosmeceuticals, which combine the cosmetic and pharmaceutical fields to create skincare products with therapeutic value, has increased the demand for unique natural resources. The objective of this review is to discuss the biological properties of extracts derived from larvae of the black soldier fly (BSF; Hermetia illucens), the appropriate extraction methods, and the potential of this insect as a novel active ingredient in the formulation of new cosmeceutical products. This review also addresses the biological actions of compounds originating from the BSF, and the possible association between the diets of BSF larvae and their subsequent bioactive composition.

Methods

A literature search was conducted using PubMed and Google Scholar to identify and evaluate the various biological properties of the BSF.

Results

One such natural resource that may be useful in the cosmeceutical field is the BSF, a versatile insect with numerous potential applications due to its nutrient content and scavenging behavior. Previous research has also shown that the BSF has several biological properties, including antimicrobial, antioxidant, anti-inflammatory, and wound healing effects.

Conclusion

Given the range of biological activities and metabolites possessed by the BSF, this insect may have the cosmeceutical potential to treat a number of skin pathologies.

Mitigation Strategies against Food Safety Contaminant Transmission from Black Soldier Fly Larva Bioconversion

The black soldier fly larva, Hermetia illucens, can efficiently convert organic waste into biomatter for use in animal feed. This circularity comes with a risk of contaminating downstream consumers of the larval products with microbes, heavy metals, and other hazards potentially present in the initial substrate. This review examines research on mitigation techniques to manage these contaminants, from pretreatment of the substrate to post-treatment of the larvae. While much research has been done on such techniques, little of it focused on their effects on food safety contaminants. Cheap and low-technology heat treatment can reduce substrate and larval microbial load. Emptying the larval gut through starvation is understudied but promising. Black soldier fly larvae accumulate certain heavy metals like cadmium, and their ability to process certain hazards is unknown, which is why some government authorities are erring on the side of caution regarding how larval bioconversion can be used within feed production. Different substrates have different risks and some mitigation strategies may affect larval rearing performance and the final products negatively, so different producers will need to choose the right strategy for their system to balance cost-effectiveness with sustainability and safety.

Evaluation of the Microbial Quality of Hermetia illucens Larvae for Animal Feed and Human Consumption: Study of Different Type of Rearing Substrates

In the context of climate change and depletion of natural resources, meeting the growing demand for animal feed and human food through sufficient, nutritious, safe, and affordable sources of protein is becoming a priority. The use of Hermetia illucens, the black soldier fly (BSF), has emerged as a strategy to enhance the circularity of the agri-food chain, but its microbiological safety remains a concern. The aim of the present study was to systematically review available data on the microbiological quality of BSF and to investigate the impact of using four different rearing substrates including classic options allowed by the EU regulation (cereals, fruits, vegetables) and options not allowed by EU regulations regarding vegetable agri-food (co-products, food at shelf life, and meat). A total of 13 studies were collected and synthesized, including 910 sample results, while 102 new sample results were collected from the present experiments in three farms. Both datasets combined revealed a high level of contamination of larvae, potentially transmitted through the substrate. The main pathogenic bacteria identified were Bacillus cereus, Clostridium perfringens, Cronobacter spp., Escherichia coli, Salmonella spp., and Staphylococcus aureus coagulase-positive, while Campylobacter spp. and Listeria monocytogenes were not detected. Any of these four substrates were excluded for their use in insect rearing; however, safety concerns were confirmed and must be managed by the operators of the sector using microbial inactivation treatment after the harvest of the larvae in order to propose safe products for the market. The results obtained will guide the definition of the control criteria and optimize the following manufacturing steps.

The future in the litter bin - bioconversion of food waste as driver of a circular bioeconomy

Bioconversion of organic waste requires the development and application of rather simple, yet robust technologies capable of transferring biomass into energy and sustainable materials for the future. Food waste plays a significant role in this process as its valorisation reduces waste and at the same time avoids additional exploitation of primary resources. Nonetheless, to literally become "litterate". extensive research into such robust large-scale methods is required. Here, we highlight some promising avenues and materials which fulfill these "waste to value" requirements, from various types of food waste as sustainable sources for biogas, bioethanol and biodiesel to fertilizers and antioxidants from grape pomace, from old-fashioned fermentation to the magic of anaerobic digestion.

Metabolic performance and feed efficiency of black soldier fly larvae

The black soldier fly (BSF), Hermetia illucens, is used in entomoremediation processes because its larvae can use a variety of organic residues with high efficiency. However, feed efficiencies are variable and characterized by uncertainties. Recently developed growth and metabolic performance models have predicted across different studies that BSF larvae have used 53%-58% of the feed components they have assimilated, in terms of carbon equivalents, for growth throughout their lifetime when reared on chicken feed. This is termed their average net growth efficiency. The remainder of the carbon has been lost as CO2. However, mass balances made under similar conditions show that the weight gained by BSF larvae corresponds to only 14%-48% of the feed substrates removed, indicating substrate conversion efficiency. Both performance indicators show even greater variability if more feed substrates are considered. Feed assimilation and growth rates, costs of growth, maintenance, and larval lifespan have been shown to affect how efficiently BSF larvae convert feed into growth. The differences between average net growth efficiencies and substrate conversion efficiencies further indicate that feed is often not used optimally in entomoremediation processes and that the overall yield of such processes is not determined by larval performance alone but is the result of processes and interactions between larvae, substrates, microbes, and their physical environment. The purpose of this study is to illustrate how quantification of the metabolic performance of BSF larvae can help improve our understanding of the role of the larvae in entomoremediation processes.

Advancing pathogen surveillance by nanopore sequencing and genotype characterization of Acheta domesticus densovirus in mass-reared house crickets

Rapid and reliable detection of pathogens is crucial to complement the growing industry of mass-reared insects, in order to safeguard the insect colonies from outbreak of diseases, which may cause significant economic loss. Current diagnostic methods are mainly based on conventional PCR and microscopic examination, requiring prior knowledge of disease symptoms and are limited to identifying known pathogens. Here, we present a rapid nanopore-based metagenomics approach for detecting entomopathogens from the European house cricket (Acheta domesticus). In this study, the Acheta domesticus densovirus (AdDV) was detected from diseased individuals using solely Nanopore sequencing. Virus reads and genome assemblies were obtained within twenty-four hours after sequencing. Subsequently, due to the length of the Nanopore reads, it was possible to reconstruct significantly large parts or even the entire AdDV genome to conduct studies for genotype identification. Variant analysis indicated the presence of three AdDV genotypes within the same house cricket population, with association to the vital status of the diseased crickets. This contrast provided compelling evidence for the existence of non-lethal AdDV genotypes. These findings demonstrated nanopore-based metagenomics sequencing as a powerful addition to the diagnostic tool kit for routine pathogen surveillance and diagnosis in the insect rearing industry.

Black Soldier Fly Larvae Meal vs. Soy Protein Concentrate Meal: A Comparative Digestibility Study in Barramundi (Lates calcarifer)

Black soldier fly larvae meal (BSFM) from Hermetia illucens has emerged as a dependable protein source in aquaculture. This study aimed to assess BSFM's digestibility in barramundi juveniles and compare it to soy protein concentrate meal (SPCM). Four diets (control, 30% BSFM; 30% SPCM; and commercial feed control) were tested on 1,800 barramundi juveniles (weight: 71.1 g) over 51 days in a recirculating aquaculture system (RAS). The final body weight (FBW) of fish fed with BSFM reached 222.2 (± 8.7), with a thermal-unit growth coefficient (TGC) of 4.33 (± 0.15) and a feed conversion ratio (FCR) of 1.04 (± 0.01). While BSFM and SPCM inclusion did not significantly impact FBW, body weight gain (BWG), TGC, or survival rates (P  > 0.05), FCR increased. BSFM significantly raised total feed intake (P < 0.05) but did not affect daily feed intake (P  > 0.05). Importantly, BSFM and SPCM inclusion did not alter diet apparent digestibility coefficient (ADC) for any nutrient groups (P  > 0.05), with BSFM showing high ADC for dry matter (76.8%), crude protein (93.2%), and gross energy (83.9%). No significant difference (P  > 0.05) was observed in these ADCs between BSFM and SPCM. The high digestibility of BSFM in warm seawater RAS (29.4°C) under high stocking density (33.7 kg m-3) supports its efficacy in contemporary barramundi farming.

Local circular economy: BSF insect rearing in the Italian Agri-Food Industry

With a growing population, both food and waste production will increase. There is an urgent need for innovative ways of valorizing waste. The black soldier fly (Hermetia illucens L.) efficiently converts agri-food by-products (BPs) into high-quality materials; its rearing process yields larvae (BSFL) rich in fat and protein for feed purposes, with "frass" acting as organic fertilizer. While the insect rearing sector is expanding, few producers use BPs. Therefore, a case study approach was adopted to evaluate the potential for establishing an Italian BSFL production plant on BPs available on the territory. After contacting more than 115 agri-food companies (maximum 100 km from the BSFL plant), they were classified based on sector, distance, size, and BPs (quantity, seasonality, management). BPs with a low value (fruit and vegetable residues) were treated as waste, associated with costs and low valorization. By merging the available BPs on the territory and following the literature on BSFL nutritional needs' two diets (Scenario BSFL) were created, assessing their suitability comparing them to the current full-scale plant diet (Scenario 0). The exploitation of BPs for BSFL rearing reduced local waste production by 52 % compared to conventional composting (Scenario 0). In addition, integrating BPs into the larval feed formulation increased BSFL production value (+47 times). These results highlight the potential of locally-based insect rearing to valorize BPs and create a network of sustainable actors within the agri-food industry. Further investigations are needed to improve the connection between agri-food and insect industrial activities, expanding this framework to other regions.

Dynamic expression of cathepsin L in the black soldier fly (Hermetia illucens) gut during Escherichia coli challenge

The black soldier fly (BSF), Hermetia illucens, has the potential to serve as a valuable resource for waste bioconversion due to the ability of the larvae to thrive in a microbial-rich environment. Being an ecological decomposer, the survival of BSF larvae (BSFL) relies on developing an efficient defense system. Cathepsin L (CTSL) is a cysteine protease that plays roles in physiological and pathological processes. In this study, the full-length of CTSL was obtained from BSF. The 1,020-bp open reading frame encoded a preprotein of 339 amino acids with a predicted molecular weight of 32 kDa. The pro-domain contained the conserved ERFNIN, GNYD, and GCNGG motifs, which are all characteristic of CTSL. Homology revealed that the deduced amino acid sequence of BSF CTSL shared 74.22-72.99% identity with Diptera flies. Immunohistochemical (IHC) analysis showed the CTSL was predominantly localized in the gut, especially in the midgut. The mRNA expression of CTSL in different larval stages was analyzed by quantitative real-time PCR (RT-qPCR), which revealed that CTSL was expressed in the second to sixth instar, with the highest expression in the fifth instar. Following an immune challenge in vivo using Escherichia coli (E. coli), CTSL mRNA was significantly up-regulated at 6 h post-stimulation. The Z-Phe-Arg-AMC was gradually cleaved by the BSFL extract after 3 h post-stimulation. These results shed light on the potential role of CTSL in the defense mechanism that helps BSFL to survive against pathogens in a microbial-rich environment.

De Novo Genome Assembly at Chromosome-Scale of Hermetia illucens (Diptera Stratiomyidae) via PacBio and Omni-C Proximity Ligation Technology

Hermetia illucens is a species of great interest for numerous industrial applications. A high-quality reference genome is already available for H. illucens. However, the worldwide maintenance of numerous captive populations of H. illucens, each with its own genotypic and phenotypic characteristics, made it of interest to perform a de novo genome assembly on one population of H. illucens to define a chromosome-scale genome assembly. By combining the PacBio and the Omni-C proximity ligation technologies, a new H. illucens chromosome-scale genome of 888.59 Mb, with a scaffold N50 value of 162.19 Mb, was assembled. The final chromosome-scale assembly obtained a BUSCO completeness of 89.1%. By exploiting the Omni-C proximity ligation technology, topologically associated domains and other topological features that play a key role in the regulation of gene expression were identified. Further, 65.62% of genomic sequences were masked as repeated sequences, and 32,516 genes were annotated using the MAKER pipeline. The H. illucens Lsp-2 genes that were annotated were further characterized, and the three-dimensional organization of the encoded proteins was predicted. A new chromosome-scale genome assembly of good quality for H. illucens was assembled, and the genomic annotation phase was initiated. The availability of this new chromosome-scale genome assembly enables the further characterization, both genotypically and phenotypically, of a species of interest for several biotechnological applications.

Dynamic effects of black soldier fly larvae meal on the cecal bacterial microbiota and prevalence of selected antimicrobial resistant determinants in broiler chickens

BACKGROUND

We had earlier described the growth-promoting and -depressive effects of replacing soybean meal (SBM) with low (12.5% and 25%) and high (50% and 100%) inclusion levels of black soldier fly larvae meal (BSFLM), respectively, in Ross x Ross 708 broiler chicken diets. Herein, using 16S rRNA gene amplicon sequencing, we investigated the effects of replacing SBM with increasing inclusion levels (0-100%) of BSFLM in broiler diets on the cecal bacterial community composition at each growth phase compared to broilers fed a basal corn-SBM diet with or without the in-feed antibiotic, bacitracin methylene disalicylate (BMD). We also evaluated the impact of low (12.5% and 25%) inclusion levels of BSFLM (LIL-BSFLM) on the prevalence of selected antimicrobial resistance genes (ARGs) in litter and cecal samples from 35-day-old birds.

RESULTS

Compared to a conventional SBM-based broiler chicken diet, high (50 to100%) inclusion levels of BSFLM (HIL-BSFLM) significantly altered the cecal bacterial composition and structure, whereas LIL-BSFLM had a minimal effect. Differential abundance analysis further revealed that the ceca of birds fed 100% BSFLM consistently harbored a ~ 3 log-fold higher abundance of Romboutsia and a ~ 2 log-fold lower abundance of Shuttleworthia relative to those fed a BMD-supplemented control diet at all growth phases. Transient changes in the abundance of several potentially significant bacterial genera, primarily belonging to the class Clostridia, were also observed for birds fed HIL-BSFLM. At the finisher phase, Enterococci bacteria were enriched in the ceca of chickens raised without antibiotic, regardless of the level of dietary BSFLM. Additionally, bacitracin (bcrR) and macrolide (ermB) resistance genes were found to be less abundant in the ceca of chickens fed antibiotic-free diets, including either a corn-SBM or LIL-BSFLM diet.

CONCLUSIONS

Chickens fed a HIL-BSFLM presented with an imbalanced gut bacterial microbiota profile, which may be linked to the previously reported growth-depressing effects of a BSFLM diet. In contrast, LIL-BSFLM had a minimal effect on the composition of the cecal bacterial microbiota and did not enrich for selected ARGs. Thus, substitution of SBM with low levels of BSFLM in broiler diets could be a promising alternative to the antibiotic growth promoter, BMD, with the added-value of not enriching for bacitracin- and macrolide-associated ARGs.

CRISPR/Cas9-mediated efficient white genome editing in the black soldier fly Hermetia illucens

The CRISPR/Cas9 system is the most straightforward genome-editing technology to date, enabling genetic engineering in many insects, including the black soldier fly, Hermetia illucens. The white gene plays a significant role in the multifarious life activities of insects, especially the pigmentation of the eyes. In this study, the white gene of H. illucens (Hiwhite) was cloned, identified, and bioinformatically analysed for the first time. Using quantitative real-time polymerase chain reaction (qPCR), we found that the white gene was expressed in the whole body of the adult flies, particularly in Malpighian tubules and compound eyes. Furthermore, we utilised CRISPR/Cas9-mediated genome-editing technology to successfully generate heritable Hiwhite mutants using two single guide RNAs. During Hiwhite genome editing, we determined the timing, method, and needle-pulling parameters for embryo microinjection by observing early embryonic developmental features. We used the CasOT program to obtain highly specific guide RNAs (gRNAs) at the genome-wide level. According to the phenotypes of Hiwhite knockout strains, the pigmentation of larval stemmata, imaginal compound eyes, and ocelli differed from those of the wild type. These phenotypes were similar to those observed in other insects harbouring white gene mutations. In conclusion, our results described a detailed white genome editing process in black soldier flies, which lays a solid foundation for intensive research on the pigmentation pathway of the eyes and provides a methodological basis for further genome engineering applications in black soldier flies.