Hermetia illucens exhibits bioaccumulative potential for 15 different elements - Implications for feed and food production

Bioaccumulation of cadmium in common green bottle fly Lucilia sericata and its impact on insect development - prospect for use in feed and food production

This study aimed to investigate the bioaccumulation of cadmium from natural feed substrate and substrate enriched with CdCl2 and CdO by the common green bottle fly, Lucilia sericata (Diptera: Calliphoridae). Cadmium was determined in all developmental stages (larvae, adults, and puparial cases) of L. sericata, and its accumulation was positively correlated with concentrations in insect diets. Higher bioaccumulation factors of Cd were found in larvae and adults fed with naturally contaminated liver tissues (1.3-3.9) than those fed with liver enriched with cadmium in the form of inorganic compounds (0.4-0.9). The effect of cadmium dose on insect development was also studied. Cadmium exposure caused disorders in the metabolism of Zn, Cu, and Mn, and the effect depended on its form present in the diet. Insects must be tested for the presence of heavy metals to demonstrate their safety and quality as novel feed and food products.

Black soldier fly frass from seed waste of nitrogen-rich legumes - How long-term maturation affects the fertilizer properties?

Expanded insect production represents a source of post-breeding residues (frass) that can potentially be used as a soil additive. These types of biofertilizers are carriers of recirculated nutrients, as well as organic matter. In the present study, we investigated whether the bean waste (BW) and pea waste (PW) in the form of crushed seeds and post-production leftovers, naturally rich in proteins, were suitable as a substrate for rearing black soldier fly (Hermetia illucens) larvae. The main objective of this study was to characterize fertilizing properties of the resulting frasses (after 1 month of larvae breeding), as well as to investigate how aerobic maturation (lasted 10 months) would affect their properties. The experiment demonstrated that larval bioconversion increased the concentrations of ammonium and nitrate ions, as well as concentrations of macro- and micronutrients in the frass compared to the substrates. Raw PW frass can already be used as a fertilizer, as indicated by the appropriate ranges of Ntot, EC and C/N values, while raw BW frass had low C/N and high EC, which could contribute to phytotoxic effects. Maturation of frass improved the properties of BW frass, but worsened some characteristics of PW frass, such as an excessive increase in the C/N ratio, which could result in nitrogen immobilization. At the same time, maturation caused further increase in micro- and macronutrients concentration, which meant that both variants of the mature frass were rich in elements necessary for plant development.

Antioxidant response fail to rescue growth of Hermetia illucens L. larvae induced by copper accumulated during long-term exposure

Antioxidant indices and hemocytes apoptosis in the 6th instar larvae of Hermetia illucens., and their correlation with larval growth were evaluated by exposing larvae to different concentrations of Cu2+ for 1, 3 and 5 generations. Cu2+ accumulated in larval hemolymph showed significant dose-dependent relationship with Cu2+ concentrations in diets within a generation. Larval growth was only promoted after low concentrations of Cu2+ exposure for 1 generation, while seriously affected after high concentrations of Cu2+ exposure. Though total antioxidant capacity activity in larval hemolymph in treatment groups was all higher than that in control, it was increased at lower levels of Cu2+, while decreased with increasing Cu2+ concentrations at higher levels of Cu2+ exposure. The catalase (CAT) activity and metallothioneins (MTs) levels were also characterized as improved at lower levels of Cu2+, and inhibited at higher levels of Cu2+ exposure. However, CAT activity and MTs levels at higher Cu2+ treatments were significantly lower than that in control. Apoptosis rate of hemocytes was increased with increasing Cu2+ concentrations. Annexin V - fluorescein isothiocyanate (FITC)/ propidium iodide (PI) staining was in accordance with the results exhibited in flow cytometer. Results from transmission electron microscope and comet assay further confirmed that membrane blebbing, nuclear condensation, and DNA fragmentation were gradually apparent with increasing Cu2+ concentration. All parameters in different generation had similar dose-dependent trends, but the effects were strongest in the fifth generation. This study indicated that at some extent growth of H. illucens were associated with antioxidant responses and apoptosis induced by Cu2+.

Toxicokinetics and tissue dynamics approaches to evaluate the accumulation and elimination of cadmium in black soldier fly larvae

The black soldier fly larvae (BSFL) is a highly valued resource insect, renowned for its efficient and eco-friendly approach to the treatment of organic waste. A crucial matter that demands clarification is whether the heavy metals are eliminated or remain within BSFL bodies. Our research focused on the toxicokinetic and the dynamic tissue changes of cadmium (Cd) in BSFL exposed to low (50 mg/kg), moderate (300 mg/kg), and high levels (700 mg/kg) of Cd stress, with the goal of offering a novel perspective on this matter. Our results demonstrated a negative correlation with the BAFkinetic and a positive correlation with the BAF as Cd concentrations increased. BSFL exhibited significant rates of Cd uptake, with values for Cd50, Cd300, and Cd700 being K1= 1.3998, 0.9794, and 0.9023 g substrate glarvae-1 day-1, respectively. Across all treatments, BSFL were capable of excreting Cd, with a DT50 less than 2 days. The gut, particularly the midgut, was identified as the primary tissue for Cd enrichment. The anterior midgut played a pivotal role as a critical organ during high Cd exposure, while the middle midgut served as a stable storage organ. The posterior midgut was the preferred tissue for Cd accumulation. Following bioconversion by BSFL, the concentration and bioavailability of Cd in the resulting residue were altered. In conclusion, BSFL possess significant potential for swiftly mitigating high-concentration Cd pollution. Moreover, the application of a 2-day short-term elimination feeding strategy can significantly elevate the food safety and safety for animal consumption of BSFL.

Better Ce (III) Sorption Properties of Unprocessed Chitinous Waste from Hermetia illucens than Commercial Chitosans

Insect farming generates a new type of chitinous waste in the form of dead specimens that have died of natural causes and insect moults (puparia), particularly large amounts of which are generated during the rearing of holometabolous insects. Following the circular economy paradigm, we treated waste in the form of puparia and dead adults of H. illucens as a valuable material, i.e., as sources of chitin, and tested it as a sorbent for cerium, a lanthanide of great industrial importance. For comparison, non-treated, raw insect materials and commercial chitosans were also investigated. Chitin extracted from H. illucens showed an adsorption capacity at the same level as commercially available, marine-source chitin (approximately 6 mg Ce·g-1). However, more interestingly, raw materials exhibited much higher adsorption capacities-dead adults were similar to commercial chitosans (approximately 32 mg Ce·g-1), while puparia demonstrated twice the performance (approximately 60 mg Ce·g-1). This indicates that unprocessed waste can be used as environmentally friendly, cost-effective Ce biosorbents with comparable or even better sorption capacity than chitosans, whose production requires intense chemical processing.

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.

Multi-Elemental Analysis of Edible Insects, Scorpions, and Tarantulas from French (Online) Market and Human Health Risk Assessment Due to Their Consumption: A Pilot Study

Edible insects are becoming increasingly popular as protein alternatives to traditional animal-based products. As such, information on their elemental composition is important to ensure they are safe for human consumption. This article describes the development and validation of a rapid, reliable method for the simultaneous determination of 19 elements (Al, As, B, Ba, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Mo, Na, Pb, Se, Sr, and Zn) in edible insects by inductively coupled plasma mass spectrometry (ICP-MS) following closed vessel microwave digestion. The method was validated using three insect certified reference materials, namely black soldier fly larvae meal (BFLY-1), cricket flour (KRIK-1), and mealworm powder (VORM-1). The method was applied to analyze twelve different (whole) insect species. The maximum amount of each sample was calculated for As, Cd, and Pb with respect to their provisional tolerable daily intake values established by the Food and Agricultural Organization/World Health Organization. Most of the samples, except for scorpions and tarantulas, were safe to consume at large doses (1000-10,000 insects per day). Furthermore, most of the samples contained high levels of Fe, K, Na, and Zn, providing a preliminary overview of the nutritional profile of these novel protein alternatives.

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.

Performance of feeding black soldier fly (Hermetia illucens) larvae on shrimp carcasses: A green technology for aquaculture waste management and circular economy

Over 944 thousand tonnes of shrimp carcasses are produced worldwide during the shrimp production cycle, and black soldier fly larvae (BSFL) are a potential solution for this shrimp carcass accumulation. In this study, we evaluated the performance of BSFL feeding on shrimp carcasses. Six combinations of wheat bran and shrimp carcass powder (with replacement increments of 20 %) and one whole shrimp carcasses treatment were tested. The bioconversion rate (27.15 ± 3.66 %; p = 0.001), crude protein (55.34 ± 1.27 %; p < 0.001), and crude lipid (14.37 ± 1.86 %; p = 0.007) values of BSFL reared on whole shrimp carcasses were significantly higher than those of BSFL reared on wheat bran. Increasing the shrimp carcass amount in the feeding media resulted in significant increases in BSFL docosahexaenoic acid (with the highest value occurring for BSFL reared on whole shrimp carcasses; 1.46 ± 0.09 %; p < 0.001). Conversely, BSFL docosahexaenoic acid was not detected for BSFL reared on wheat bran. The detected heavy metal concentrations in BSFL were below the limits of the published international guidelines for animal feed. In the obtained BSFL, Salmonella was not detected, and the mould count was <10 CFU/g. The total bacterial count (Lg transformation) of obtained BSFL ranged from 7.88 to 8.07 CFU/g, and no significant differences among all treatments (p = 0.424). Overall, this study demonstrates that BSFL-based bioconversion presents a resource recovery technology for converting shrimp carcasses into high-value nutritional biomass.

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.

A novel family of defensin-like peptides from Hermetia illucens with antibacterial properties

BACKGROUND

The world faces a major infectious disease challenge. Interest in the discovery, design, or development of antimicrobial peptides (AMPs) as an alternative approach for the treatment of bacterial infections has increased. Insects are a good source of AMPs which are the main effector molecules of their innate immune system. Black Soldier Fly Larvae (BSFL) are being developed for large-scale rearing for food sustainability, waste reduction and as sustainable animal and fish feed. Bioinformatic studies have suggested that BSFL have the largest number of AMPs identified in insects. However, most AMPs identified in BSF have not yet undergone antimicrobial evaluation but are promising leads to treat critical infections.

RESULTS

Jg7197.t1, Jg7902.t1 and Jg7904.t1 were expressed into the haemolymph of larvae following infection with Salmonella enterica serovar Typhimurium and were predicted to be AMPs using the computational tool ampir. The genes encoding these proteins were within 2 distinct clusters in chromosome 1 of the BSF genome. Following removal of signal peptides, predicted structures of the mature proteins were superimposed, highlighting a high degree of structural conservation. The 3 AMPs share primary sequences with proteins that contain a Kunitz-binding domain; characterised for inhibitory action against proteases, and antimicrobial activities. An in vitro antimicrobial screen indicated that heterologously expressed SUMO-Jg7197.t1 and SUMO-Jg7902.t1 did not show activity against 12 bacterial strains. While recombinant SUMO-Jg7904.t1 had antimicrobial activity against a range of Gram-negative and Gram-positive bacteria, including the serious pathogen Pseudomonas aeruginosa.

CONCLUSIONS

We have cloned and purified putative AMPs from BSFL and performed initial in vitro experiments to evaluate their antimicrobial activity. In doing so, we have identified a putative novel defensin-like AMP, Jg7904.t1, encoded in a paralogous gene cluster, with antimicrobial activity against P. aeruginosa.

Response of Propsilocerus akamusi (Diptera: Chironomidae) to the leachates from AMD-contaminated sediments: Implications for metal bioremediation of AMD-polluted areas

Acid mine water (AMD) is a global environmental problem caused by coal mining with the characteristics of low pH and high concentrations of metals and sulfates. It is a pertinent topic to seek both economical and environmentally friendly approaches to minimize the harmful effects of AMD on the environment. Insect larvae are considered a promising solution for pollution treatment. Chironomidae is the most tolerant family to contaminants in pools and its larvae have a strong capacity for metal accumulation from sediment. This paper aimed to evaluate the larvae of Propsilocerus akamusi, a dominant species in the chironomid community, as a new species for entomoremediation in AMD-polluted areas. We detected the toxic effects of AMD on P. akamusi larvae based on their survival and the trace metals bioaccumulation capabilities of P. akamusi larvae. Moreover, we analyzed the expression patterns of four stress-response genes, HSP70, Eno1, HbV, and Hb VII in P. akamusi larvae. Our results revealed that AMD exposure did not significantly affect the survival of the P. akamusi larvae and individuals exposed to some AMD gradients even exhibited higher survival. We also observed the significantly accumulated concentrations of Fe, Ni, and Zn as well as higher bioaccumulation factors (BAFs) for Ni and Zn in the P. akamusi larvae exposure to AMD. Induced expression of Eno1 and Hb VII may play important roles in the AMD tolerance of P. akamusi larvae. This study indicated the potential application of P. akamusi larvae in the metal bioremediation of AMD-polluted areas. STATEMENT OF ENVIRONMENTAL IMPLICATION: Acid mine drainage (AMD) is a global environmental problem related to coal mining activities. AMD pollution has become a long-term, worldwide issue for its interactive and complex stress factors. Bioremediation is an effective method to remove the metals of AMD from wastewater to prevent downstream pollution. However, the disadvantages of the slow growth rate, susceptibility to seasonal changes, difficult post-harvest management, and small biomass of hyperaccumulating plants greatly limit the usefulness of phytoremediation. Insect larvae may be useful candidate organisms to overcome these shortcomings and have been considered a promising pollution solution. Propsilocerus akamusi is a dominant species in the chironomid community and is distributed widely in many lakes of eastern Asia. This species has extraordinary abilities to resist various stresses. This research is the first time to our knowledge to evaluate the application of P. akamusi as a new species in entomoremediation in AMD-contaminated areas.

Bioaccumulation of chemical elements at post-industrial freshwater sites varies predictably between habitats, elements and taxa: A power law approach

Elevated environmental levels of elements originating from anthropogenic activities threaten natural communities and public health, as these elements can persist and bioaccumulate in the environment. However, their environmental risks and bioaccumulation patterns are often habitat-, species- and element-specific. We studied the bioaccumulation patterns of 11 elements in seven freshwater taxa in post-mining habitats in the Czech Republic, ranging from less polluted mining ponds to highly polluted fly ash lagoons. We found nonlinear, power-law relationships between the environmental and tissue concentrations of the elements, which may explain differences in bioaccumulation factors (BAF) reported in the literature. Tissue concentrations were driven by the environmental concentrations in non-essential elements (Al, As, Co, Cr, Ni, Pb and V), but this dependence was limited in essential elements (Cu, Mn, Se and Zn). Tissue concentrations of most elements were also more closely related to substrate than to water concentrations. Bioaccumulation was habitat specific in eight elements: stronger in mining ponds for Al and Pb, and stronger in fly ash lagoons for As, Cu, Mn, Pb, Se, V and Zn, although the differences were often minor. Bioaccumulation of some elements further increased in mineral-rich localities. Proximity to substrate, rather than trophic level, drove increased bioaccumulation levels across taxa. This highlights the importance of substrate as a pollutant reservoir in standing freshwaters and suggests that benthic taxa, such as molluscs (e.g., Physella) and other macroinvertebrates (e.g., Nepa), constitute good bioindicators. Despite the higher environmental risks in fly ash lagoons than in mining ponds, the observed ability of freshwater biota to sustain pollution supports the conservation potential of post-industrial sites. The power law approach used here to quantify and disentangle the effects of various bioaccumulation drivers may be helpful in additional contexts, increasing our ability to predict the effects of other contaminants and environmental hazards on biota.

Determination of Arsenic Species in Edible Insects by LC-ICP-MS

BACKGROUND

Edible insects may contain arsenic. Analysis of arsenic species is necessary in order to accurately assess arsenic exposure.

OBJECTIVE

An analytical method was validated and used to determine and quantitate arsenic species in edible insects.

METHODS

Arsenic species were extracted from edible insects by heating at 100°C in 0.3 mol/L nitric acid. The concentration of arsenic species was then determined by LC-inductively coupled plasma-mass spectrometry (LC-ICP-MS) using an octadecylsilane (ODS) column with a mobile phase containing an ion-pair reagent.

RESULTS

The LOD (0.007-0.012 mg/kg), LOQ (0.021-0.038 mg/kg), repeatability (1.2-3.2%), intermediate precision (2.8-4.5%), and trueness (recoveries 97-102% based on spiked samples) of the proposed method were satisfactory for inorganic arsenic, dimethylarsinic acid (DMA), and arsenobetaine (AB) in edible insects. Total arsenic was detected in all samples obtained in Japan (Asian forest scorpion, diving beetles, giant water bug, grasshoppers, June beetles, mole crickets, male rhino beetle, female rhino beetle, sago worms, and silkworm pupae) and consisted of mostly inorganic arsenic. Beetles in particular showed relatively high levels.

CONCLUSION

Arsenic content varies among edible insect species. Feed control is important, as arsenic concentrations in edible insects may be feed dependent.

HIGHLIGHTS

Arsenic species in edible insects were analyzed by LC-ICP-MS using an ODS column with a mobile phase containing an ion-pair reagent. Inorganic arsenic was detected in most samples, with concentrations ranging from <0.04 to 29.3 mg/kg.

Upcycling of recycled minerals from sewage sludge through black soldier fly larvae (Hermetia illucens): Impact on growth and mineral accumulation

Phosphorous (P) resources are finite. Sewage sludge recyclates (SSR) are not only of interest as plant fertilizer but also as potential source of minerals in animal nutrition. However, besides P and calcium (Ca), SSR contain heavy metals. Under EU legislation, the use of SSR derivatives in animal feed is not permitted, but given the need to improve nutrient recycling, it could be an environmentally sound future mineral source. Black soldier fly larvae (BSFL) convert low-grade biomass into valuable proteins and lipids, and accumulate minerals in their body. It was hypothesized that BSFL modify and increase their mineral content in response to feeding on SSR containing substrates. The objective was to evaluate the upcycling of minerals from SSR into agri-food nutrient cycles through BSFL. Growth, nutrient and mineral composition were compared in BSFL reared either on a modified Gainesville fly diet (FD) or on FD supplemented with either 4% of biochar (FD + BCH) or 3.6% of single-superphosphate (FD + SSP) recyclate (n = 6 BSFL rearing units/group). Larval mass, mineral and nutrient concentrations and yields were determined, and the bioaccumulation factor (BAF) was calculated. The FD + SSP substrate decreased specific growth rate and crude fat of BSFL (P < 0.05) compared to FD. The FD + SSP larvae had higher Ca and P contents and yields but the BAF for Ca was lowest. The FD + BCH larvae increased Ca, iron, cadmium and lead contents compared to FD. Larvae produced on FD + SSP showed lower lead and higher arsenic concentration than on FD + BCH. Frass of FD + BCH had higher heavy metal concentration than FD + SSP and FD (P < 0.05). Except for cadmium and manganese, the larval heavy metal concentration was below the legally permitted upper concentrations for feed. In conclusion, the SSR used could enrich BSFL with Ca and P but at the expense of growth. Due to the accumulation of Cd and Mn, BSFL or products thereof can only be a component of farmed animal feed whereas in BSFL frass heavy metal concentrations remained below the upper limit authorized by EU.

Effects of undesired substances and their bioaccumulation on the black soldier fly larvae, Hermetia illucens (Diptera: Stratiomyidae)-a literature review

Black soldier fly (BSF), Hermetia illucens (L.) (Diptera: Stratiomyidae), is predominantly reared on organic wastes and other unused complementary substrates. However, BSF may have a buildup of undesired substances in their body. The contamination of undesired substance, e.g., heavy metals, mycotoxins, and pesticides, in BSF mainly occurred during the feeding process in the larval stage. Yet, the pattern of accumulated contaminants in the bodies of BSF larvae (BSFL) is varied distinctively depending on the diets as well as the contaminant types and concentrations. Heavy metals, including cadmium, copper, arsenic, and lead, were reported to have accumulated in BSFL. In most cases, the cadmium, arsenic, and lead concentration in BSFL exceeded the recommended standard for heavy metals occurring in feed and food. Following the results concerning the accumulation of the undesired substance in BSFL's body, they did not affect the biological parameters of BSFL, unless the amounts of heavy metals in their diets are highly exceeding their thresholds. Meanwhile, a study on the fate of pesticides and mycotoxins in BSFL indicates that no bioaccumulation was detected for any of the target substances. In addition, dioxins, PCBs, PAHs, and pharmaceuticals did not accumulate in BSFL in the few existing studies. However, future studies are needed to assess the long-term effects of the aforementioned undesired substances on the demographic traits of BSF and to develop appropriate waste management technology. Since the end products of BSFL that are contaminated pose a threat to both human and animal health, their nutrition and production process must be well managed to create end products with a low contamination level to achieve a closed food cycle of BSF as animal feed.

A novel type of biochar from chitinous Hermetia illucens waste with a built-in stimulating effect on plants and soil arthropods

The breeding of insects generates waste in the form of insect excrement and feed residues. In addition, a specific chitinous waste in the form of insect larvae and pupae exuvia is also left. Recent research tries to manage it, e.g., by producing chitin and chitosan, which are value-added products. The circular economy approach requires testing new, non-standard management methods that can develop products with unique properties. To date, the possibility of biochar production from chitinous waste derived from insects has not been evaluated. Here we show that the puparia of Hermetia illucens are suitable for biochar production, which in turn exhibits original characteristics. We found that the biochars have a high nitrogen level, which is rarely achievable in materials of natural origin without artificial doping. This study presents a detailed chemical and physical characterization of the biochars. Moreover, ecotoxicological analysis has revealed the biochars' stimulation effect on plant root growth and the reproduction of the soil invertebrate Folsomia candida, as well as the lack of a toxic effect on its mortality. This predisposes these novel materials with already built-in stimulating properties to be used in agronomy, for example as a carriers for fertilizers or beneficial bacteria.

Analysis of heavy metals in the conversion of lake sediment and restaurant waste by black soldier fly (Hermetia illucens)

The risk posed by heavy metals makes it difficult to dispose of sediment contaminants from dredging lakes in China. Black soldier fly (Hermetia illucens) can convert organic waste, such as restaurant waste and lake sediment, to high-value-added protein feed and fertilizer. Experimental groups were formed in this study to explore the conversion of heavy metals present in the mixture of restaurant waste and lake sediment by black soldier fly larvae (BSFL). The results demonstrated that BSFL could survive in pure sediment with an 84.76% survival rate. Relative to the substrate, BSFL could accumulate 70-90% zinc (Zn), chromium (Cr), copper (Cu), and 20-40% cadmium (Cd) and lead (Pb). The experimental group 2:3, with 40% lake sediment and 60% restaurant waste, was the best group after conversion for 15 days, which showed a 95.24% survival rate of BFSL, 82.20 mg average weight of BFSL, 8.92 mm average length of BFSL, with varying content of heavy metals such as Cu (43.22 mg/kg), Zn (193.31 mg/kg), Cd (1.58 mg/kg), Cr (25.30 mg/kg) Cr, and Pb (38.59 mg/kg) in BSFL. Furthermore, the conversion residue conforms to the relevant standards of organic fertilizer in China and can be used as organic fertilizer. Overall, the present study shows that black soldier flies can improve the resource utilization of lake sediment, especially by reducing the effect of heavy metals.

The Variety of Applications of Hermetia illucens in Industrial and Agricultural Areas-Review

Hermetia illucens (Diptera: Stratiomyidae, Linnaeus, 1978), commonly known as the black soldier fly (BSF), is a saprophytic insect, which in recent years has attracted significant attention from both the scientific community and industry. The unrestrained appetite of the larvae, the ability to forage on various organic waste, and the rapid growth and low environmental impact of its breeding has made it one of the insect species bred on an industrial scale, in the hope of producing fodder or other ingredients for various animals. The variety of research related to this insect has shown that feed production is not the only benefit of its use. H. illucens has many features and properties that could be of interest from the point of view of many other industries. Biomass utilization, chitin and chitosan source, biogas, and biodiesel production, entomoremediation, the antimicrobial properties of its peptides, and the fertilizer potential of its wastes, are just some of its potential uses. This review brings together the work of four years of study into H. illucens. It summarizes the current state of knowledge and introduces the characteristics of this insect that may be helpful in managing its breeding, as well as its use in agro-industrial fields. Knowledge gaps and under-studied areas were also highlighted, which could help identify future research directions.

Migration and Transformation of Cd in Pig Manure-Insect Frass (Hermetia illucens)-Soil-Maize System

Little is known about the fate of heavy metals in the recycling system of animal manure-black soldier fly larvae (BSFL) transformation-larval frass application. In this work, BSFL-transformed pig manure with different concentrations of exogenous cadmium (Cd) (0, 3, 15, 30 mg kg^-1), and the obtained BSFL frass fertilizer were further used in pot experiments of maize planting to explore Cd migration during the whole recycling system. Results showed that Cd addition to pig manure had no significant effects on BSFL growth or BSFL transformation performance. The Cd concentrations in BSFL frass were 10.9-19.8% lower than those in pig manure, while those in BSFL bodies were 2.3-4.0-times those of pig manure. For maize planting, only 30 mg kg^-1 of Cd treatment significantly inhibited maize growth. The BSFL frass application (under exogenous Cd treatment) enhanced Cd contents in the aboveground and underground parts of maize (3.3-57.6-times) and those in soil (0.5-1.7-times) compared with CK (no Cd addition). Additionally, 61.2-73.5% of pig manure-sourced Cd was transformed into BSFL frass and the rest entered BSFL bodies. Only a small part (0.31-1.34%) of manure-sourced Cd entered maize plants. BSFL transformation decreased the proportions of weak acid-dissolved Cd from 44.2-53.0% (manure) to 37.3-46.0% (frass). After frass application, the proportions of weak acid-dissolved Cd in soil were further decreased to 17.8-42.5%, while the residual fractions of Cd increased to 27.2-67.7%. The findings provided a theoretical basis for the rational application of BSFL frass fertilizers sourced from heavy-metal-contaminated manure.

Preliminary Data on Essential and Non-essential Element Occurrence in Processed Animal Proteins from Insects

Insects represent a valuable and environmentally friendly protein alternative in food and feed. The Farm to Fork strategy encouraged the reintroduction of animal by-products in feed production to optimise recycling and to valorise under-used resources. In order to grant safe and valuable feed products, this study investigated the black soldier fly (BSF) (Hermetia illucens) chemical risk. Samples collected in different steps of production (8 samples of substrate for culturing, 7 samples of larvae, 15 samples of protein meal, 18 samples of spent substrate) were analysed for microessential elements (chromium, copper, iron, nickel, selenium and zinc) and inorganic contaminants (aluminium, arsenic, cadmium, lead, tin and vanadium) by Inductively Coupled Plasma Mass Spectrometer (ICP-MS). Microessential elements were found in the following order: Fe > Zn > Cu > Ni > Se > Cr (mg kg^-1). Non-essential element concentrations were found lower than the set limits according to the European Union Regulations. The growing demand for alternative protein sources for feed production could be partially compensated by black soldier fly (BSF) (Hermetia illucens) meal, as it appears a good source for high-quality proteins and microessential elements which play a pivotal role in animal growth. In the foreseeable future the current legislation and the official monitoring plans may be implemented and broaden, to focus and assess limits for upcoming matrices, and to ensure feed and food safety.

Comparative Proteomic Analysis of Bacillus subtilis and Aspergillus niger in Black Soldier Fly Co-Fermentation

Black soldier fly larvae have gained popularity as an organic waste bio-conversional tool and fodder protein replacement in recent decades. It can consume all kinds of animal feces, kitchen waste and agricultural waste with great efficiency and transform them into high-value insect protein, fatty acids, and amino acids, which makes the larva a good substitute for costly fish meal and bean pulp in animal diets. However, excess chitin in the larva skin limits its application as an animal feed additive, consequently, employing fermentation with zymocytes to remove the chitin is necessary. In this study, we raised black soldier fly larvae (BSFL) with different carbon sources, such as chicken feces, straws and glucose, and examined the growth condition; we applied Bacillus subtilis and Aspergillus niger to co-ferment BSFL paste to analyze its nutrition changes. Data revealed that among the four kinds of cultures, the body weight of the corn powder group increased most rapidly; the wood chip group was the most underweight; however, it increased faster than others before day 4, and contained the least fat. Label-free quantitative proteomic analysis revealed that the expression of multiple enzymes from B. subtilis and A. niger involved in polysaccharide hydrolysis, amino acid biosynthesis and fatty acid metabolism, such as peptidase of S8 family, maltogenic α-amylase, oligo-1,6-glucosidase and lysophospholipase like protein changed significantly compared to the control group. Production detection showed that free amino acids, acid-soluble proteins, and short-chain fatty acids increased after fermentation; 13 out of 17 amino acids were increased and total free amino acids were increased from 0.08 g/100 g to 0.3 g/100 g; organic acids increased by 4.81 to 17 fold through fermentation, respectively; the actual protein content declined from 3.03 g/100 g to 1.81 g/100 g, the peptide content increased from 1.3 g/100 g to 2.46 g/100 g, the chitin degradation rate was 40.3%, and fat decreased 30% (p < 0.05). These findings might provide important information for future applications of black soldier fly larvae in different carbon waste recycling measures and material for animal feed/organic fertilizer after fermentation.

Enrichment and speciation changes of Cu and Cd in black soldier fly (Hermetia illucens) larval compost and their effects on larval growth performance

Municipal sludge (MS), rainwater sludge (RS), and kitchen waste (KW) were used as nutritional supplements for black soldier fly larvae (BSFL). Cd (52.3 %) was more easily assimilated in the BSFL body than Cu (34.8 %). After biotransformation in BSFL, the weak acid-soluble fraction (F1) of Cu and Cd increased by an average of 29.0 % and 42.7 %, respectively, whereas the reducible fraction (F2) of Cu and Cd decreased by an average of 13.8 % and 56.4 %, respectively, in the BSFL sand (BSFL feces and waste residues). A significant correlation (P < 0.01) was found between pH and the speciation of Cu and Cd. The abundance of Bacteroides had a positive correlation (P < 0.05) with the F1 of Cu, an extremely significant negative correlation (P < 0.001) with the F2 of Cd, and an extremely significant positive correlation with the F1 of Cd (P < 0.001). In addition, Cu and Cd exposures significantly (P < 0.01) reduced larval weight by 67.7 % and 45.3 %, respectively, pupation rate by 46.3 % and 26.5 %, respectively, and eclosion rate by 35.5 % and 33.4 %, respectively. Exposure to high concentrations of Cu and Cd also prolonged the development cycle (1-12 days) of BSFL and led to the failure of BSFL to complete their metamorphosis.

Soluble Extracellular Polymeric Substances Produced by Parachlorella kessleri and Chlorella vulgaris: Biochemical Characterization and Assessment of Their Cadmium and Lead Sorption Abilities

In the present study, the potential of lead and cadmium removal by the extracellular polymeric substances (EPS) produced from Parachlorella kessleri and Chlorella vulgaris were investigated. Carbohydrates were the dominant components of EPS from both analyzed species. The contents of reducing sugars, uronic acids, and amino acids were higher in EPS synthesized by C. vulgaris than in EPS from P. kessleri. The analysis of the monosaccharide composition showed the presence of rhamnose, mannose and galactose in the EPS obtained from both species. The ICP-OES (inductively coupled plasma optical emission spectrometry) analyses demonstrated that C. vulgaris EPS showed higher sorption capacity in comparison to P. kessleri EPS. The sorption capacity of C. vulgaris EPS increased with the increase in the amount of metal ions. P. kessleri EPS had a maximum sorption capacity in the presence of 100 mg/L of metal ions. The FTIR analysis demonstrated that the carboxyl, hydroxyl, and carbonyl groups of EPS play a key role in the interactions with metal ions. The present study showed C. vulgaris EPS can be used as a biosorbent in bioremediation processes due to its biochemical composition, the presence of significant amounts of negatively charged uronic acids, and higher sorption capacity.

Nutritional Composition of Black Soldier Fly Larvae (Hermetia illucens L.) and Its Potential Uses as Alternative Protein Sources in Animal Diets: A Review

The rapidly growing population has increased demand for protein quantities and, following a shortage of plant-based feed protein sources and the prohibition of animal-based feed protein, has forced the search for new sources of protein. Therefore, humans have turned their attention to edible insects. Black soldier fly larvae (BSFL) (Hermetia illucens L.) are rich in nutrients such as fat, protein and high-quality amino acids and minerals, making them a good source of protein. Furthermore, BSFL are easily reared and propagated on any nutrient substrate such as plant residues, animal manure and waste, food scraps, agricultural byproducts, or straw. Although BSFL cannot completely replace soybean meal in poultry diets, supplementation of less than 20% has no negative impact on chicken growth performance, biochemical indicators and meat quality. In pig studies, although BSFL supplementation did not have any negative effect on growth performance and meat quality, the feed conversion ratio (FCR) was reduced. There is obviously less research on the feeding of BSFL in pigs than in poultry, particularly in relation to weaning piglets and fattening pigs; further research is needed on the supplementation level of sows. Moreover, it has not been found that BSFL are used in ruminants, and the next phase of research could therefore study them. The use of BSFL in animal feed presents some challenges in terms of cost, availability and legal and consumer acceptance. However, this should be considered in the context of the current shortage of protein feed and the nutritional value of BSFL, which has important research significance in animal production.

Toxic Effects of Industrial Flocculants Addition on Bioconversion of Black Soldier Fly Larvae (Hermetia illucens L.)

Simple Summary

The black soldier fly (BSF) is a saprophagous insect that has been applied to organic waste management while providing high-quality insect protein. Flocculants are widely present in organic wastes that could be treated by black soldier fly larvae (BSFL), such as food wastes, municipal sludge, and cyanobacteria sludge. This study investigated the effect of flocculants on bioconversion of BSFL. The results showed that the addition of flocculant affected the bioconversion efficiency and nutritional composition of BSFL. The relative abundance of bacterial genera related to lipid metabolism decreased with increasing flocculant concentrations while disease-related taxa increased in relative abundance. This study could serve as a reference for related research and applications in the future.

Abstract

Black soldier fly is a saprophagous insect that has been widely reported in recent years due to its excellent performance in bioremediation. Due to the widespread presence of flocculants in the organic waste treated by black soldier fly larvae, this study aimed to evaluate the potential impacts and risks of flocculant addition (a combination of poly aluminum chloride and polyacrylamide with the ratio of 50:1). Results showed that the growth and weight of BSFL in the high-exposure groups (≥200 mg/L) were inhibited. The bioaccumulation of aluminum (Al) in larvae was estimated, and the proportions of different Al forms in the frass from high to low were the residual state (41.38% to 67.92%), water-soluble state (16.88% to 37.03%), acid-soluble state (8.45% to 18.72%), and alkali-soluble state (3.38% to 5.14%). The relative abundance of bacterial genera related to lipid metabolism decreased with increasing flocculant concentrations while disease-related taxa increased in relative abundance. The results serve as a reference for subsequent research and application of the treatment of flocculant-contaminated waste by BSFL.

Insects in Pet Food Industry-Hope or Threat?

Due to the increasing global population, the world cannot currently support the well-known techniques of food production due to their harmful effects on land use, water consumption, and greenhouse gas emissions. The key answer is a solution based on the use of edible insects. They have always been present in the diet of animals. They are characterized by a very good nutritional value (e.g., high protein content and contents of essential amino acids and fatty acids, including lauric acid), and products with them receive positive results in palatability tests. Despite the existing literature data on the benefits of the use of insects as a protein source, their acceptance by consumers and animal caregivers remains problematic. In spite of the many advantages of using insects in pet food, it is necessary to analyze the risk of adverse food reactions, including allergic reactions that may be caused by insect consumption. Other hazards relate to the contamination of insects. For example, they can be contaminated with anthropogenic factors during breeding, packaging, cooking, or feeding. These contaminants include the presence of bacteria, mold fungi, mycotoxins, and heavy metals. However, insects can be used in the pet food industry. This is supported by the evolutionary adaptation of their wild ancestors to the eating of insects in the natural environment. The chemical composition of insects also corresponds to the nutritional requirements of dogs. It should be borne in mind that diets containing insect and their effects on animals require careful analysis. The aim of this article is to discuss the nutritional value of insects and their possible applications in the nutrition of companion animals, especially dogs.

Drying of Food Waste for Potential Use as Animal Feed

A considerable part of food is wasted, causing investment capital loss as well as environmental pollution and health problems in humans. Indirect solar drying was applied to test the potential of drying and reusing this waste as a component of animal feed. The effect of weather changes on drying kinetics and the effective diffusion coefficient, dried feed nutritional composition, and microbiological analysis of the dried product were investigated. A convective laboratory dryer was used as a reference method. Weather conditions have a crucial effect on the use of solar drying; one sunny day with appropriate conditions can reduce the water activity of food waste to below 0.3 and moisture content to below 6%. Much better fitting of experimental and model drying curves was achieved considering sample shrinkage, applying a more complex solution of Fick’s second law combined with an optimization procedure. The studied food waste had a good combination of nutrients, such as protein, fat, and carbohydrates; however, the amount of protein in the dried food waste was found to be lower than that in regular feed, and therefore, adding a protein source is recommended. Autoclaving of fresh samples reduced the total microbial counts of dried samples by more than 50%.

New Eco-Sustainable Feed in Aquaculture: Influence of Insect-Based Diets on the Content of Potentially Toxic Elements in the Experimental Model Zebrafish (Danio rerio)

According to the concept of circular economy, insects represent good candidates as aquafeed ingredients. Nevertheless, there are some potential chemical risks linked with insect consumption. In this study, we reared the teleost Danio rerio, used as an experimental model, with five experimental diets characterized by increasing levels (0%, 25%, 50%, 75%, and 100%) of full-fat Hermetia illucens (Hi) prepupae, substituting for fish meal (FM) and fish oil (FO). We investigated the presence of potentially toxic elements (PTEs) Cd, Pb, Ni, As, and Hg in larval (20 days), juvenile (2 months), and adult (6 months) fish. Quantitative determinations of Cd, Pb, Ni, and As were made with an atomic absorption spectrometer; the total mercury content was determined by a direct mercury analyzer. The substitution of FM and FO with Hermetia illucens meal led to a reduction in the content of some PTEs, such as Pb, As, and Ni, in fishfeed, leading to concentrations below the legal limit of undesirable substances in animal feed. By increasing the Hi meal dietary content, we observed in the Danio rerio specimens an increase in Cd, Pb, and Ni content and a reduction in As content for all life stages. Moreover, a general increase in the content of Cd, Pb, Hg, and Ni from larvae to juvenile was measured, while the shift of Danio rerio from the juvenile to the adult stage involved a significant increase in the content of Pb, Hg, and Ni. Larvae had a reduced ability to bioaccumulate metal(loid)s compared to juveniles and adults. In conclusion, the content of PTEs in Danio rerio is influenced both by the type of diet administered and by the life stage of the animal itself. This research demonstrates the possibility of using Hi prepupae as an aquafeed ingredient without exposing fish to a chemical risk and, in perspective, allows applying these eco-sustainable diets for the breeding of edible fish species, without endangering human health.

A Comprehensive Method for the Evaluation of Hermetia illucens Egg Quality Parameters: Implications and Influence Factors

The significant momentum received by Hermetia illucens as a worldwide species is due to its biological traits and large applicability in scientific research, environmental entomoremediation, insect meal production, and for biodiesel yield. The aim of this research is to develop a method for the preparation and precise egg counting of the H. illucens egg clutch, as well as an accurate technique for evaluating egg biometric parameters. The precise proposed method for egg preparation and counting consists in dispersing the eggs clutch under a stereo microscope and counting the eggs on a photographic capture using the Clickmaster software. Five solution types were used to disperse the egg clutches: glycerin 50%, ethanol 70%, ethanol 80%, physiological serum 0.9% and purified water. The efficiency of the estimation method for eggs number evaluation was also tested by using the estimated egg weight as a conversion factor. The biometric parameters of single eggs (length and width) were determined using the free Toupview software. The precise method of egg preparation and counting allows for the registration of the eggs number manually identified by the operator. The appropriate dispersion solutions were glycerin 50% and ethanol 70%. The method has an error of 1.4 eggs for each 500 counted eggs, thus an accuracy of over 99.4%. The eggs number estimation method is not applicable without significant errors, the accuracy being less than 32%, due to egg heterogeneity in the clutch. Biometric parameters (length and width) are positively correlated with egg weight (r = 0.759) and with the number of eggs in the clutch (r = 0.645). In conclusion, the results clearly suggest the method of egg preparation and precise counting for an accurate evaluation of quality parameters of the H. illucens clutches, as well as the technique for evaluating egg biometric parameters.

Research trend analysis of composting based on Web of Science database

Bibliometric analysis was used in this study for the quantitative evaluation of current research trends on composting. The research articles indexed from the Science Citation Index-Expanded in Web of Science database published from 2000 to 2019 were investigated. The USA, China and Spain were the top three countries considering the number of papers. Amongst the research institutes, CSIC of Spain, Chinese Academy of Sciences and Agriculture & Agri-Food Canada ranked the top three in total publication amount. Journals that published a significant number of literature regarding topics of composting included Environmental Sciences & Ecology, Agriculture and Engineering. In terms of research content, keywords such as heavy metal, heavy metal and biodegradation appeared frequently. In addition, the analysis of keywords revealed the following research hotspots in future studies: investigation of heavy metal passivator, optimisation of composting conditioner, development of all kinds of microorganisms, rational management of the composting process and improvement of solid waste life cycle assessment. To some extent, it helps to understand the current global status and trends of the related research.

Food Safety of Consuming Black Soldier Fly (Hermetia illucens) Larvae: Microbial, Heavy Metal and Cross-Reactive Allergen Risks

Black soldier fly (Hermetia illucens) larvae (BSFL) are a promising, sustainable source of nutrients, however, there is limited knowledge regarding the food safety of consuming BSFL. This study determined the safety of consuming BSFL for direct human consumption in terms of microbial, heavy metal and allergen content. Microbial counts were determined using ISO (International Organization for Standardization) methods, heavy metals were determined using inductively coupled plasma mass spectrometry and allergens were determined via Orbitrap mass spectrometry and ELISA (enzyme-linked immunosorbent assay) kits. Feed and killing method influenced the presence of Bacillus cereus (p = 0.011), and only the killing method influenced Escherichia coli (p < 0.00) and total viable count (TVC) (p < 0.00). Blanching resulted in a 3-log reduction in E. coli and a 3.4 log reduction in the TVC counts. Salmonella spp. and Listeria spp. were not detected in the BSFL samples. Heavy metals were detected although they were below maximum legal limits. Cross-reactive allergens, tropomyosin and arginine kinase, were detected in the BSFL samples, although the clinical significance requires research. The feed fed to the BSFL and blanching were found to influence the safety of consuming BSFL, highlighting the importance of incorporating sufficient decontamination steps, such as blanching, to ensure food safety.

A New Approach to Quantifying Bioaccumulation of Elements in Biological Processes

Simple Summary

The bioaccumulation of elements (e.g., heavy metals) in living organisms (e.g., animals) is vitally important from at least two points of view: the growth and development of the organisms themselves and remediation of the polluted environment. So far, bioaccumulation has been characterized by the bioaccumulation factor (BAF), which is the ratio between the concentration of elements in the organism to the concentration in the matrix (water, soil, etc.). This factor is a good measure of bioaccumulation in ecosystems in which an organism lives from the beginning of their lives to the moment of investigation. However, especially in laboratory experiments, when organisms at a given stage of development are introduced to the system and contain some non-zero concentration of an element, the BAF can lead to misinterpretation. Therefore, we propose a new measure called the bioaccumulation index (BAI), which is the relative increase in the concentration of a given element in the organism to its initial concentration after the experiment. We proved, on the basis of data published by other authors, that the BAI was much more valid for the interpretation of bioaccumulation in these cases.

Abstract

Bioaccumulation, expressed as the bioaccumulation factor (BAF), is a phenomenon widely investigated in the natural environment and at laboratory scale. However, the BAF is more suitable for ecological studies, while in small-scale experiments it has limitations, which are discussed in this article. We propose a new indicator, the bioaccumulation index (BAI). The BAI takes into account the initial load of test elements, which are added to the experimental system together with the biomass of the organism. This offers the opportunity to explore the phenomena related to the bioaccumulation and, contrary to the BAF, can also reveal the dilution of element concentration in the organism. The BAF can overestimate bioaccumulation, and in an extremal situation, when the dilution of element concentration during organism growth occurs, the BAF may produce completely opposite results to the BAI. In one of the examples presented in this work (Tschirner and Simon, 2015), the concentration of phosphorous in fly larvae was lower after the experiment than in the younger larvae before the experiment. Because the phosphorous concentration in the feed was low, the BAF indicated a high bioaccumulation of this element (BAF = 14.85). In contrast, the BAI showed element dilution, which is a more realistic situation (BAI = −0.32). By taking more data into account, the BAI seems to be more valid in determining bioaccumulation, especially in the context of entomoremediation research.

Transformation of pig manure by passage through the gut of black soldier fly larvae (Hermetia illucens): Metal speciation, potential pathogens and metal-related functional profiling

Black soldier fly larvae (BSFL) have great potential in livestock manure disposal. However, the changes in metal speciation, microbial communities, potential pathogens during the manure transformation process by BSFL is still largely uncharacterized, as well as the underlying metal tolerance mechanism of larval gut microbiome. Here we used BSFL to convert pig manure (PM) into larval feces (BF), and investigated the metal and microbial changes in the conversion process. Physicochemical parameters (e.g. pH, electrical conductivity, total nitrogen, total phosphorus and total potassium) in PM were significantly altered compared to BF. After conversion, less than 10% of Cu and Zn were accumulated in larval bodies. The bioavailable fraction of Cu (88.3%-86.2%) and Zn (80.6%-82.3%) occupied as the primary form in PM and BF. Genera Enterococcus, Clostridium_sensu_stricto_1, Terrisporobacter and Romboutsia were substantially enriched in the final BSFL gut (GF) compared with initial gut (GI). BSFL transformation substantially reduced pathogen abundances (decreased by 89%) derived from pig manure. Functional genes involved in metal homeostasis and resistance (e.g. CutC, pcoC, cusR, zurR and zntB) were obviously strengthened (by 2.3-7.7 folds) in GF than in GI, which might partly explain the metal tolerance ability of BSFL during the livestock manure transformation process.

Occurrence of Antibiotic Resistance Genes in Hermetia illucens Larvae Fed Coffee Silverskin Enriched with Schizochytrium limacinum or Isochrysis galbana Microalgae

Hermetia illucens larvae are among the most promising insects for use as food or feed ingredients due to their ability to convert organic waste into biomass with high-quality proteins. In this novel food or feed source, the absence of antibiotic-resistant bacteria and their antibiotic resistance (AR) genes, which could be horizontally transferred to animal or human pathogens through the food chain, must be guaranteed. This study was conducted to enhance the extremely scarce knowledge on the occurrence of AR genes conferring resistance to the main classes of antibiotics in a rearing chain of H. illucens larvae and how they were affected by rearing substrates based on coffee silverskin supplemented with increasing percentages of Schizochytrium limacinum or Isochrysis galbana microalgae. Overall, the PCR and nested PCR assays showed a high prevalence of tetracycline resistance genes. No significant effect of rearing substrates on the distribution of the AR genes in the H. illucens larvae was observed. In contrast, the frass samples were characterized by a significant accumulation of AR genes, and this phenomenon was particularly evident for the samples collected after rearing H. illucens larvae on substrates supplemented with high percentages (>20%) of I. galbana. The latter finding indicates potential safety concerns in reusing frass in agriculture.

Production and Optimization of Hermetia illucens (L.) Larvae Reared on Food Waste and Utilized as Feed Ingredient

The feed sector requires new sustainable sources of protein, and at the same time better waste management practices are required to decrease and upcycle post-consumers’ food waste (catering and organic household waste), which is currently used for energy production or discharged as waste. The production of Hermetia illucens larvae (L.) (BSFL) was conducted in 15 batches at pilot scale. Furthermore, a feeding strategy experiment was conducted to optimize feedings and decrease handling, followed by a digestibility study for assessing the applicability of BSFL as a feed ingredient. About 190 kg of food waste was used to produce 79 kg of BSFL. The bioconversion of food waste into BSFL was found to be highly efficient, with feed conversion rate (FCR) values ranging between 1.7 and 3.6, when assessed on dry matter. The feeding experiment showed similar BSFL and insect frass production as well as similar FCR, revealing that a decrease in handling can be obtained if two feeding episodes are used. The digestibility of protein and fat was high at 86.2 and 90.4% and revealed that BSFL meal can be successfully used as a protein and fat source in feed for carnivore animals outside the food chain (e.g., pet food).

Revisiting the concept of entomotoxicology

Until now, the term entomotoxicology has only been used in medico-legal sciences. However, entomotoxicology as a whole has a much wider scope and forensic entomotoxicology is just one of its branches. Based on the literature a wider definition of the term is presented. Today, we can distinguish two major branches of entomotoxicology: 1) Forensic entomotoxicology, which uses the insects as evidence of the presence of xenobiotics in decomposing tissue during an investigation and 2) Environmental entomotoxicology, which uses the insects as bioindicators of environmental pollution in non-criminal circumstances. While forensic entomotoxicology is a relatively new discipline, research in environmental entomotoxicology began as far back as the 1920s. A review of the work in entomotoxicology from the last 6 years is presented, covering several interesting new trends. This article aims to redefine entomotoxicology, which should increase awareness to bring more collaborations and multidisciplinary between related scientific fields.

Larvae Mediated Valorization of Industrial, Agriculture and Food Wastes: Biorefinery Concept through Bioconversion, Processes, Procedures, and Products

Each year, the food supply chain produces more than 1.3 billion tons of food and agricultural waste, which poses serious environmental problems. The loss of the massive quantity of secondary and primary metabolites retrievable from this resource is a significant concern. What if there is a global solution that caters to the numerous problems arising due to the humongous volume of waste biomass generated in every part of the world? Insects, the tiny creatures that thrive in decaying organic matter, which can concentrate the nutrients present in dilute quantities in a variety of by-products, are an economically viable option. The bioconversion and nutritional upcycling of waste biomass with insects yield high-value products such as protein, lipids, chitin and frass. Insect-derived proteins can replace conventional protein sources in feed formulations. Notably, the ability of the black soldier fly (BSF) or Hermetia illucens to grow on diverse substrates such as agri-food industry side streams and other organic waste proves advantageous. However, the data on industrial-scale extraction, fractionation techniques and biorefinery schemes for screening the nutritional potential of BSF are scarce. This review attempts to break down every facet of insect processing and analyze the processing methods of BSF, and the functional properties of nutrients obtained thereof.

Liminal presence of exo-microbes inoculating coconut endosperm waste to enhance black soldier fly larval protein and lipid

The anaerobic decomposition of coconut endosperm waste (CEW), residue derived from cooking, has been insidiously spewing greenhouse gasses. Thus, the bioconversion of CEW via in situ fermentation by exo-microbes from commercial Rid-X and subsequent valorization by black soldier fly larvae (BSFL) was the primary objective of the current study to gain sustainable larval lipid and protein. Accordingly, various concentrations of exo-microbes were separately homogenized with CEW to perform fermentation amidst feeding to BSFL. It was found that 2.50% of exo-microbes was the threshold amount entailed to assuage competition between exo-microbes and BSFL for common nutrients. The presence of remnant nutrients exuded from the fermentation using 2.50% of exo-microbes was confirmed to promote BSFL growth measured as maximum larval weight gained and growth rate. Although the BSFL could accumulate the highest protein (16 mg/larva) upon feeding with CEW containing 2.50% of exo-microbes, more lipid (13 mg/larva) was stored in employing 0.10% of exo-microbes because of minimum loss to metabolic processes while prolonging the BSFL in its 5th instar stage.