Growth efficiency, intestinal biology, and nutrient utilization and requirements of black soldier fly (Hermetia illucens) larvae compared to monogastric livestock species: a review

On-site sanitation solutions are an economically feasible method of improving sanitation, and for reducing the burden of diarrhoeal diseases, in low- and middle-income countries. However, suitable faecal sludge management (FSM) solutions are severely lacking in these countries. Black solider fly larvae (BSFL) efficiently reduce food-waste and animal manure, and produce valuable prepupae, high in protein and fat, supporting investigation into a novel BSFL FSM method. The aim of this study was to determine the feasibility of using BSFL as a FSM method, by evaluating their faecal matter reduction (FMR), and prepupal production capacity, when reared on FS under different conditions.
\nBlack soldier fly larvae were found to develop successfully on fresh human faeces, effectively reducing waste and converting it to prepupal biomass. A survey of pit latrines in South Africa found physical and chemical characteristics of faecal sludge (FS) similar to previous studies in countries requiring novel FSM methods, with characteristics falling within a range suitable for BSFL development. Key rearing parameters, moisture content, feeding rate, and larval density, significantly influence FMR and prepupal production of BSFL reared on “top layer” homogenised FS. Black soldier fly larvae were found to effectively reduce FS from a variety of depths, each with a range of physical and chemical characteristics, and produce prepupae with nutritious values comparable to previous research, excepting crude fats. The study also demonstrated that reported cleaning chemicals in FS do not affect BSFL mortality at manufacturer recommended, or user reported concentrations.
\nIt is proposed that the use of a novel BSFL FSM method is an economically feasible method of improving sanitation in low- and middle-income countries, and may help reduce the burden of diarrhoeal diseases.

Purpose Compost production technology and use are known among Ghanaians farmers. However, the long composting period averaging three months has had adverse effect on adoption. The black soldier fly (Hermetia illucens) larvae (BSFL) feed voraciously and breaks down organic wastes fast. Addition of rice husk biochar (RHB) neutralises acidity and aerates the compost. Combined application of BSFL and RHB to feedstocks could therefore reduce composting period and improve compost quality. Method Two studies were conducted with market crop waste (MCW) as feedstock. Firstly, feedstocks at two particle sizes (x < 5 mm and 5 mm < x >10 mm), with and without BSFL were evaluated to determine degradability, chemical content of the degraded residue and to select appropriate feedstock size ideal for composting. Secondly, the selected feedstocks size of between 5 mm and 10 mm were inoculated with or without BSFL and RHB of 0%, 5% 10% and 15% added. Composting trials were conducted in barrels inclined at 30o to facilitate drainage. Physicochemical and biological parameters of feedstock were monitored until maturity. Results Degradability of MCW by BSFL was feedstock specific rather than feedstock size. Inoculation of BSFL and biochar addition reduced composting period from 76 to 45 days. Biochar addition at 15% increased P availability to 1882 mg kg-1 but reduced total N to 10.5 g kg-1. E coli levels decreased in the BSFL-biochar composts to acceptable limits. Conclusion Composting MCW with BSFL and biochar reduced composting period and improved compost quality.

Black Soldier Fly larvae (BSFL) are insect larvae that can be utilized as a bioconversion agent. In this research, BSFL larvae were used as a bioconversion agent on ground banana peels (GBP) and chicken feed (CF). This research determined the effect of GBP as diet on larval weight increment (LWI), larval development time (LD), and the ability of BSFL to convert the GBP based on Approximate Digestibility (AD), Weight Reduction Index (WRI), and Efficiency of Conversion of Digested food (ECD). The study used 10-day-old BSFLs, which were fed with constant food amount of CF and GBP at levels of 50 g/day and different numbers of larvae (100, 200 and 300) were utilized. The experiment was arranged as a randomized complete block design, with four replicates for each diet. Results showed that BSFL fed with CF has a better LWI (ranging between 1.33±0.38 g/d to 1.38±0.39 g/d). The LD results show that CF fed larvae resulted in faster development time (12±0.000001 days) compared to GBP fed larvae (30±0.14 days). The study also found that a greater number of larvae resulted in a more efficient bioconversion activity, where 300 larvae resulted in higher values for key parameters such AD (%), WRI (%) and ECD (%), compared to 200 and 100 larvae. The correlation analysis revealed no significant and weak negative relationship between the number of larvae and LD that were fed with CF (R 2 =-0.237, P &gt;0.05). Similarly, when fed with GBP, there was no significant and weak positive relationship (R 2 =0.118, P &gt;0.05) between the number of larvae and LD. Conversely, there was a highly significant strong positive relationship between the number of larvae with ECD when fed with CF (R 2 =0.946, P &lt;0.001) and GBP (R 2 =0.946, P &lt;0.001). In conclusion, the findings indicate that BSFLs fed with GBP have low WRI (%) and ECD (%).

Two low-toxic Klebsiella pneumoniae strains from gut of black soldier fly Hermetia illucens are multi-resistance to sulfonamides and cadmium

Efforts to recycle organic wastes using black soldier fly (BSF) Hermetia illucens into high-nutrient biomass that constitutes a sustainable fat (biodiesel) and high-quality protein ingredient in animal feeds have recently gained momentum worldwide. However, there is little information on the most suitable rearing conditions for growth, development and survivorship of these flies, which is a prerequisite for mass production technologies. We evaluated the physiological requirements for growth and reproduction of H. illucens on two diets [spent grains supplemented with brewers' yeast (D1) and un-supplemented (D2)]. Development rates at nine constant temperatures (10 - 42°C) were fitted to temperature-dependent linear and non-linear day-degree models. Thereafter, life history table parameters were determined within a range of favourable temperatures. The thermal maximum (TM) estimates for larval, pre-pupal and pupal development using non-linear model ranged between 37.2 ± 0.3 and 44.0 ± 2.3°C. The non-linear and linear day-degree model estimations of lower developmental temperature threshold for larvae were 11.7 ± 0.9 and 12.3 ± 1.4 °C for D1, and 10.4 ± 1.7 and 11.7 ± 3.0 °C for D2, respectively. The estimated thermal constant of immature life stages development of BSF was higher for the larval stage (250±25 DD for D1 and 333±51 for D2) than the other stages evaluated. Final larval wet weight was higher on D1 compared to D2. The population growth rate was most favourable at 30-degree celsius (°C) with higher intrinsic rate of natural increase (r_m=0.127 for D1 and 0.122 for D2) and shorter doubling time (5.5 days for D1 and 5.7 days for D2) compared to the other temperatures. These results are valuable for the optimization of commercial mass rearing procedures of BSF under various environmental conditions and prediction of population dynamics patterns using computer simulation models.

Treatment of landfill leachate by black soldier fly (Hermetia illucens L.) larvae and the changes of intestinal microbial community

Simple SummaryIn recent years, farming the black soldier fly (BSF) Hermetia illucens (L.) (Diptera: Stratiomydiae) has gained popularity across the globe due to its usefulness mainly in animal feed production and waste management. The short cycle time taken to rear the BSF and the high protein content present in its larvae makes it a suitable source of feed for a variety of animals (e.g., poultry, fish, and pigs); the livestock bred as food for humans. However, despite the farming of black soldier fly larvae (BSFL) as a source of feed, its production levels are low and do not meet the existing market demand. This study explored data science and machine learning modeling approaches to discern optimal rearing conditions for improved BSFL farming. The random forest regressor machine learning algorithm gave the best prediction results. The algorithm also ranked the variables that contributed most to the prediction of the expected larvae weight. Given the studied rearing conditions, the prediction algorithm can discern and predict the expected weight of BSFL to be harvested. Tuning the production system parameters according to the order of the ranked parameters can further optimize the production of BSFL. BSFL are a source of feed for the animals that are a source of food for humans; therefore, this research contributes to alleviating food insecurity.As the world population continues to grow, there is a need to come up with alternative sources of feed and food to combat the existing challenge of food insecurity across the globe. The use of insects, particularly the black soldier fly (BSF) Hermetia illucens (L.) (Diptera: Stratiomydiae), as a source of feed stands out due to its sustainability and reliability. Black soldier fly larvae (BSFL) have the ability to convert organic substrates to high-quality biomass rich in protein for animal feed. They can also produce biodiesel and bioplastic and have high biotechnological and medical potential. However, current BSFL production is low to meet the industry’s needs. This study used machine learning modeling approaches to discern optimal rearing conditions for improved BSF farming. The input variables studied include the cycle time in each rearing phase (i.e., the rearing period in each phase), feed formulation type, length of the beds (i.e, rearing platforms) at each phase, amount of young larvae added in the first phase, purity score (i.e, percentage of BSFL after separating from the substrate), feed depth, and the feeding rate. The output/target variable was the mass of wet larvae harvested (kg per meter) at the end of the rearing cycle. This data was trained on supervised machine learning algorithms. From the trained models, the random forest regressor presented the best root mean squared error (RMSE) of 2.91 and an R-squared value of 80.9%, implying that the model can be used to effectively monitor and predict the expected weight of BSFL to be harvested at the end of the rearing process. The results established that the top five ranked important features that inform optimal production are the length of the beds, feed formulation used, the average number of young larvae loaded in each bed, feed depth, and cycle time. Therefore, in that priority, it is expected that tuning the mentioned parameters to fall within the required levels would result in an increased mass of BSFL harvest. These data science and machine learning techniques can be adopted to understand rearing conditions and optimize the production/farming of BSF as a source of feed for animals e.g., fish, pigs, poultry, etc. A high production of these animals guarantees more food for humans, thus reducing food insecurity.

Wild black soldier flies, Hermetia illucens (Diptera: Stratiomyidae): Seasonal availability and life history traits in two common organic streams in Bangladesh

The growth of the climbing perch Anabas testudineus reared on lower protein feeds with the replacement of fishmeal (FM) by prepupae of the black soldier fly (BSF) Hermetia illucens was examined. Three different feeds were prepared: control feed (treatment 1; T1) with only FM as a source of animal protein [32.5% crude protein; CP]; lower protein feed (T2) with both FM and BSF (30.0%); lowest protein feed (T3) with only BSF prepupae as a source of animal protein (25.0%). After 123 days of rearing, survival rates were ca. 82% in all treatments. The final weights in T2 and T3 (84–92 g/fish) were comparable to that in T1 (ca. 85 g/fish) despite the lower protein levels of feeds in T2/T3. Similarly, CP levels of fish at harvest in T2/T3 were comparable to T1 (17–18%), while the crude fat level in T3 (ca. 14%) was significantly greater than in T1/T2 (ca. 12%). The level of ash in T3 (ca. 4.1%) was significantly lower than in T1/T2 (5.4–5.7%). The protein efficiency ratio in T3 (ca. 1.3) was significantly greater than in T1/T2 (0.9–1.1), and the protein retention in T3 (ca. 21.9) was significantly greater than in T1 (ca. 16.4). Similar final weights observed between T1 and T2/T3 suggested that BSF protein can be better assimilated by climbing perch than FM. The results suggest that BSF prepupae are an efficient substitute for FM in climbing perch feed, and potentially allow for a reduction of feed protein levels.

Characteristics of intestinal microbial communities and occurrence of antibiotic resistance genes during degradation of antibiotic mycelial residues by black soldier fly (Hermetia illucens L.) larvae.

Laboratory experiments on predatory aquatic insects have various practical challenges, including high nutritional demands of fresh prey. Ideally, predatory insects are reared with live prey that are easy to cultivate in a laboratory environment, low-cost, rich in nutrients, and easily accessible. Here, we assess whether the black soldier fly (BSF) Hermetia illucens larvae and adults are suitable feed for major aquatic insect groups with distinct trophic niches (Odonata, Coleoptera, Hemiptera, and Megaloptera). We first determined the size overlap between BSF larvae and major aquatic insect groups using existing databases of body size. We then experimentally assessed whether BSF larvae: (1) are consumed by different groups of predators, (2) can survive prolonged periods underwater, and (3) are selected based on body size. We found that the body size of BSF larvae overlaps with most insect groups, with smaller larval instars showing the highest overlap. Our feeding experiment showed that all predatory insect groups consumed BSF larvae and could survive under a strict BSF diet for at least a few weeks. Insect floaters (water striders) and divers (backswimmers and diving beetles) consumed BSF adults regularly. BSF larvae sunk underwater and repeatedly performed undulating movements, making them detectable to predators. BSF larvae can survive underwater for extended periods (1–6 days), with larger instars surviving longer. For sit-and-wait predators such as odonates (dragonflies and damselflies), larvae were more likely to consume smaller BSF larvae. Our observed behavioural and physiological characteristics of the BSF suggest that it is a promising complementary feed for various aquatic insects.

IntroductionThis study examines the optimum conversion of Wuzhishan pig manure by Black Soldier Fly Larvae (BSFL) at various phases of development, as well as the impact of gut microbiota on conversion efficiency.Method and resultsIn terms of conversion efficiency, BSFL outperformed the growing pig stage (GP) group, with significantly higher survival rates (96.75%), fresh weight (0.23 g), and larval conversion rate (19.96%) compared to the other groups. Notably, the GP group showed significant dry matter reductions (43.27%) and improved feed conversion rates (2.17). Nutritional composition varied, with the GP group having a lower organic carbon content. High throughput 16S rRNA sequencing revealed unique profiles, with the GP group exhibiting an excess of Lactobacillus and Clostridium. Promising cellulose-degrading bacteria in pig manure and BSFL intestines, including Bacillus cereus and Bacillus subtilis, showed superior cellulose degradation capabilities. The synergy of these thermophilic bacteria with BSFL greatly increased conversion efficiency. The BSFL1-10 group demonstrated high growth and conversion efficiency under specific conditions, with remarkable larval moisture content (71.11%), residual moisture content (63.20%), and waste reduction rate (42.28%).DiscussionThis study sheds light on the optimal stages for BSFL conversion of pig manure, gut microbiota dynamics, promising thermophilic cellulose-degrading bacteria, and the significant enhancement of efficiency through synergistic interactions. These findings hold great potential for sustainable waste management and efficient biomass conversion, contributing to environmental preservation and resource recovery.

Mealworms and black soldier fly (BSF) larvae are two of the most reared insects at an industrial scale. Both may feed on by-products from agricultural and food industries. Feed efficiency is one of the most important aspects of such processes and varies between species and feed substrates and depends on the metabolic performance of the larvae. Compared to each other, both species may hold advantageous capabilities affecting their feed efficiency, likely depending on the feed substrate. We reared mealworms and BSF larvae on a diverse selection of by-products from agricultural and food industries, quantified major metabolic rates across their life spans, and compared their performances. The type of feed substrates had stronger effects on the growth of mealworms than on black soldier fly larvae. Generally, BSF larvae were advantageous in terms of the highest maximal specific growth rate (0.50-0.77 day-1) and feed assimilation rate (0.81-1.16 day-1) and shortest development period (23-25 days) but disadvantageous in terms of metabolic maintenance cost (0.07-0.21 day-1). In mealworms, the maximal specific growth rates were 0.02-0.11 day-1, the highest feed assimilation rates were 0.16-0.37 day-1, and the development period was at least 65-93 days, while maintenance was only 0.02-0.05 day-1. In contrast to the BSF larvae, the specific maintenance rate was weight dependent in the mealworms and lowest in the largest individuals. The combined outcome of these metabolic rates resulted in an average carbon net growth efficiency, NGE*avg of 0.16-0.40 in mealworms and 0.33-0.56 in BSF larvae across their life span. It thus seems that BSF larvae are more versatile and somewhat more efficient at converting diverse feed substrates into growth than mealworms. Differences in NGE*avg affected the substrate conversion efficiencies (i.e., the ratio of the weight gain of the larvae to the reduced weight of feed substrates) and may thus impact the overall outcome of insect farming.

Due to the increase of consumption of food products by the population, especially of animal origin, the need of the livestock industry including sheep breeding for high-quality feed from an ecological point of view also increases. Recently, insects have received a lot of attention as a source of feed protein in the diet of farm animals. This is evidenced by numerous studies on the nutritional value and use of larvae of Black soldier fly (Hermetia illucens), Green-bottle fly (Lucilia Caesar), House fly (Musca domestica), meal worm (Tenebrio molitor), silkworms (Bombyx mori), and crickets (Gryllusbi maculatus) as food for farm animals. It is well known from foreign literature sources about the use of additive from silkworm pupae in the ration of sheep, as well as meal from crickets as the source of protein in the diet of lambs. The silkworm is a monophage eats in only at the caterpillar stage absorbing and accumulating the necessary nutrients and water from the mulberry leaves. The analysis of the works of foreign authors shows that the protein content in the silkworm caterpillars depending on the breed ranges from 63,02 to 67,99 %. However, the analysis of the content of the main nutrients in the section of silkworm breeds as well as the age of the caterpillars was not carried out in the works of domestic scientists. This research presents data on the nutrient content and metabolic energy in silkworm caterpillars by age depending on the breed for further development of the feed additive from silkworm biomass and its use in sheep breeding. In the course of the conducted research, the following results have been obtained. So, at the end of the 4th age on average the caterpillars have a body length of 4,5–5,0 cm, the weight of one caterpillar is 0,6–0,7 g. The largest size and weight are the caterpillars on 10 days of the 5th age; their body length on average for the studied breeds was 8,0–8,5 cm, the weight of one caterpillar was 4,5–5,5 g. The optimal stage of development of silkworm caterpillars for the production of feed additive is 10 days in the 5th age. During this period the caterpillars of the studied breeds Kavkaz-1, Kavkaz-2, Belokokonnaya-1, Belokokonnaya-2 contain protein from 62,71 to 66,55 %, fat from 14,81 to 16,95 %, fi ber from 2,36 to 2,81 %, ash 4,39–3,96 % and nitrogen-free extractive substances 9,31–15,81 % in absolutely dry matter. The highest content of nutrients and metabolic energy is allocated to the breeds Belokokonnaya-2 (protein – 66,55 %, fat – 16,95 %, metabolic energy – 20,86 MJ/kg) and Kavkaz-2 (protein – 64,10 %, fat – 15,59 %, metabolic energy – 20,24 MJ/kg).

Salah satu bentuk pengendalian sampah organik yang sekarang aktif dikembangkan adalah proses biokonversi menggunakan larva lalat tentara hitam (Hermetia illucens (Linnaeus)). Salah satu tantangan dalam pengolahan limbah organik adalah mengolah limbah organik pada lokasi penampungan limbah dengan luas terbatas. Kondisi ini menyebabkan tingginya jumlah sampah yang harus dikonversi (dikonsumsi) oleh larva. Penelitian ini dilakukan untuk mengamati kemampuan cerna dan kualitas larva yang diberi pakan berupa sayuran busuk dalam jumlah berlebih. Sampah limbah sayur pakcoy diberikan dengan jumlah 200, 300, 400, dan 500 mg/larva/hari dengan pengulangan 3 kali. Variabel yang diamati adalah laju pertumbuhan, jumlah sampah yang dapat direduksi (waste reduction index (WRI)), efisiensi pembentukan biomassa (efficiency of conversion of digested-feed [ECD]), produk yang dihasilkan (biomassa akhir), dan kandungan protein pada larva, pupa, dan dewasa. Hasil penelitian menunjukkan tidak terdapat perbedaan yang signifikan pada berat biomassa yang dipanen seiring dengan peningkatan jumlah pakan yang diberikan (one-way ANOVA, P &gt; 0,05). Peningkatan pemberian pakan secara signifikan menurunkan efisiensi proses penguraian dan proses perubahan limbah menjadi biomassa tubuh serangga (one-way ANOVA, P &lt; 0,05). Penelitian ini menghasilkan dugaan bahwa batas atas kemampuan konsumsi larva adalah pada tingkat pemberian pakan sebesar 400 mg/larva/hari. Di sisi lain, peningkatan jumlah pakan yang diberikan meningkatkan kandungan protein kasar pada biomassa dari setiap tahapan perkembangan larva.