Valorisation Potential of Using Organic Side Streams as Feed for Tenebrio molitor, Acheta domesticus and Locusta migratoria

Beyond carrots: Evaluation of gelling agents as wet feeds for Tenebrio molitor L. (Coleoptera: Tenebrionidae) larvae

Previous studies have shown that larvae of the yellow mealworm, Tenebrio molitor L. (Coleoptera: Tenebrionidae), need a source of moisture to grow and perform well. Currently, much research has been oriented towards the effect of dry feed on larval growth and performance. The effect of different wet feeds as moisture source on the performance traits of T. molitor larvae has not been thoroughly investigated yet. This study aims to investigate in laboratory trials the effect of various gelling agents (agar, carrageenans, guar gum, xanthan gum, sodium alginate, modified starch, and pectin) on the growth and performance of T. molitor larvae. A number of 50 newly emerged larvae obtained from the rearings of the LEAZ were inserted in plastic vials together with 4 g of wheat bran as dry feed. Additionally, 1 g of gelling agents was provided 3 times per week as moisture sources. Carrot slices served as control. Larval survival and weight were recorded weekly until the appearance of the first pupa. Dry feed was replenished when depleted. Our data showed that gelling agents efficiently supported the growth of T. molitor larvae, in terms of larval survival and weight, as well as feed utilization expressed as FCR. Interestingly, carrageenans seem to be the most appropriate gelling agent for T. molitor larvae rearing as it can enhance their weight and is also able to reduce their development time and their specific growth rate.

MINIstock: Model for INsect Inclusion in sustainable agriculture: USDA-ARS's research approach to advancing insect meal development and inclusion in animal diets

Animal agriculture is under pressure to increase efficiency, sustainability, and innovation to meet the demands of a rising global population while decreasing adverse environmental effects. Feed cost and availability are 2 of the biggest hurdles to sustainable production. Current diets depend on sources of grain and animal byproduct protein for essential amino acids which have limited sustainability. Insects have arisen as an attractive, sustainable alternative protein source for animal diets due to their favorable nutrient composition, low space and water requirements, and natural role in animal diets. Additionally, insects are capable of bioremediating waste streams including agricultural and food waste, manure, and plastics helping to increase their sustainability. The insect rearing industry has grown rapidly in recent years and shows great economic potential. However, state-of-the-art research is urgently needed to overcome barriers to adoption in commercial animal diets such as regulatory restrictions, production scale issues, and food safety concerns. To address this need, the USDA Agricultural Research Service "MINIstoc: Model for INsect Inclusion" project was created to bring together diverse scientists from across the world to synergistically advance insect meal production and inclusion in animal diets. Here, we provide a short review of insects as feed while describing the MINIstock project which serves as the inspiration for the Journal of Economic Entomology Special Collection "Insects as feed: sustainable solutions for food waste and animal production practices."

Novel foods, old issues: Metabarcoding revealed mislabeling in insect-based products sold by e-commerce on the EU market

Insects intended for human consumption are considered Novel Foods according to EU legislation. marketed in form of powders, bars, snacks are increasingly available on the EU market, especially on e-commerce. The commercial form and the way of distribution make IBPs particularly prone to mislabeling. Literature concerning the mislabeling occurrence in IBPs is extremely scarce. In this study, 46 processed IBPs were collected on nine EU e-commerce platforms (e-CO) to be authenticated by metabarcoding. A 200 bp region from 16S rRNA gene was used as molecular target. Sequencing data were processed using DADA2 R package, and sequences were taxonomically assigned through BLAST analysis against GenBank. Procedural blanks and positive controls were included in the analysis, and threshold values were established to filter the final data. The mislabeling rate (i. e. the mismatch between the species declared on the IBP label and the species identified by metabarcoding) was calculated. Overall, a high mislabeling rate (33.3 %) was observed, although this percentage is influenced by the e-CO platform and the insect species, with A. domesticus particularly involved. The use of species not listed in authorized Novel Food (e. g. Gryllus locorojo), and/or the partial replacement of high value species with lower value species was highlighted for the first time in processed IBPs. The presence of insect pests was also detected. Metabarcoding was confirmed as an effective tool for IBPs authentication. Also, outcomes from this study can provide useful data on the main issues involving the EU IBPs' market, that can represent an incentive to reinforce both official controls and FBO's self-controls on these poorly investigated products.

Growth Performance, Diet Digestibility, and Chemical Composition of Mealworm (Tenebrio molitor L.) Fed Agricultural By-Products

Humanity's growing demand for animal protein exceeds the capacity of traditional protein sources to support growing livestock production. Insects offer promising partial substitutes, converting low-nutritional quality materials into high-value biomass. Hence, the bioconversion ability of Tenebrio molitor larvae was assessed by using three types of agricultural by-products (broccoli by-product, tigernut pulp, and grape pomace) at different inclusion levels (0%, 25%, 50%, and 100%) in a carbohydrate-based diet. Ten diets were formulated to assess their impact on the growth, diet digestibility, and nutritional composition of the larvae. For each treatment, eight replicates were employed: five for the growth-performance-digestibility trial and three for the complementary test of uric acid determination. The growth was influenced by the type of diet administered. The broccoli by-product resulted in higher larvae weight and a better feed conversion ratio. However, diets based solely on a single by-product (100%) compromised the productivity and diet digestibility. The larvae changed their nutritional composition depending on the rearing substrate, although the amino acid profile remained consistent. In conclusion, the studied by-products have the potential for use in T. molitor rearing as part of the diet but not as the exclusive ingredients, indicating promising opportunities for using agricultural by-products in T. molitor rearing and production.

Evaluating an emerging technology-based biorefinery for edible house crickets

Introduction

Edible insects, specifically house crickets, are expected to play an important role in the future food systems due to their rich nutritional profile, low environmental impact and growing consumer acceptance as food. Their content of proteins, lipids, chitin and phenolics offer great potential for the valorization of their biomass into nutritional end products and fractions. Furthermore, emerging food processing technologies and green solvents are relevant for improving the valorization process.

Materials and methods

High pressure (HP) and ultrasound (US) processing were implemented in an insect biorefinery system, where a hexane/methanol/water solvent was used to separate fat, phenolics and a solid fraction containing proteins and chitin. Subsequently, a deep eutectic solvent of betaine and urea (B/U) was used to for protein and chitin isolation.

Results

A maximum of 15% of fat was isolated, with no positive effect from the US or HP treatments. The US treatment enhanced the phenolic extraction yield by 38.69%, while HP negatively affected the antioxidant capacity. B/U was efficient in separating proteins and chitin, resulting in a protein concentrate with a protein content ≥80% and a chitinous fraction with a chitin content ≥70%.

Conclusion

House cricket biomass can be refined into valuable fractions with a quick and simple method, making the process industrially relevant.

An in silico approach to unveil peptides from Acheta domesticus with potential bioactivity against hypertension, diabetes, cardiac and pulmonary fibrosis

Entomophagy is a sustainable alternative source of proteins for human nutrition. Acheta domesticus is one of the three insect species that complies with the European Union Regulation on novel foods, but to date, there are no reports on their potential bioactive peptides. In this study, an in silico approach was applied to simulate the gastrointestinal (GI) digestion of six A. domesticus proteins and identify new peptides with potential anti-hypertensive and/or anti-diabetic properties, resulting from their capability to inhibit the somatic Angiotensin-I converting enzyme (sACE) and/or dipeptidyl peptidase 4 (DPP-4), respectively. A molecular docking protocol was applied to evaluate the binding interactions between the 43 peptides ranked with high probability of being bioactive and three drug targets: DPP-4 and two catalytic domains (N- and C-) of sACE. Five peptides (AVQPCF, CAIAW, IIIGW, DATW and QIVW) showed high docking scores for both enzymes, suggesting their potential to inhibit the DPP-4 and both catalytic domains of sACE, thus possessing multifunctional bioactive properties. Two peptides (PIVCF and DVW) showed higher docking scores for the N-domain of sACE, indicating a potential action as selective inhibitors and consequently with anti-cardiac and pulmonary fibrosis bioactivities. This is the first study identifying peptides originated from the simulated GI digestion of A. domesticus with potential activities against hypertension, diabetes, cardiac and pulmonary fibrosis.

Influence of Dietary Protein Content on the Nutritional Composition of Mealworm Larvae (Tenebrio molitor L.)

The use of insects as livestock feed is becoming increasingly accepted because they provide an important source of protein. The purpose of this study was to investigate the chemical composition of mealworm larvae (Tenebrio molitor L.) reared on a range of diets that differed in nutritional composition. Focus was placed on the influence of dietary protein content on larval protein and amino acid composition. For the experimental diets, wheat bran was chosen as the control substrate. The following types of flour-pea protein, rice protein, sweet lupine, and cassava, as well as potato flakes, were mixed with wheat bran and used as the experimental diets. An analysis of the moisture, protein, and fat content was then carried out for all diets and larvae. Furthermore, the amino acid profile was determined. It was shown that supplementing the feed with pea and rice protein was most suitable in terms of high protein yield in larvae (70.9-74.1% dry weight) with low fat content (20.3-22.8% dry weight). The total amino acid content was highest in larvae that were fed with a mixture of cassava flour and wheat bran (51.7 ± 0.5% dry weight), as well as the highest content of essential amino acids (30.4 ± 0.2% dry weight). Moreover, a weak correlation between larval protein content and diet was identified, yet a stronger influence of dietary fats and carbohydrates on larval composition was found. This research could result in improved formulations of artificial diets for Tenebrio molitor larvae in the future.

Waste Orange Peels as a Feed Additive for the Enhancement of the Nutritional Value of Tenebrio molitor

Lately, additional attention is being placed on edible insects, since they constitute an excellent, cost-efficient source of proteins with a low ecological footprint. Tenebrio molitor was the first insect that was considered edible by EFSA in 2021. This species can replace conventional protein sources and thus, it has the potential to be used in many different food products. In the present study, a food by-product that is commonly produced (i.e., albedo orange peel waste) was used as a feed additive for T. molitor larvae, in an effort to further improve the circular economy and enhance the nutritional value of the insects. To this end, bran, which is commonly used as feed for T. molitor larvae, was fortified with the albedo orange peel waste (up to 25% w/w). Larval performance, in terms of larval survival and growth, as well as the larval nutritional value, i.e., the content of protein, fat, carbohydrates, ash, carotenoids, vitamins A and C, and polyphenols, was evaluated. Based on the results, the increase in the percentage of orange peel albedos in T. molitor feed resulted in a subsequent increase in the content of larvae in carotenoids and vitamin A up to 198%, in vitamin C up to 46%, and an increase in the protein and ash content up to 32% and 26.5%, respectively. Therefore, the use of albedo orange peel waste for feeding of T. molitor larvae is highly recommended, since it results in larvae with enhanced nutritional value and at the same time, the utilization of this feeding substrate further lowers the cost of insect farming.

Influence of Different Diets on Growth and Nutritional Composition of Yellow Mealworm

Insects are a pathway through which agro-food waste can become a high-quality source of nutrients for both livestock and humans. Yellow mealworm (Tenebrio molitor L., Coleoptera: Tenebrionidae) larvae are currently one of the insect species permitted for consumption, and they are reared on a large scale in Europe. This study evaluated the effect of seven diets containing byproducts such as wheat, rye bran, rapeseed meal, rapeseed cake, flax, and milk thistle cakes on the insect’s growth performance, feed conversion ratio (FCR), efficiency of conversion of ingested feed (ECI), nutritional quality of the larvae, and the composition of fats and fatty acids they contained. The lowest FCR based on the fresh and dry basis was 3.32 and 2.01, respectively. The ECI values were statistically different for larvae reared on different experimental diets (mean value 45.7%). As for the nutritional profile, protein and fats ranged from 43.6 to 53.4% d.m. and from 22.3 to 30.0% d.m., respectively. The major fatty acids in all samples were oleic acid (32.97–46.74% of total fatty acids (TFA)), linoleic acid (22.79–38.98% of TFA), and palmitic acid (12.80–17.81% of TFA). This study offers a new opportunity to use and efficiently convert cheap industrial byproducts using yellow mealworms.

Study on the Effect of Hydrothermal Carbonization Parameters on Fuel Properties of Chicken Manure Hydrochar

Economic development and population growth lead to the increased production of chicken manure, which is a problematic organic waste in terms of its amount, environmental threats, and moisture content. In this study, hydrothermal carbonization, an emerging way of waste disposal, was performed on chicken manure to produce an energy-rich material called hydrochar. The effects of hydrothermal carbonization temperature (180, 240, 300 °C) and process time (30, 90, 180 min) were summarized. Proximate and ultimate analysis, as well as low and high heating values were applied both on raw material and derived hydrochars. Additionally, the performance of the process was examined. The obtained results show that hydrothermal carbonization is a feasible method for chicken manure disposal and valorization. Although the process time did not influence the fuel properties of chicken manure considerably, a higher temperature led to a significantly higher heating value, reaching 23,880.67 ± 34.56 J × g^-1 at 300 °C and 180 min with an improvement of ~8329 J × g^-1 compared with raw chicken manure (15,551.67 J × g^-1). Considering the energy gain value, the hydrochar derived at 240 °C in 30 min had the best result. Moreover, the energy consumption for this process was relatively low (124.34 ± 8.29 kJ × g^-1). With its still feasible fuel properties and high heating value of 20,267.00 ± 617.83 kJ × g^-1, it was concluded that these parameters of chicken manure hydrochar are the most beneficial and present a potential alternative for conventional fuel.

Determining the Effect of Different Reproduction Factors on the Yield and Hatching of Tenebrio Molitor Eggs

Simple Summary

This study investigated the effect of various factors on the reproduction of the yellow mealworm Tenebrio molitor. More specifically, the effect of (1) the use of a grid, (2) oviposition duration, (3) age of the beetles and (4) beetle density were examined. For these parameters, it was investigated how they influence the number of eggs laid per beetle as well as the egg hatching rate and time. All these factors had a clear impact on the number of eggs. The results of this study will help producers to optimize their breeding method in order to obtain higher yields.

Abstract

Whereas the production of conventional livestock can rely on years of knowledge and experience, the mealworm production industry is still in its early stages. Although the yellow mealworm Tenebrio molitor has been cultivated as feed for pets and zoo animals for quite some time, the optimization of the reproduction process has not been widely explored. For reproduction, beetles are placed in crates supplemented with a substrate to oviposit their eggs. After a specified time, the beetles are removed, and the eggs are further cultivated to develop into larvae. Factors such as oviposition duration and beetle density influence the number of produced mealworms per beetle, partly due to the cannibalistic behavior of the beetles. However, reproductive success has mostly been assessed by determining the number of offspring several weeks after oviposition. As a result, the number of eggs laid and their hatch rates are unknown. In this research, eggs are separated from the oviposition substrate, i.e., harvested. This approach allows to determine the influence of beetle density, oviposition duration, beetle age and the use of a grid during oviposition on the number of eggs produced and the egg hatching rate and timing thereof. In addition, the influence of the harvesting method on the hatching of T. molitor′s eggs was determined.

A Literature Review of the Use of Weeds and Agricultural and Food Industry By-Products to Feed Farmed Crickets (Insecta; Orthoptera; Gryllidae)

Global socioeconomic systems exacerbate disparities that leave a disturbing proportion of the human population malnourished, making conventional food sources such as animal livestock unsustainable at global scales. Edible insects have the potential to solve both malnourishment and the unsustainability of conventional livestock agriculture. The sustainability and accessibility of farmed, edible insects, however, depends on their feed source. Future expansion of farming rests on developing locally available and affordable insect feeds. This article presents a literature review of studies which evaluate the performance of edible crickets (Orthoptera) in response to alternative feed sources such as weeds and the byproducts of agricultural and food industries. For each insect species evaluated, we analyze measurements of feed and insect performance, feed composition, effects of diet on cricket growth and survivorship, as well as other sources of performance differences. The aim of this review is to assess the current state of alternative feed research for farmed crickets and to provide guidelines for future studies on alternative feeds.