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Abstract

Unsustainable agriculture contributes to disastrous global effects – insect-based feed shows potential due to their sustainable, nutritional, and waste upcycling properties. Current EU legislation restricts insect-based meals to fish, pork, and poultry feed; but the near-future shows a great potential for wider acceptance in livestock feed. Black soldier fly larvae (BSFL), mealworm (MW), field cricket (FC), and banded cricket (BC) were sourced within three consecutive weeks – each batch was prepared, freeze-dried, then milled, and stored at −20 °C. Chemical composition of whole-insect meals was analysed for ether extract (EE), crude ash, and nitrogenic contents using standard wet chemistry protocols. Monogastric in vitro digestibility was determined through replicating gastric and full intestinal digestion; during this, R-amino acid content was determined through protein hydrolysis kinetics. Additionally, ATR-FTIR was used for molecular analysis, including identification of nutrient-associated functional spectral bands – structural differences were compared through principal component analysis. Insect-based ATR-FTIR analysis demonstrates notable differences in Amide regions, suggesting distinct protein secondary structures, but overall, FC and BC contain the highest crude protein (CP) levels. The lowest CP content was in BSFL; however, BSFL contained the highest ash content – likely consequence of high calcium. Dry matter (DM) yielded lowest in the crickets (FC-28.6; BC-26.9 g/100 g), and highest in MW-38.5 g/100 g; the sum of CP + EE in MW represented >80% DM, but with higher EE contents-CP: EE = 2.45. Data shows greater chitin content in crickets than BSFL + MW. Crickets showed greater neutral detergent fibre (NDF) than BSFL + MW; however, acid-detergent fibre (ADF) was similar among all species, suggesting NDF may include amalgams of interlinked nutrients released by acid digestion. This first study shows for the first time evidence that rearing conditions and substrates influences molecular structure. Exponential solubilisation was observed during pepsin + pancreatin digestion for all, but BSFL exhibited the highest degree-of-hydrolysis during the pancreatin phase, surpassing others. Analysis indicates protein hydrolysis differences are linked to trypsin activity susceptibility.

Open Access
In: Journal of Insects as Food and Feed
Authors: , , and

Abstract

Agricultural by-products can serve as an excellent food source for edible insects, but their high-fibre properties can present challenges. One solution to this is fermentation, which can enhance their nutritional value by breaking down the fibre. However, little research has been conducted on how this method interacts with other environmental factors in insect rearing. To address this gap, our study aimed to investigate the impact of substrate fermentation and larval density on black soldier fly (BSF) larvae. We compared fermented substrates (fermented spent grain and additionally fermented ensiled grass) with standard fibrous substrates (spent grain and ensiled grass) and applied two larval density treatments (high and low). Our findings revealed that prepupal mass was significantly greater in fermented substrates than in standard fibrous substrates, with variations dependent on the substrate and larval density treatments. Larval density significantly influenced prepupal mass only in the fermented spent grain treatment. Substrate type influenced development time, with fermented spent grain resulting in a shorter development time than ensiled grass. However, substrate fermentation and larval density did not affect development time. Substrate fermentation only increased larval survival when individuals were reared on spent grain at high larval density. There were no significant differences in survival between fermented and standard substrates in other substrate and larval density combinations. Our study demonstrates that fermentation could serve as a way to amend fibrous substrates, making them suitable for rearing BSF larvae; however, its effects depend on environmental factors such as larval density.

In: Journal of Insects as Food and Feed
In: Journal of Insects as Food and Feed

Abstract

The absence of habitat-based guidance for wetland managers on the British mosquito assemblages has in recent years prevented development of the ecological aspect of medical entomology in the UK. This has been particularly relevant in the context of emerging mosquito-borne disease and the creation of wetlands for biodiversity and flood-alleviation goals. This study aimed to provide empirically derived habitat-based predictions in order to assess the suitability of English wetland habitats for mosquitoes. Entomological field data on mosquito density and diversity were collected at 12 English wetlands in 2017 and 2018 using immature and adult mosquito surveys. Wetlands were chosen representing a number of wetland categories that included coastal, urban, wet woodland and established freshwater wetlands to identify key species and functional groups to inform predictions of mosquitoes by aquatic habitat type. Nineteen species were recorded from eight functional groups, totalling 38,577 adult female (19 mosquito species groups) and ~2,000 immature mosquitoes in 13 aquatic habitat types. Approximately 90% of all trapped mosquitoes were attributed to one of five species groups. The most common species were: Aedes (Och.) caspius (Pallas, 1771) (~35% of all mosquitoes), associated with coastal estuarine and flooded grassland sites, Ae. cantans/annulipes (19.7%) in wet woodland field sites, Anopheles claviger (16.2%) and Coquillettidia richiardii (12.6%) with the widest occurrence, found in nearly all field sites, and Ae. detritus (6.9%) in brackish field sites. Across the study, adult mosquito activity increased from week 21 with wet woodland Aedes mosquitoes, until week 40 with open-flood water species, with greatest diversity of species during weeks 23–30. The resulting data inform efforts towards developing predictive tools for non-entomologists to accurately predict the presence and abundance of British mosquitoes in a given habitat, using local knowledge of seasonal aquatic habitats.

Open Access
In: Journal of the European Mosquito Control Association

Abstract

Reared insects such as black soldier fly larvae (Hermetia illucens) are considered a potential alternative feed protein. However, dietary exposure to insecticide residues via the substrate could adversely affect performance indicators (yield/survival) and substance-transfer from substrate to larval biomass could result in non-compliance with low legal limits. Effects of pyrethroid insecticides cypermethrin and deltamethrin were tested at varying concentrations, with or without the synergist piperonyl butoxide (PBO). Concentration/response curves for yield were estimated and samples were analysed to determine concentrations of parent compounds and selected metabolites. Results suggest that deltamethrin is highly toxic to H. illucens larvae: the critical effect dose for 10% yield loss was estimated to be 0.04 mg/kg, compared to a legal limit in wheat of 2.0 mg/kg. Cypermethrin was comparatively less toxic, in line with prior studies, but may also cause significant adverse effects even for exposure levels below the legal limit – especially when combined with PBO. For both substances, transfer from substrate to larvae is a potential issue due to low limits, and transfer as well as toxicity are increased by presence of PBO. Some metabolites could be detected, but more research is needed to determine resistance mechanisms involved.

Open Access
In: Journal of Insects as Food and Feed

Abstract

This study explores using insects as a high-quality protein source rich in bioactive peptides for human nutrition. The objectives include establishing optimal conditions for peptide extraction, identifying their sequences, and assessing their potential as antioxidants and antimicrobial agents in Arsenura armida flour. The protein content in the A. armida flour extract was 54%. To obtain potential antioxidant and antimicrobial peptides, a 10:1 and 1:1 enzyme (pepsin)/substrate ratio was employed, with digestion times of 2 h (A2) and 1 h (A4), respectively. The IC50 value for the antioxidant assay DPPH (2,2-Difenil-1-Picrilhidrazilo) was 22.5 μg/μL for A2. In the antioxidant in vivo assay with Caenorhabditis elegans, A2 peptides at concentrations of 0.75 μg/μL and 1.5 μg/μL exhibited a survival percentage ranging from 32.6% to 35.3%. The A4 sample demonstrated the highest antimicrobial activity, inhibiting the growth of Gram-positive bacteria (Listeria monocytogenes and Staphylococcus aureus) with MIC (minimum inhibitory concentration) values of 0.11 μg/mL and 0.23 μg/mL and MBC (minimum bactericidal concentration) of 0.23 μg/mL for both. Peptide analysis revealed that A2 contained peptides with identified antihypertensive (37%) and antioxidant (58%) activities, while A4 comprised peptides with antihypertensive (62%), antioxidant (31%), and antimicrobial (2%) properties. The antimicrobial peptides identified through the BIOPEP database were LFGF and FLLF. This investigation underscores the potential of A. armida peptides as valuable components in functional foods or nutraceuticals, offering health benefits beyond basic nutrition.

In: Journal of Insects as Food and Feed

Abstract

We report occurrence data of mosquitoes in Scotland which were routinely collated by the British Mosquito Group for the period 1886 to 1993 (232 records), and by the Mosquito Recording Scheme since 2005 (11 records). We also report a set of new field data mainly based on mosquito immature sampling in aquatic habitats during the summers 1998 and 2012, in both Scotland (20 data) and England (11 data). The occurrences in Scotland (263 data in total) include a total mosquito fauna of 18 species. They include, for the British Isles, the northernmost record of Anopheles claviger sensu stricto, collected on Orkney, and the northernmost record of Culex pipiens, collected on Shetland, both in 2012. The latter is the northernmost mosquito record of Great Britain to date.

Open Access
In: Journal of the European Mosquito Control Association

Abstract

One-fifth of the edible insect species identified worldwide have been documented in Mexico. In states with an entomophagy tradition, insects have been incorporated into the local cuisine. Results show that the country has a wide diversity of climates and vegetation; thus, each state has its own set of edible insects. This narrative review aims to determine the current state of entomophagy in Mexico, divided into two segments: wild-collected insects, and farmed insect products, and to identify the current trends, both in research and in commercial products available. Wild-gathered insects are mostly purchased at local marketplaces, with prices varying widely, depending on the insect and the sales point. Increased demand for wild edible insects, and the loss of natural habitat, have put some insect species at risk of extinction. Since whole edible insects are wild-gathered and commercialised whole in traditional markets, there are currently no specific mandatory standards for food products containing insects as ingredients. Alongside traditional wild insect activities, there is a fledgling industry of farmed edible insect products which can be purchased online. In conclusion, while the wild-gathered edible insect market is well established, a farmed insect products market is developing, with manufacturers incorporating insect flour into food products where the insect element is inconspicuous, seeking to appeal to a wider range of consumers, yet most recent academic research focuses on wild edible insect species, with a near absence of research articles on the farmed insect species. The insect food product industry would benefit from a closer collaboration with the academic research sector. Furthermore, the lack of a specific regulation for manufacturing insect food products constitutes a disadvantage for firms seeking to export to countries with stricter regulations. Also, with the food safety concerns inherent in wild-gathered insect consumption, studies focusing on the sanitary aspects of entomophagy are insufficient.

In: Journal of Insects as Food and Feed

Abstract

The distribution of mulberry leaf nutrients and trace elements into silkworm larvae over its development into pupa was investigated for potential novel food applications. Four stages of chronologically collected silkworm larvae, fed with mulberry leaves, were sampled. Proximate composition, vitamin A, β-carotene, mineral, fatty, and amino acid profiles were analyzed. The highest protein content was 63.68% in the fourth instar, whereas lipid was markedly highest at 31.85% in pupa. Magnesium and potassium were found to exceed the Thai recommended daily intake standard (RDI) in almost all stages, except for the potassium in the pupa. Vitamin A in the third to fifth instar was also found to be more than Thai RDI. The distinct highest zinc and fatty acid content were detected in the pupa. Monounsaturated fatty acids were detected at the highest levels in all stages. Sulfur-containing amino acids were abundant in the fifth instar. The fourth instar, the fifth instar, and the pupa are recommended as sources of protein, amino acids, fatty acids, and lipids in developing suitable food products.

In: Journal of Insects as Food and Feed

Abstract

Black soldier fly larvae (BSFL, Hermetia illucens) are an alternative source of protein whereas little research has yet been conducted to investigate the potential application of feed substrate waste (FSW) from larval production in aquaculture. The nutritive value and physicochemical properties of FSW from BSFL were here investigated in vitro. Ten-day-old first-instar larvae were cultivated on two feed substrates: laying hen feed (FS I) or a laying hen feed-rice bran blend (1:1 w/w, FS II). FSW samples were collected at day 4.5 (0.5FSW) and day 9 (1FSW) of larval rearing, and compared to the original feed substrate (0FSW). Crude protein increased depending on FS type, harvesting time (HT), and their interaction. Crude lipid, crude fiber, acid detergent fiber, neutral detergent fiber, crude ash, nitrogen-free extract, and gross energy decreased ( P < 0.05 ). Analysis of the physicochemical properties of FSW by various techniques (scanning electron microscopy, differential scanning colorimetry, X-ray diffractometry, and Fourier transform infrared spectroscopy) revealed qualitative and quantitative changes in FSW, driven by biological processes of BSFL. The digestibility of protein in FSW was determined by an in vitro protein digestibility (IVPD) test using crude digestive enzyme extracts from Nile tilapia (Oreochromis niloticus) and striped catfish (Pangasianodon hypophthalmus). 1FSW from FS I showed significantly better availability of protein relative to 0.5FSW ( P < 0.05 ), while the IVPD of FSW from FS II was stable ( P > 0.05 ) or reduced ( P < 0.05 ). Findings from this study suggest FSW from BSFL cultivation could be a protein source in aquafeed.

In: Journal of Insects as Food and Feed