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Abstract

The yellow mealworm, super worm, and house cricket are among the most widely produced insects, with high feed conversion efficiency. However, their nutritional composition and development rate generally vary with environmental conditions. From an economic point of view, rearing conditions such as diet, temperature, and development time; insect performance such as mortality and nutritional value are the most important factors. In order to assess the development, growth, feed conversion efficiency, and chemical composition of Zophobas morio (Coleoptera: Tenebrionidae) larvae fed with diets containing poultry litter, an experiment was conducted. Five diets with varying levels of poultry litter inclusion (0, 25, 50, 75, and 100%) were used to replace the control diet (broiler feed), with five replicates containing 25 larvae per sample unit. Larval growth and development were assessed, and the chemical compositions of both the diet and Z. morio larvae were determined. Significant differences were observed among treatments for development time, survival rate, pupa weight, adult weight of Z. morio subjected to different poultry litter-based diets, as well as in the nutritional index bioassay. The longest development time and the highest larval mortality were observed in the 100% poultry litter-based diets. The highest percentage of crude protein in larval meal (%CP) was obtained with the addition of 25 and 50% poultry litter and was lowest with 100%. The incorporation of poultry litter into the diet of Z. morio has a multifaceted impact on growth and feed conversion efficiency. Elevated levels of poultry litter inclusion led to an extension in development time, yet food conversion efficiency attains optimization with an inclusion rate of up to 50%. Consequently, the decision regarding the proportion of poultry litter in the diet should be carefully weighed, taking into account breeding objectives, efficiency considerations, and cost factors. This ensures the attainment of an optimal balance between larval growth and nutritional efficiency.

In: Journal of Insects as Food and Feed

Abstract

The recycling of minerals is crucial for the future circular agriculture. Black soldier fly larvae (BSFL) can accumulate minerals in their body. This study investigated the effects of adding mineral-enriched BSFL, grown on substrates containing sewage sludge recyclates (SSR), to broiler feed to reintroduce minerals from waste streams currently subject to regulatory restrictions back into the nutrient cycle. Feed, nutrient, mineral and heavy metal intake, growth, blood metabolites and immunoglobulins, bone characteristics and mineral status of broilers were studied in response to different mineral-enriched BSFL supplements. Eighty newly-hatched mixed-sex Ross 308 chicks were divided into four groups, with six replicate pens per group. BSFL used in the broiler experiment were grown either on a modified Gainesville fly diet (FD) (L-FD) or on FD supplemented with 4% of sewage sludge biochar (L-BCH), or on the FD supplemented with Single Superphosphate (SSP) SSR (L-SSP). All broilers were fed age-specific diets and either had no access to BSFL (CON) or received 15% of CON birds’ feed intake as defrosted BSFL from three different sources. Inclusion of 15% of mineral-enriched whole BSFL in broiler rations had no adverse effects on growth performance parameters, nutrient intakes, nutrient conversion efficiency, plasma metabolites and immunoglobulins ( P > 0.05 ). Birds in BSFL supply groups had higher serum Ca concentrations than CON birds ( P < 0.05 ). L-BCH supplied birds had a lower serum P than CON birds ( P < 0.05 ). Tibial characteristics and mineral status of birds were not affected by larvae supply ( P > 0.05 ). Heavy metal intake (manganese, iron, zinc, copper, arsenic, cadmium, lead, and mercury) of the birds was not affected by dietary treatments ( P > 0.05 ). In conclusion, 15% of mineral-enriched-BSFL reared on SSP can be included in broiler diets for 42 experimental days without adverse effects on nutrient intakes, growth performance parameters and bone condition.

In: Journal of Insects as Food and Feed

Abstract

Entomophagy, the practice of consuming insects, has long been recognized as a sustainable and renewable source of food. This study aimed at assessing the nutritional value of three species of wasp larvae (Provespa barthelemyi, Vespa mandarinia, and V. velutina) and explore effective strategies to address enzymatic browning during processing. The study reveals that wasp larvae exhibit considerable potential as a dietary resource, primarily due to their high protein content, more than 50% of the total dry matter. Remarkably, the presence of vitamin B2 in wasp larvae was unexpectedly high, with an average concentration of 2.20 mg/100 g. Additionally, enzymatic browning process in wasp larvae is closely associated with phenol oxidase (PO) activity. The simultaneous treatment of ascorbic acid at a concentration of 0.2% (w/v) and high hydrostatic pressure at 300 MPa significantly inhibited PO activity. Notably, the combined treatment exhibited a certain degree of efficacy in retaining the taste and texture of the larvae. To the best of our knowledge, this study pioneers the novel combined treatment aimed at mitigating browning in wasp larvae. Overall, our research reveals that wasp larvae boast a wealth of nutritional components, rendering them as a new resource food. Our research also provides an innovative approach for wasp processing.

In: Journal of Insects as Food and Feed

Abstract

Insects are garnering attention as promising protein sources for broiler diets, presenting nutritional and environmental benefits comparable to plant-based protein sources. Various insects have been explored as broiler feed ingredients, including mealworm (Tenebrio molitor and Zophobas morio), cricket (Gryllidae), grasshopper (Acrididae), black soldier fly larvae (Hermetia illucens), silkworm pupae (Lepidoptera), bloodworm (Chironomidae), and housefly maggot (Musca domestica Linnaeus). We reviewed the literature involving these insects to assess their impact on broiler diets. Previous research has indicated that supplementing broiler diets with mealworm larvae meal (0.3 to 1.0% inclusion level) improved growth performance. Black soldier fly larvae meal (2.0 to 5.0% inclusion level) can replace protein sources. Similarly, dietary supplementation with silkworm pupae meal (1.5 to 5.0% inclusion level) can also replace protein sources, while including dietary supplementation with housefly maggot meal (1.6 to 4.0% inclusion level) enhanced growth performance in broiler chickens. However, few studies have focused on the effects of dried crickets, dried grasshoppers, and bloodworm supplementation on broiler performance and health. Despite the limitation that insects are more expensive compared to soybean meal or fishmeal, the short breeding period and the high nutritional content of insects make their use in broiler diets generally promising. Our meta-analysis of 28 studies on black soldier fly larvae supplementation found that it significantly decreased average daily feed intake and increased average daily gain with an optimal level of 15.3% determined through quadratic regression analysis. In conclusion, supplementing broiler diets with different insects has potential as a strategy to enhance the growth performance of broiler chickens without compromising overall health.

Open Access
In: Journal of Insects as Food and Feed

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