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Abstract
Larvae of the black soldier fly (Hermetia illucens, BSFL) are rich in valuable nutrients and offer a promising alternative protein source for animal feeds. Nonetheless, there is a pressing need to improve both the productivity and quality of BSFL to ensure the viability of BSFL products and facilitating the industrial production. To fulfil the needs of different animals, it is necessary to adjust the profile of essential amino acids (EAAs) in BSFL. Insects excrete surplus nutrients to maintain homeostasis; AAs are excreted by nutrient AA transporters (NATs) in the Malpighian tubules. We aimed to modify the composition of essential AAs by silencing the NAT in Malpighian tubules of BSFL (HiNATt). Silencing HiNATt resulted in a 77.3% increase in the total AA content while 56.2% decrease in body weight. Notably, the contents of some valuable essential AAs were strongly increased (histidine, 256.8%; valine, 198.1% in total compared to the intact larva). These results suggest that inhibiting the HiNATt function could modify the amount of accumulated EAAs. This finding opens a new avenue for producing BSFL with increased nutritional value as an alternative protein source.
Abstract
Interest in the nutrition of the yellow mealworm (Tenebrio molitor L.) larvae is on the rise, leading to an increase in publications on this topic. The absence of a standard protocol and resulting differences in experimental designs reduces comparability among studies and impedes research on mealworm nutrition. To address this, a consensus standardised protocol was developed specifically for the evaluation of mealworm larval growth and performance in feeding trials. The efficacy of this protocol was evaluated through an international ring test involving seven partners using two wheat brans as dry feed (a standard bran and a local bran) at 27 °C and 60% relative humidity. As experimental units, plastic crates filled with 2.1 kg of bran and 10,000 4-week-old larvae were used with six replicates. Agar gel was provided as wet feed ad libitum. The mean individual larval weight and the number of larvae per crate were determined weekly until either three or more replicates ran out of feed or pupation exceeded 10%. At harvest, the total larval fresh biomass and amount of frass was determined. Larval samples were taken for chemical analysis. To assess the protocol, the within (repeatability) and between (reproducibility) laboratory variability was calculated for each parameter. The repeatability was good (limit at 12% (standard) and 14% (local)). The reproducibility was poorer with a limit 2.7 times higher for the standard feed (36%) and 3.8 times higher for the local feed (55%). For both feeds, the total larval fresh harvest, amount of frass and the larval protein concentration were the most consistent both within and among laboratories. The highest variability was observed at the early life stages and for the larvae ash content. The detailed consensus standard protocol and repeatability/reproducibility estimates can be used as basis for future mealworm feeding trials, comparing results and future improvements.
Abstract
As recently shown, black soldier fly larvae (BSFL) are capable of bioaccumulating high concentrations of vitamin E and carotenoids, but the potential bioaccumulation of polyphenols remains unknown. Wheat bran (WB), a common breeding substrate for BSFL, is particularly rich in ferulic acid (FA) and also contains caffeic acid (CA). Numerous studies suggest that these polyphenols have beneficial effects on human and animal health. BSFL ability to bioaccumulate these bioactive compounds was assessed by comparing their concentration in WB and BSFL raised on WB. The three forms of FA and CA, i.e. free, soluble-bound and insoluble-bound, were extracted from WB and BSFL and quantified by HPLC-UV. No form of CA was detected in BSFL. The three forms of FA were detected but the total FA concentration in BSFL (17 ± 1 mg/kg fresh weight) represented only 2% of the total FA concentration measured in WB (810 ± 38 mg/kg fresh weight). Since the larvae were not fasted, another experiment was carried out to find out if the small amount of FA found in the larvae was the FA contained in WB present in their digestive tract. The digestive tracts of fasted and non-fasted larvae at the end of the rearing period were weighted. And it was calculated that all the FA measured in the larvae could be the FA present in their digestive tract. Moreover, the distribution of the three different forms of FA differed between WB and BSFL. Therefore, we have demonstrated that not only BSFL do not significantly bioaccumulate FA from WB but that they apparently metabolize it. Regarding CA as a precursor of FA, the same phenomenon might have happened. However, assuming an equivalent bioaccumulation factor as FA, the amounts of CA theoretically transferred in larvae were too low to be detected.
Abstract
The world’s socio-economic development is continuously increasing the demand for efficient production of food, feed, and energy from the agricultural sector. In this respect, the emerging production of black soldier fly larvae (BSFL) represents a promising system to upscale low-quality resources to higher-quality resources usable as feed or biodiesel. To optimize BSFL production it is critical to establish methods that are relevant to examine how rearing conditions, including temperature, affect growth, metabolism, and body composition at large scale. In a first set of experiments, we therefore compared how small-scale laboratory respirometry chambers (600 larvae) support gas exchange, growth, and metabolism in BSFL with similar measurements obtained from large-scale commercial conditions (>12 million larvae) at ∼34-35 °C. Having observed that small- and large-scale systems generated comparable measurements of growth and metabolism, we used our small-scale respirometry system to examine in detail how substrate rearing temperature ranging from 27.0 to 41.9 °C influenced growth, metabolism, and body composition in BSFL. Here we found that 7-day growth of BSFL was stable and high at 27, 35, and 39 °C, while a rearing temperature of ∼42 °C caused a severe, but sublethal, depression of growth and metabolism. Despite the general similarities in total growth at 27, 35, and 39 °C, we found considerable acceleration of metabolism and development at the two higher rearing temperatures (35 and 39 °C). In contrast, the lower rearing temperature (27 °C) resulted in reduced CO2 production per kg larvae produced and the was associated with a higher crude protein to crude lipid ratio in larvae after the 7-day growth period. Based on these findings we discuss how continued monitoring of gas exchange in production systems holds a potential to optimize production in the emerging industry of large-scale commercial insect production.
Abstract
The European Commission recently authorised the inclusion of insect meal in poultry feed. Black soldier fly larvae meal (BSF) has comparable nutritional value to soybean meal (SBM) and higher calcium content, making it an attractive alternative protein source for laying hens While a few studies have explored this objective, inconsistent results have been reported, likely due to variations in hen age, breed, husbandry systems, and sunflower meal composition across studies, making it difficult to draw clear conclusions. We hypothesised that partial or complete replacement of SBM with BSF has no adverse effects on egg production and quality in laying hens at the initiation of laying (22-30 weeks of age). This study consisted of three dietary treatments and nine replicates per treatment. Diets were a control diet, and two diets containing 5% (BSF5%) and 10% (BSF10%). The experimental unit was a pen (100 × 200 × 200 cm) of 14 Brown Nick laying hens resembling an aviary setting. We found that complete replacement of SBM with BSF10% in the diet of laying hens improved feed efficiency attributed to a lower feed intake in comparison to laying hens fed the BSF5% or the control diets, while production performance, body weight, and egg quality were maintained and the colour of the egg yolk increased. Therefore, replacing SBM with up to 10% BSF in brown laying hens in aviary pens at the initiation of laying had no adverse effects on production performance, chemical and physical characteristics, and sensory attributes of eggs. Maintaining production and egg quality with a lower intake of nutrients requires further investigation.
Abstract
The demand for alternative fishmeal has increased significantly in recent years due to the expansion of the fishing industry. Therefore, insect proteins are becoming more popular as an alternative low-cost bio-source for fish than plant-based fish feeds. In the present study, a dietary mixture of insect protein powder derived from four Indian grasshopper species, namely Oxya hyla hyla, Atractomorpha crenulata, Oxya japonica japonica, and Phlaeoba infumata (insect meal, IM) was substituted for conventionally used fishmeal (FM) in the diet formulation for growing Mozambique tilapia, Oreochromis mossambicus (Peters, 1852) fingerlings. Three formulated diets with IM were prepared, with FM substituted at the rates of 25%, 50%, and 75%, respectively, with a control diet with no IM but only 20% FM. All dietary treatments were administered to tilapia fingerlings for 60 days under laboratory conditions. IM-incorporated diets outperform FM-incorporated diets in growth and digestibility due to their higher food conversion ratio for IM. In terms of growth and survivability in tilapia fingerlings, a 75% replacement of FM with IM demonstrated the most significant efficacy. According to the findings, mixed insect powder derived from four grasshopper species can be used as a partial replacement for FM in formulating the compound fish diet for tilapia fingerlings.
Abstract
This study aims to investigate the structure and diversity of the intestinal microbiome of Gryllus bimaculatus from wild and farmed environments. Additionally, we sought to identify the core microbes to get information on the microbial diversity of the gut microbiome to the farm condition. We analyzed the microbial community diversity in intestinal samples of both wild and farmed G. bimaculatus using high-throughput sequencing of 16S rRNA gene and ITS rRNA amplicons. Using the PICRUSt2 software, we predicted the functional capabilities of bacterial communities. The analysis indicated significant differences in the diversity of the microbial communities (bacteria) within the gut of crickets under farmed and wild conditions, with notably higher bacterial diversity observed in the gut of farmed crickets compared to those in the wild. The gut bacterial communities exhibited significant similarity across the two conditions, and the variations in diversity are primarily influenced by species with low abundance. Genus-level analysis revealed that the abundance of pathogens, including genera Listeria, Staphylococcus, and Candida, was significantly higher in the gut microbiota of farmed crickets than in the wild ones. By identifying core genera (present in over 80% of the samples), we discovered 19 bacterial genera and 1 fungal genus. The core bacterial genera constituted 60.35% and 87.10% of the cricket’s gut bacterial abundance in farmed and wild environments, respectively. The functional prediction analysis performed using PICRUSt2 identified a significant increase of pathways about “Terpenoids and polyketides metabolism”, and “Infectious disease: bacterial” in the farmed group; as well as a significant decrease in pathways about “Environmental adaptation”, “Development and regeneration”, and the “Nervous system”, compared to the wild group. In conclusion our results showed that the gut microbial community of the G. bimaculatus could be influenced by its environment and diet. However, this influence is primarily manifested in the variation of low-abundance genera, with the gut microbial community remains dominated by a few microbial groups. Therefore, it is speculated that the combination of core and edge species in the gut microbial community of the G. bimaculatus may constitute an effective strategy that not only maintains the core functions of the community but also adapts to environmental changes through the diversity of edge species. The high population density and excessive feeding in the farmed condition could have allowed for the creation of a more diverse gut microbiota for G. bimaculatus, including potential pathogens. Therefore, when breeding G. bimaculatus, the environmental hygiene management should be strengthened to reduce the carrying and transmission of pathogens.
Abstract
Meeting global targets for healthier and more sustainable diets calls for a substantial reduction of meat consumption in Western nations, especially red and processed meat. This requires a transition to the large-scale production, marketing, and adoption of alternative proteins. The current state of development of new plant- and insect-based foods holds good promise, but optimizing their sensory quality to the point where they can satisfactorily replace everyday meat-eating experiences remains a challenge, demanding a more consumer-oriented approach. This study investigated how Portuguese adults (