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Abstract
Edible insects such as lesser mealworm (Alphitobius diaperinus) are a promising new protein source for food and feed. The feed substrate on which these insects are reared may be contaminated with residues of insecticides originating from agricultural products that may impact insect performance. In this study, two generations of A. diaperinus were chronically exposed to spinosad (2.0 and 0.2 mg/kg) and imidacloprid (0.1 and 0.01 mg/kg) in the substrate. The aim was to determine sublethal effects on performance measures (total biomass (yield), mean individual weight, number of alive individuals) of larvae, pupae, and adult beetles, as well as pupation and eclosion. Exposure to spinosad at 2.0 mg/kg resulted in significant adverse effects on most performance measures of larvae, of both generations. Imidacloprid caused a reduction in yield and mean individual weight of the larvae as compared to the control at 0.1 mg/kg, while an increase in those measures was observed at 0.01 mg/kg. Significant adverse effects on adult beetles were only observed for imidacloprid at 0.1 mg/kg, and no significant effects of this insecticide on pupation and eclosion were observed. The concentrations of tested substances in larval samples were negligible for both generations, however, transfer from substrate to larval biomass was higher in the offspring generation relative to the parent generation. More research is needed to fully assess the hazard of insecticide residues to cause sublethal effects on A. diaperinus, for which method development for more cost-efficient designs is required.
Abstract
Crickets are being reevaluated as food and livestock feed due to their high nutritional value and low environmental impact during production, as food waste can be used as feed. On the other hand, current cricket production uses feed used in aquaculture and poultry farming, and these feeds contain animal proteins such as fish meal and chicken meal. This is simply converting other animal proteins into insect proteins. Therefore, this study aimed to test whether two-spotted cricket powder can be used as a substitute for fishmeal in diets for Gryllus bimaculatus production. Cricket weight, feed efficiency, and number of crickets were evaluated by feeding rice bran: cricket powder = 85:15 and rice bran: fish meal = 85:15, respectively, referring to the feed mix ratio used by cricket producers. Results showed no statistically significant differences between the two experiments in cricket weight and feed conversion ratio. When data were obtained separately for each growth phase, cricket weight was found to be highest in the fourth post-hatching week for the diet with cricket powder and then decreased (initial input: 1 g; 28 days: 89.45 ± 22.19 g; 35 days: 49.47 ± 14.11 g). Feed conversion efficiency was found to be higher in the second half of growth (1-7 days: 0.48; 23-28 days: 0.80). The use of insect powder as bait for crickets is a new proposal. In cricket production, adults with low reproductive capacity are packaged and sold as food or livestock feed, but by using insect powder as feed during cricket production, it is possible to reduce animal protein in the feed. In the future, we plan to investigate the usefulness of mass-produced insect powder as feed for crickets.
Abstract
Insect value chains are a complex system with non-linear links between many economic, environmental, and social variables. Multi-objective optimization (MOO) algorithms for finding optimal options for complex system functioning can provide a valuable insight in the development of sustainable insect chains. This review proposes a framework for MOO application that is based on gradual implementation, beginning with factors that have an immediate impact on insect production (feed qualities, resource utilization, yield), and progressing to integrated units (environmental, social, and economic impacts). The review introduces the key hotspots of insect production chains, which have been developed in suitable MOO objectives. They represent aspects of resource use, feed quality and its conversion by insects, labor safety and wage fairness, as well as environmental impacts. The capacity of the suggested MOO framework to describe all facets of sustainability may have certain limits. To determine the framework’s applicability and the specific MOO algorithms that can perform the function, modeling and further testing on real insect production chains would be necessary for the intended objectives.
Abstract
Sustainable food system innovations are urgently needed to feed a growing human population while staying within planetary boundaries. Farmed edible insects have received considerable scientific and public attention due to their potential to improve food system circularity by upcycling nutrients from organic residual streams to nutritious food. Earthworms, as non-insect invertebrates, have remained largely unrecognized in the future foods debate. However, they are already widely farmed at industrial scale for their capacity to recycle organic wastes and improve soil fertility. We conducted a systematic literature review to provide a quantitative basis on earthworm nutritional composition, thereby positioning earthworms in the future foods debate. Here we show, based on evidence from 142 scientific studies, that farmed earthworms are a potentially interesting food source. They have an attractive nutrient composition compared to the main farmed edible insect species, being especially rich in protein, low in fat and containing a favourable profile of essential amino acids. The content of important fatty acids, minerals and vitamins in earthworm biomass is higher or lower than in edible insects, depending on the feed material. Crude protein and fat contents are higher in farmed versus wild earthworms, indicating that farming conditions provide a lever for further improving the nutritional composition of earthworm biomass. Whether earthworm species or feed materials affect earthworm nutritional composition could not be finally clarified based on the available data. We conclude that earthworms have high potential as a future food from a nutritional perspective, mainly as an alternative source of protein. The integration of earthworm farming in future food systems can be expected to improve sustainability and circularity, potentially giving earthworms an advantage over edible insects.
Abstract
Sericulture is a common practice around the globe. The silk produced by moths is widely known, but the nutritional potential of silkworms for human consumption is not well recognized. The present study analyses the nutritional contents and antioxidant properties of the prepupae and pupae stages of Samia ricini. Proximate analysis was carried out following AOAC methods. The antioxidant activity was studied by Ferric reducing antioxidant power assay, 1,1-Diphenyl-2-picryl-hydrazyl, and 2,2’-Azinobis-(3-ethylbenzothiazoline-6-sulfonate) assays. The study observed substantial quantity of nutritional content in both the prepupae and pupae stages of S. ricini. The moisture content was found to be 70-72% in wet tissue weight. Protein content was 13-15% and 46-51% in wet and dry tissue, respectively. The study observed significant increase in protein content from prepupae to pupae stages. Fats and carbohydrate content also showed significant differences between the two stages of S. ricini. The pupae showed more potent antioxidant activity compared to prepupae. The IC50 values for pupae were 3.29 ± 0.12 mg/mL and 1.79 ± 0.32 mg/mL for DPPH and ABTS assay. In contrast, prepupae stage showed weaker antioxidant properties with IC50 values of 7.26 ± 0.52 mg/mL and 3.11 ± 0.12 mg/mL. The present study suggests that the pupae of S. ricini could be an alternative source of proteins, antioxidants, and beneficial food to incorporate into daily diet compared to the prepupae stage.
Abstract
The desert locust (Schistocerca gregaria) is a notorious swarm-forming agricultural pest widely collected for its use as food and feed. Its ability to grow on tomato leaf waste as a sole nutritional source was investigated given its ability to consume a wide range of plants. The growth and nutrient composition of desert locusts and their generated frass were compared in nymphs reared on tomato leaves versus wheatgrass. The desert locusts demonstrated higher growth on wheatgrass diet, but they also thrived on tomato leaves without observed mortalities. An average production of 14.38 g desert locust biomass consumed 375.8 g of fresh tomato leaves. Desert locusts fed with tomato leaves had higher crude protein content (61% compared to 58% in wheatgrass-fed desert locusts) and lower fat content (8% compared to 14% in wheatgrass-fed desert locusts). The diet also influenced the levels of Ca, Cu, Mn, S, and Zn in the desert locust biomass. Furthermore, the analysis of the generated frass revealed significant differences in the levels of B, Ca, Cu, K, Mg, Mo, Na, P, S, Zn, and N, depending on the plant material provided. The findings suggest that the desert locust can be reared efficiently on tomato leaves, transforming this waste stream into a protein-rich insect biomass and frass.
Abstract
The yellow mealworm (Tenebrio molitor) is a promising insect species for mass-rearing for the production of feed and food. In mass-production systems, insects may be exposed to abiotic stressors such as heat stress as well as potentially lethal pathogens. To ensure mass-reared T. molitor populations are healthy and productive there is a need to understand both the risks, and potential benefits of heat stress, on the fitness of insects and their susceptibility to pathogens. In this study, we investigated the effects of a short (2 h) or a long (14 h) heat stress (38 °C) exposure on the susceptibility and the immune responses of T. molitor larvae exposed to a fungal pathogen (Metarhizium brunneum). Larvae were exposed to the pathogen either immediately or five days after the heat stress treatments. The development of heat stressed larvae and their offspring was also assessed. A short heat stress immediately before exposure to M. brunneum increased the survival probability of T. molitor larvae, which correlated with increased antibacterial activity in the hemolymph. The exposure of larvae to short, or long heat stresses five days before pathogen exposure did not affect their survival, despite a temporary lowered body mass gain of heat stressed larvae. However, heat stressed larvae showed decreased hemocyte concentrations when exposed to M. brunneum. We also found an increased body weight in larval offspring of females that had been exposed to a short heat stress as larvae themselves. These findings demonstrate the importance of understanding the effects of heat stress in the long-term. The beneficial effects of heat stress on pathogen susceptibility in T. molitor and the negative effects on body mass gain are only transient, whereas negative effects on immune response (hemocyte concentrations) persist over an extended period.
Abstract
Fats make up a large fraction of the larval biomass in insects and are of increasing relevance for industrial purposes. The quantity of fats accumulated during the larval period can vary greatly among individuals. To selectively breed favourable fat accumulation phenotypes for commercial purpose, a genetic component underlying these differences would be required. In this study we determined the heritability of larval fat accumulation in the common housefly (Musca domestica L.). A nested paternal half-sib breeding design resulted in a total of 47 full-sib families, which produced in total 633 larvae, each phenotyped for their dry weight and fat content (absolute and relative). Adult selection was strictly standardized to reduce the variation in fat content induced by differences in development time during the immature stages: sires and dams were separated according to their pupation day and emergence day, and subsequently pooled into randomized groups. Two animal models were built to estimate the heritability of larval fat accumulation: (1) a Markov Chain Monte Carlo linear mixed model (MCMCglmm) where three sets of priors were used, and (2) one based on linear mixed model using restricted maximum likelihood (ASReml). The results showed a moderate heritability for larval absolute fat content for both MCMCglmm (between 0.30 and 0.38, depending on the set of prior used) and ASReml (0.37 ± 0.11). Slightly higher estimates were obtained for the relative fat content with both the MCMCglmm (between 0.34-0.48) and ASReml (0.47 ± 0.10). In contrast, heritability estimates for larval dry weight were low and could be obtained only with the MCMCglmm model (between 0.11-0.22). This work provides valuable insights into the quantitative genetics of larval fat characteristics, a trait of high relevance for the emerging sector producing insects for feed and food.
Abstract
The commercial accessibility of insect biomass for food and feed necessitates a systematic examination of the various factors that can potentially hinder the efficiency of insect farming. This study focuses on identifying the optimal thermal requirements for the lesser mealworm, Alphitobius diaperinus (Panzer), an edible insect species of particular interest due to its significant potential as a food and feed source. Adults of the species were left to oviposit continuously for 45 days, under controlled laboratory conditions at 20, 25, 30 and 32 °C. The number of eggs laid by the adults, as well as the larval emergence was recorded during this period. Based on the findings, the reproduction output, expressed as the cumulative number of eggs per adult and the cumulative larval hatching rate, was affected by the temperature levels tested here. It has been determined that the optimal reproductive output of A. diaperinus can be attained by maintaining newly emerged adults within a temperature range of 25 to 30 °C for a period of 42 days. During this period, it is anticipated that each adult will yield an average of 73 eggs, while an estimated hatchability rate of 69 and 58% at 25 and 30 °C, respectively. Our study is one of the few that evaluate the efficacy of retaining parental adults of A. diaperinus for oviposition under commercial mass-rearing conditions, taking into account egg and larval production.
Abstract
Edible insects are an emerging approach to provide sustainable proteins in feed. Black soldier fly larvae (BSFL) can also bioaccumulate micronutrients from various substrates. The purpose of this study was to assess whether BSFL can bioaccumulate significant concentrations of bioavailable α and ɣ-tocopherol (TOC) from vitamin E (VE) rich substrates. BSFL were reared on VE rich substrates, e.g. wheat germ oil, bran, etc. α and γ-tocopherol were quantified in larvae and substrates by HPLC. VE bioaccessibility was estimated using an in vitro model of digestion. Uptake efficiency of micellarized VE by intestinal cell was estimated using Caco-2 cells. BSFL were at least as rich in α-TOC, but not ɣ-TOC, as their rearing substrates. VE bioaccessibility was almost always significantly lower in BSFL than in corresponding substrates. Conversely, VE uptake efficiency was either not significantly different or significantly higher in BSFLs than in substrates. Thus, VE enrichment of BSFL from VE rich substrates, in particular co-products such as brans and oil cakes, could be an innovative way to recycle VE and to provide significant amounts of sustainable VE in farm animal feed.