Mealworm Larvae Research Articles

Nutrient Composition and Growth of Yellow Mealworm (Tenebrio molitor) at Different Ages and Stages of the Life Cycle

The nutrient composition of yellow mealworm (YM) Tenebrio molitor varies based on the stages of the life cycle, the rearing conditions, and the feeding substrate. This study monitored the growth of yellow mealworm larvae at 8, 10, and 12 weeks of age, separating samples into large-sized and small-sized insects. During the experiment, we measured the nutrient composition: dry matter (DM), crude protein (CP), crude fat (CF), crude fibre, chitin, crude ash, and nitrogen free extract (NFE) of YM at different age groups and sizes. We measured the nutrient composition of the pre-moult, moult, cuticle, and pupae as well. The results show that there is no significant difference between the compositions of the different age groups, but larger-sized individuals had a higher DM and crude fibre and lower chitin and NFE than the smaller sizes. The pre-moult and moult stages showed no significant difference in nutrient composition. Although the cuticle had a high DM (97.5%), that did not cause any significant difference between the DM of the moult and pre-moult, because it is only a negligible part of the total wet weight. With the increased DM, the crude protein content and the chitin content, fibre, ash content, and NFE increased, while the fat content decreased. The DM, CF, and chitin contents of pupae are significantly lower than those of the pre-moult and moult stages. Our results show that it is the size and not the age that has a positive effect on the nutrient composition of YM.

Staphylococcus aureus artificially inoculated in mealworm larvae rearing chain for human consumption: Long-term investigation into survival and toxin production

The present research reports the results of a long-term study (70 days) of the dynamics of Staphylococcus aureus artificially inoculated in a Tenebrio molitor rearing chain for human consumption. To this end, a rearing substrate consisting of organic wheat middlings was spiked with S. aureus to obtain three initial contamination levels, namely 1 (low level), 5 (medium level) and 7 (high level) Log colony forming unit per gram. Microbial viable counting coupled with metataxonomic analysis were performed to evaluate: i) the persistence and growth of S. aureus in the rearing substrate; ii) the colonization and growth of S. aureus in the insect larvae; iii) the occurrence and load of S. aureus in the frass (excrement from larvae mixed with substrate residues); iv) the presence of S. aureus enterotoxins in the rearing substrate, frass, and larvae. The results of the present study highlighted that wheat middlings contaminated with S. aureus do not represent a suitable environment for the multiplication of the pathogen, irrespective of the initial contamination level. Of note, frass originated from the larvae reared on contaminated wheat middlings might potentially represent a source of S. aureus, with cell loads depending on the initial contamination level. A complex resident microbiota was revealed by metataxonomic analysis. Interestingly, co-occurrence/co-exclusions analysis did not reveal associations between the target microorganism and the microbiota of wheat middlings, larvae, or frass. Considering safety aspects of larvae, the results overall collected suggested that, under the applied conditions, T. molitor represents an inhospitable or even hostile environment for S. aureus, with this latter showing counts below the detection limit in the larvae at the end of the 70-day rearing trial, irrespective of the initial contamination level. The results also suggested that a combination of bactericidal factors, including unfavorable environmental conditions (such as low aw of wheat middlings and frass), might have established in the rearing chain. Finally, the absence of staphylococcal toxins suggests that, even when S. aureus is present at high contamination levels, it is not able to produce toxins in wheat middlings, larvae, or frass.

Feeding the Laying Quails with Mealworm Larvae Meal and Alterations in Egg Quality and Yolk Fatty Acid Profile

The purpose of this study was to investigate the effects of different levels of mealworm (Tenebrio Molitor) larvae meal in Japanese quail (Coturnix coturnix japonica) diets on performance, egg quality, yolk color, and yolk fatty acid composition. A total of forty-eight, 14 weeks-old laying quails were used with 4 replicates in control (basal diet), mealworm larvae meal (MLM) 2% or 4 % treatment groups. Results showed that independently of inclusion level dietary MLM did not affect performance and egg quality parameters. However, color values (L*, a*, b*) of egg yolk changed with the inclusion of both levels of MLM to diet (p<0.5). Outcomes also displayed dietary MLM altered the fatty acid composition of egg yolk dependably the additional level (p<0.5). Diets containing 2 and 4 % MLM did not affect total saturated fatty acid (ƩSFA) content, however, increased total monounsaturated fatty acids (ƩMUFA) (p<0.5). Both supplemental levels of dietary MLM decreased significantly the total polyunsaturated fatty acids (ƩPUFA) of the yolk compared to the control group (p<0.5). According to outcomes of this study, MLM may use in safe as feed material instead of soybean meal at levels of 2 or 4 % without effect on performance parameters in laying quail diets.

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.

The effect of dechitinization on iron absorption from mealworm larvae (Tenebrio molitor) flour added to maize meals: stable-isotope studies in young females with low iron stores

Edible insects have a low ecological footprint and could serve as an alternative dietary iron source. However, chitin, a major component of insects, avidly binds iron and might inhibit iron absorption. We aimed to measure fractional iron absorption (FIA) from Tenebrio molitor-based test meals with and without dechitinization, and to assess the effect of native and low chitin T. molitor on FIA from iron-fortified maize porridge. We measured iron absorption in young females with low iron stores (n=21) from 1) labeled (54FeSO4) fortified maize porridge (maize alone); 2) intrinsically labeled (57Fe added during rearing) T. molitor larvae with native chitin content (NC) added to maize alone; and 3) dechitinized intrinsically labeled (57Fe) T. molitor larvae with low chitin content (LC) added to maize alone. We determined FIA using erythrocyte isotope incorporation and measured in vitro iron dialyzability from the 3 meals. NC and LC T. molitor had similar mean±SD iron content (12.0±0.1mg/100g). Geometric mean (95% CI) FIAs from the 3 test meals were 1) maize alone: 5.8% (3.2%, 10.8%); 2) maize+NC T. molitor: 5.3% (2.5%, 11.3%) and 4.1% (1.9%, 8.7%); and 3) maize+LC T. molitor: 4.6% (2.0%, 10.3%) and 4.0% (1.8%, 9.2%), for extrinsic and intrinsic labels, respectively. FIA from NC and LC T. molitor did not significantly differ, and both were lower (P<0.005) than FIA from the labeled maize porridge in the 3 meals, which did not significantly differ. The slopes of the relations between FIA and serum ferritin in the different meals and from the intrinsic and extrinsic labels did not significantly differ. T. molitor biomass does not strongly affect iron absorption when added to maize porridge. Our data suggest T. molitor iron is absorbed from the common nonheme iron pool. Native T. molitor is high in iron which is moderately well absorbed, suggesting it could be a valuable dietary iron source.This trial was registered at clinicaltrials.gov as NCT04510831.

Biodegradation of polyether-polyurethane foam in yellow mealworms (Tenebrio molitor) and effects on the gut microbiome.

Polyurethane (PU) is one of the mass-produced recalcitrant plastics with a high environmental resistance but extremely low biodegradability. Therefore, improperly disposed PU waste adds significantly to plastic pollution, which must be addressed immediately. In recent years, there has been an increasing number of reports on plastic biodegradation in insect larvae, especially those that can feed on polyethylene and polystyrene. This study revealed that yellow mealworm (Tenebrio molitor) larvae can chew and ingest polyether-PU foams efficiently, resulting in a significant mass loss of nearly 67% after 35 days at a similar survival rate compared to when fed on bran. However, polyether-PU fragments were found in the frass of T. molitor, indicating that polyether-PU biodegradation and bioconversion in intestinal tracts were not complete. The scission of ether and urethane bonds in the polyether-PU can be evidenced by comparing polymer fragments recovered from frass with the pristine ones using Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. Gel permeation chromatography suggested the release of low-molecular-weight oligomers as a result of the biodegradation, which also resulted in poor thermal stability of the polyether-PU foam as determined by thermogravimetric analysis. High-throughput sequencing of the gut microbiome revealed significant changes in the microbial community populations due to the polyether-PU diet, for example, an increase in the families Enterobacteriaceae and Streptococcaceae, suggesting that these microorganisms may contribute to the polyether-PU biodegradation.

Ultrasound-Assisted Alcoholic Extraction of Lesser Mealworm Larvae Oil: Process Optimization, Physicochemical Characteristics, and Energy Consumption.

The ultrasound-assisted extraction (UAE) of oil from lesser mealworm (Alphitobius diaperinus L.) larvae powders (LMLPs) using ethanol/isopropanol as the superior solvent was optimized. The evaluation of time (9.89–35.11 min), solvent-to-LMLPs (2.39–27.61 v/w), and temperature (16.36–83.64 °C) showed that the highest extraction efficiency (EE, 88.08%) and in vitro antioxidant activity (IVAA) of reducing power (0.651), and DPPH free-radical scavenging capacity (70.79%) were achieved at 22.5 v/w solvent-to-LMLPs and 70 °C for 22.64 min. Optimal ultrasound conditions significantly improved the EE than n-hexane extraction (60.09%) by reducing the electric energy consumption by ~18.5 times from 0.637 to 0.035 kWh/g. The oil diffusivity in ethanol-isopropanol during the UAE (0.97 × 10−9 m2/s) was much better than that of n-hexane (5.07 × 10−11 m2/s). The microstructural images confirmed the high efficiency of ethanol-isopropanol in the presence of ultrasounds to remove oil flakes from the internal and external surfaces of LMLPs. The improved IVAA was significantly associated with the total phenolic (4.306 mg GAE/g, r = 0.991) and carotenoid (0.778 mg/g, r = 0.937) contents (p < 0.01). Although there was no significant difference in the fatty acid profile between the two extracted oils, ethanol-isopropanol under sonication acceptably improved oxidative stability with lower peroxides, conjugated dienes and trienes, and free fatty acids.

Impact of defatting and drying methods on the overall liking and sensory profile of a cereal bar incorporating edible insect species

It is necessary to develop products with desirable sensory properties in order to increase the acceptance of insect-based products by Western consumers. In this work, the impact of defatting on the sensory properties of cereal bars with yellow mealworm (Tenebrio molitor) larvae, in addition to the impact of different drying methods and different species (T. molitor and house cricket Acheta domesticus) were assessed. A model cereal bar incorporating oats, dried and dehydrated fruits was developed as well as four additional formulations with insect flour: defatted (Soxhlet method with ethanol) mealworm (TM_D), microwave (TM_MW) or oven dried (TM_O) mealworm and oven dried cricket (AD_O). A panel of 99 consumers rated overall liking and willingness to buy (9-point scale), and profiled the bars using a Check-All-That-Apply ballot. The bars with defatted or microwaved mealworm had similar liking and willingness to eat scores in comparison with the control bar. Conversely, bars with oven-dried insects had worse evaluations and were associated with negative attributes related to odor and flavor, which were hampered by defatting or microwave-drying. This study highlights how different processing methods can be applied in order to increase the sensory liking of insect-based products and also provides information on their sensory characterization.

The positive impact of partial substitution of fish meal by a meal mixture of duckweed and mealworm larvae on the diets of Nile tilapia fry (Oreochromis niloticus Linnaeus, 1758)

In ordre to promote aquaculture in the south of the country, and specifically, to reduce the cost of feeding farmed fish, this study was carried out to evaluate the effect of partial replacement of fishmeal with a mixture of duckweed meal (DWM) and mealworm larvae (WLM) on growth performance, feed utilization and carcass composition of Nile tilapia. Eight-week feeding experiment was conducted on fry of O. niloticus (average initial weight: 0.87 ± 0.23 g). Four isoproteic diets (38.52 ± 0.11% crude protein) comprising control diet D0 and three test diets (D1 to D3) were formulated and tested in triplicates. To satisfy EAA requirements in test diets, the ratios 1: 5; 2: 4 ; 4: 2 between DWM and WLM were used respectively in partial replacement for fishmeal. No significant differences (P &gt; 0.05) were observed in survival, growth and feed utilization. On the other hand, the compositions of the carcasses showed strong significant differences (P &lt; 0.05) except ash contents. The carcass lipid increased proportionally with the inclusion of WLM, but the reverse was true for the moisture content. However, the high contents of retained proteins were obtained in the ratios 0 : 0 and 4 : 2 between D0 and D3. It is concluded that fishmeal could be replaced by a meal mixture of DWM and WLM up to the proportion (4 : 2, respectively) in the feed of O. niloticus without adverse effects on growth and nutrient utilization and most importantly, reduce the cost of production up to 29.8% which would have a positive impact on post-feeding and therefore the financial management of an aquaculture farm.

Growth performances, chemical composition, and microbiological loads of mealworm reared with brewery spent grains and bread leftovers

Tenebrio molitor (mealworm) larvae are one of the most intriguing edible insects, and they may be raised on a variety of substrates, including by-products, side-stream products, and former foodstuff. The substrates could affect drastically the productive performances as well as the chemical-nutritional value of the larvae. In this study we tested two main substrate ingredients, brewery spent grains (SG) and bread leftovers (B), without adding any other dry ingredients. In order to correlate the chemical composition of the substrates to the larvae characteristics, five different diets were tested as 100% of a single ingredient (SG100 and B100), 75–25% mixes (SG75B25 and SG25B75) and 50–50% mixes (SG50B50). The effects of the substrate were tested on the development rates, chemical composition, and microbial loads of mealworm larvae. The effects of fasting, washing, and cooking were also tested on the microbiological determinations. Results indicate that all the parameters were affected by the chemical compositions of the substrates. The larvae fed the higher contents of SG showed the best growth performances along with higher nutritional values. The diet with only bread (B100) showed the worst parameters, both on the growth performances and on the nutritive values. Microbial loads were also affected by the diets, with minor effects in relation to the washing and fasting procedures, while cooking drastically reduced all the microbial loads. Taking into account that the two employed ingredients were former foodstuff or by-products it is important to highlight the capacity of mealworms to positively convert side-stream materials into rich nutritional animal products. Highlights Mealworm could be proficiently reared on brewery spent grains and bread leftovers converting them into nutritional animal products. Mealworm productive performances and nutritional value could be affected by the employed substrate. Evidence of high mealworms plasticity and potential tailor made of the final outcomes.

Bioconversion Potential of Agro-Industrial Byproducts by Tenebrio molitor-Long-Term Results.

Simple SummaryDue to the forecasted overpopulation of the globe in the coming decades, the possibility of using nutrients (proteins, fats, vitamins) from sustainable sources such as insects has been discussed extensively. Although insects have been widely consumed in Asian and Latin American countries since ancient times, they are a novel food on the European continent. The first insect-based product that was allowed on the European market in early 2021 was powdered yellow mealworm (Tenebrio molitor), and later, in December 2021, frozen and dried mealworms. Agricultural byproducts are a valuable source of nutrients that can serve as a feed for insect rearing, contributing to better bioconversion of nutrients and promoting insects as a safe protein source. The present study has evaluated the bioconversion potential of yellow mealworm larvae grown on 13 diets composed of different agro-industrial byproducts. During the experiment, the larval weight gain and feed consumption were evaluated to calculate the feed conversion ratio and efficiency of ingested feed, as well as the larval development time. The results show that the best mixes for insect rearing were those that contained rapeseed meal and chicken feed, as they significantly improved the feed conversion ratio and efficiency of ingested larvae feed.The aim of this study was to compare the growth performance, feed conversion ratio (FCR), and efficiency of ingested feed (ECI) by larvae of the Tenebrio molitor beetle. The growth and development potential of the yellow mealworm was evaluated by using chicken feed (CF), rapeseed meal (RM), wheat bran (WB), and willowleaf sunflower (WS) to obtain inexpensive and various sources of feed. The results showed that the fastest growth with shorter larval development time (74.7 days) was found for insects fed a WB 100 diet. Regarding the final fresh weight of larvae, the highest values were found for larvae grown on WB diets. However, the lowest FCR (1.53 to 1.59) was found for larvae fed RM diets mixed with CF and on the control diet (CF 100). In most cases, it was found that byproduct diets mixed with CF improve the ECI of mealworms, thus contributing to an efficient bioconversion of byproducts into edible sources of nutrients. Thus, except for pure WS as a feed, these byproducts can be used to grow yellow mealworm larvae and may be added to the versatile list of substrates and feed used by small- and large-scale insect producers.

Polystyrene (PS) Degradation by Tenebrio molitor Larvae

Objectives : This study examined the degradation potential of PS by yellow mealworm larvae (Tenebrio molitor).Methods : PS degradation characteristics by mealworm larvae were investigated by supplying PS as a nutrient, and the intestinal microflora of mealworms were analyzed. Decomposition products of PS by mealworm larvae were identified by Fourier transform infrared spectroscopy (FTIR) and solid nuclear magnetic resonance (NMR).Results and Discussion : The maximum amount of PS degradation by mealworm larvae (about 14.3 mg/mealworm) was measured at 30℃ and 80% relative humidity, but the maximum peak degradation rate (0.154 mg/d/mealworm) was observed at 30℃ and 70% relative humidity. Most of the intestinal microorganisms of mealworms were identified as Proteobacteria except for some Firmicute, and new colonies such as Acinetobacter, Exiguobacterium, and Pseudomonas were appeared. A carbonyl group presumed to be a conversion product of PS (C-O-C vibration, 1118 cm;-1, O-C=O stretch, 1644 cm;-1) was observed.Conclusion : Maximum decomposition of PS by mealworm larvae was achieved at 30℃ and 80% relative humidity, and structural changes of PS were observed in the decomposition product. Isolation of the intestinal pure microorganisms contributing to PS degradation and stimulation of PS degradation by the microorganism should be conducted at a follow-up study.

Evaluation of full-fatted and hydrolysate mealworm (Tenebrio molitor) larvae as a substitute for spray-dried plasma protein diet in weaning pigs.

The goal of this experiment was to examine the effect of dietary inclusion of full-fatted mealworm larvae (FFML) or hydrolysate mealworm larvae (HML) (Tenebrio molitor) as a substitute for spray-dried plasma protein (SDPP) as a protein source on the performance and immune status of nursery pigs. A total of 150 crossbred piglets (6.48 ± 0.01 kg) were randomly allocated to 1 of 3 dietary groups in twofeeding phases: phase 1 (Days 0-14) and phase 2 (Days 15-35). Each treatment had 10 replicates with 5 pigs per replicate. The nutritious diets were: Phase 1: SDPP-CON (control-basal diet) + 6% SDPP diet; FFML-CON + 3% SDPP and 3% FFML diet; HML-CON + 3% SDPP and 3% HML diet. Phase 2: SDPP-CON (basal diet) + 3% SDPP diet; FFML-CON + 3% FFML diet; HML-CON + 3% HML diet. The inclusion of FFML or HML diet did not show significant difference but had a comparable effect as that of standard control diet containing SDPP on the growth performance, nutrient digestibility and faecal score throughout the trial. In comparison to pigs fed SDPP diet, pigs fed FFML and HML diets had similar and/or higher (p < 0.05) serum immunoglobulin (IgA and IgG) concentration at the end of phase 1 and 2. The result of the present study indictes that SDPP would be partially or fully replaced with FFML or HML to suit weaning pigs diet.

Nutritional composition and antioxidant properties of edible insects sold in Korea

Despite the importance of edible insects as future food sources, studies on their nutritional and functional properties are limited. The aim of this study was to assess the hypothesis that edible insects are nutritionally and functionally preferred and have potential for development as a food material. Seven commercially available edible insects (twin-star cricket, yellow mealworm larvae, rice locust, silkworm pupae,Baekgangjam, long-lived beetle larvae, and white-spotted beetle larvae) were purchased, and analysed for their proximate compositions, contents of nine minerals, antioxidant potential, and phenolic acid and flavonoid contents. Among the proximate components, the protein contents of rice locust,Baekgangjam, and white-spotted beetle larvae were high. The calcium, sodium, zinc, and copper contents were the highest in twin-star crickets, while the phosphorus and magnesium contents were highest in silkworm pupae, and the potassium and iron contents were highest in white-spotted beetle larvae. The total phenolic acid content was high in silkworm pupae and white-spotted beetle larvae. The flavonoid content was high inBaekgangjam. The antioxidant activity was high inBaekgangjam, white-spotted beetle larvae, and rice locust. These edible insects can be used in the development of nutritionally fortified foods for the public or in functional foods for elderly and medical patients.

Qualitative and Quantitative Detection of Mealworm DNA in Raw and Commercial Food Products Using Real-Time PCR

Considering food safety and an increasing public awareness of the ingredients, production process and origin of foods, the application of insects as food requires the development of tests for the reliable identification of their presence. The aim of the study was (1) the determination of appropriate modifications of the selected method for isolating the DNA of two life stages of mealworm, i.e., larva and adult, from commercial food products; (2) the determination of the method parameters for the qualitative and quantitative analysis of mealworm contents based on the detection of a species-specific mitochondrial DNA fragment, using real-time PCR; (3) the application of a method to test the commercial food products of mealworm. A total of nine species of adult insect were investigated (field cricket, Dubia cockroach, Madagascar cockroach, banded cricket, migratory locust, yellow mealworm, superworm, house fly and lacewing), theirlarvaes (yellow mealworms and superworms) and thirteen commercial food products (dried whole insects, powder and granules) representing various insect species and origins which were purchased from the European market. The obtained results showed that the efficiency of the modification of the DNA extraction method is dependent on the life stage of the mealworm. We proved the high sensitivity of the test, with the range of the method being 0.1–100%; we also proved the biological specificity in this range, and the linearity. The linearity of the test was also statistically verified using the Fisher–Snedecor test. One-way variance analysis showed statistically significant differences between the cT values of the two mealworm life stages studied, and similarly, between the threshold cycle (cT) values of adult forms. In contrast, for the inside group of mealworm larvae, there was no significant difference observed between the results of the cT values. The test is effective for processed food products and may be used to monitor food. The research proved the suitability of the applied method for the analysis of samples that are commercially available as food for exotic animals. The hereby-developed method is based on widely used laboratory techniques, and does not require any additional investment in equipment. The availabilityof such a methodallows for the verification of the accuracy of the declared species component of the food products.

Self-Selection of Feeding Substrates by Tenebrio molitor Larvae of Different Ages to Determine Optimal Macronutrient Intake and the Influence on Larval Growth and Protein Content.

Simple SummaryInsects are widely discussed as being an alternative source of protein and a substitute for soy- and fishmeal. However, mass production is still expensive, so means are being sought to reduce production costs. One way is to keep the costs for insect diets low. One such possibility could be the use of food industry side streams or agricultural by-products to formulate an insect diet. This study tested different substrates as feed for mealworm larvae. These included by-products from grain processing such as husks or bran, pomace and other plant components. In many studies, feed is often tested individually, during which insect larvae are given a defined substrate as a single feed or in a two-component mixture, which they either eat or reject. It is often difficult to define the right nutrient composition for creating an insect diet. Therefore, the method of self-selection was used, in order to draw conclusions about the necessary nutrient requirements, especially depending on the age of the larvae. The results showed that the most suitable substrates for rearing mealworm larvae were mainly wheat bran and flour, maize hulls, oat bran and flakes, rice flour, lupine flour and potato flakes. Irrespective of their age, the larvae required a high content of carbohydrates and proteins and a low amount of fats and minerals. Indeed, protein and fat requirements grow with increasing age. These findings contribute towards formulating diet mixtures for Tenebrio molitor larvae of different ages.Nutrient self-selection was used to determine the optimal uptake of macronutrients by the yellow mealworm (Tenebrio molitor) larvae. The selection study consisted of four combinations of eight pelleted substrates from a total choice of 25, available to the larvae in a multiple-choice arena. In order to be able to determine the nutrient requirements as a function of the larvae age, six, eight and tenweekold larvae were used for the experiment. The larvae were free to choose between the different feeds for a period of two weeks. Rearing took place at 27 °C, 75% relative humidity and under dark conditions. The optimal ratios of macronutrients were 67.3 to 71.5% for carbohydrates, 19.9 to 22.8% for proteins and 8.6 to 10.0% for lipids to ensure the best results. Biomass growth, food intake and conversion were positively influenced to a significant extent by carbohydrate intake. The protein content, too, varied according to the macronutrient intake and substrate composition; a higher protein consumption increased the larval protein content. Wheat bran and flour, oat bran and flakes, maize hulls, lupine flour and potato flakes, in particular, were considered suitable substrates for the feeding and rearing of Tenebrio molitor larvae and highlighted that these larvae preferred a grain-based diet.

The selected quality aspects of infrared-dried black soldier fly (Hermetia illucens) and yellow mealworm (Tenebrio molitor) larvae pre-treated by pulsed electric field

Drying is one of the most important steps in processing of edible insects biomass for their potential utilisation in food applications. In this study, the impact of pulsed electric field (PEF) pre-treatment (at E = 1.07 kV/cm and Wspec = 5 and 20 kJ/kg) on infrared-assisted air drying kinetics of black soldier fly (Hermetia illucens) and yellow mealworm (Tenebrio molitor) larvae has been evaluated. Moreover, microbial load and physical quality parameters of dried matter have been analyzed. The results show that PEF enhances the kinetics of water evaporation from insects biomass, especially in the range of the moisture ratio (MR) from 1.0 to 0.2. For instance, in the case of having been drying H. illucens larvae for 20 min, MR equalled 0.86, 0.75, and 0.72 for the untreated sample, 5 kJ/kg PEF-treated and 20 kJ/kg PEF-treated one, respectively. The effect of the PEF treatment was less visible in the case of H. illucens larvae and for low MR values. The PEF pre-treatment did not affect the water binding properties of dried insect biomass, regardless of species. However, the PEF pre-treated matter exhibited the same or even higher hygroscopic properties than the untreated ones. The difference in optical properties between untreated and PEF-treated samples was marginal. Nevertheless, for microbial contamination, 20 kJ/kg PEF treatment reduced the total number of microorganisms by 0.5–1.0 log cycle in comparison to the dried matter that had not been pre-treated. Nevertheless, the total number of microorganisms was too high to be feasible for food production purposes which would require additional operations to ensure food safety. Industrial relevanceThe interest in utilisation of insects as an alternative source of macronutrients for food and feed is growing tremendously. Drying is one of the most popular first steps in further processing technology applicable to insect biomass. Since air drying is one of the longest and the most energy consuming unit operation, there is a need to seek alternative methods that can be coupled with pre-treatment to enhance the process kinetics. In this paper, the combination of infrared drying of two species of insects preceded by pulsed electric field treatment has been discussed.

Growth performance and intestinal morphometric features of broiler chickens fed on dietary inclusion of yellow mealworm (Tenebrio molitor) larvae powder.

BackgroundClimate change and the lack of conventional feed ingredients have made edible insects a highly nutritious alternative to feed production. The use of insects as food may help solve socio‐economic and environmental problems around the world and be in line with the United Nations Sustainable Development Goals.ObjectiveIn this study, the growth performance and intestinal morphology of broiler chickens were evaluated under the influence of adding different levels of Tenebrio molitor larvae meal (TM meal) to their diets.MethodsOne hundred and eighty one‐day‐old broiler chickens were divided into three treatments and five replications (12 chickens/pen). The experimental diets included a control diet and treatments containing 2.5% and 5% TM meal, which were fed to birds in the starter (0–10 days) and grower (11–25 days) stages, and during the final period (26–42 days), all birds were fed a regular finisher diet.ResultsThe results showed that the diet containing TM meal had no remarkable effect on the mortality rate and feed intake of broilers (p > 0.05). In the starter period, the addition of 2.5% TM meal to broilers’ diet increased body weight gain than the control group (p ≤ 0.05). Also, the use of 2.5% TM meal in the starter period showed a significant effect on reducing the feed conversion ratio, compared to the birds fed by the control diet (p ≤ 0.05). Besides, the height of the villus, the depth of the crypt and their ratio were not altered among the different treatments (p > 0.05).ConclusionsOverall, it can be concluded that TM meal could improve growth performance in the starter period and had no negative effects on broilers' performance and intestinal morphology in all the periods of the experiment.

A new strategy using entomopathogenic fungi for the control of tree borer insects

AbstractIn order to establish a strategy for controlling pests living in trees and causing damage, injected entomopathogenic fungal conidia suspension of Beauveria bassiana into a four‐year‐old Canary Island date palm, Phoenix canariensis. As a result, B. bassiana Bb‐egfp#3 expressing green fluorescent protein was dispersed from the injection site to the top and bottom of the tree. To evaluate the insecticidal activity of the Bb‐egfp#3 injected into the tree, we released mealworm larvae (Tenebrio molitor) on the ground palm tree sample that was injected with the conidia suspension. As a result, mycosis caused by the injected Bb‐egfp#3 in the trees was generated in all cadavers. This study suggests the possibility of establishing a new control strategy against tree pests by injecting an entomopathogenic fungal conidia suspension into trees.

Management Practices Affecting Lesser Mealworm Larvae (Alphitobius diaperinus) Associated Microbial Community in a Broiler House and After Relocating With the Litter Into Pastureland.

Lesser mealworms are often found infesting production houses used to raise broiler chickens. Previous studies have investigated pathogenic microorganisms associated with the larvae, but a more thorough study relating total microbiome changes due to management procedures and flock rotations was needed. Additionally, there is a question of what microbiota are transferred into the environment when the litter, in which larvae reside, is piled in pastureland for use as fertilizer and where interactions with the soil and other fauna can occur. This study chronicled, by the 16S rRNA sequencing, the bacterial community profile of larvae in a broiler grow-out house synchronizing to when birds were added to and removed from the house over 2.5 years. The profile was found to be relatively constant despite 11 flock rotations and management disruptions, specifically litter cleanout procedures and the addition of new birds or bedding. In contrast, once removed from the controlled broiler house environment and placed into open pastureland, the substantial microbial diversity brought with the larvae showed greater fluctuation in structure with environmental conditions, one of which was rainfall. Surprisingly, these larvae survived at least 19 weeks, so the potential for moving larval-associated microbes into the environment needs further assessment to minimize the risk of relocating foodborne pathogens and also to assess those bacteria-generating metabolites that have benefits to plant growth when using the litter as a fertilizer. The characterization of their microbiome is the first step to investigating the influences of their microbes on the manmade and environmental ecosystems.