The yellow mealworm (Tenebrio molitor) is one of the most produced insects for food and feed globally. Despite being commercially produced, little is known about one of its most basic properties – its genome and how this genome dictates its phenotypes. The phenotype of a particular insect is integral to its use in mass production: one must understand how quickly it can grow, how big it can get, how fecund it can remain, and how resilient it is to perturbations in its environment all in an effort to optimally produce safe and reliable insects for food and feed. We generated a genome of a strain of the yellow mealworm using linked-read technology (10X Genomics). This technology is a combination of short read sequencing technology that is accurate and reliable with long-read capabilities, resulting in a preliminary draft genome that encompasses ~ 90% of its gene content according to conserved homologous database queries (with more than 20,000 genes assembled). The genome (312 Mb), with more than half its genome present in contigs that are 40,000 bp or longer, allows us to immediately understand the gene structures, but also to delve into regulatory regions in the genome in the future. Changes in these regulatory sequences are what will provide the greatest value to the industry when correlated to phenotypic properties of the insects, leading to a more efficient selection of optimal insects for mass production. Currently, this is often done using selective breeding which has the potential to introduce some troublesome (piggybacked) traits that have the potential to offset its entire production value. This resource will allow all in the industry to compare and contrast their strains without needing to sequence whole genomes, and allow the industry to move forward at the same pace as other agriculturally important products.

The evaluation of alternative feeding substrates for the mass-rearing of insects is one of the main current research priorities of the insect sector. These substrates should be preferably by-products or waste-streams that can be upcycled by insect bioconversion, with low cost, and should ideally be locally produced. In Greece, various by-products are produced as a result of several agro-industrial processes and are currently either used as low cost feed for livestock animals or discarded as waste. In this study, we evaluated the suitability of 11 Greek agricultural by-products (sugar beet pulp meal, sunflower meal, cotton cake, cotton seed meal, by-products of the seed cleaning process of barley, oats, pea and vetch) for the rearing of larvae of the yellow mealworm, Tenebrio molitor. In a first series of bioassays, we evaluated the suitability of each by-product alone. Briefly, plastic cylindrical vials were filled with 20 g of each substrate and then 20 newly emerged T. molitor larvae were introduced into the vials. Larvae were allowed to feed undisturbed ad libitum at 26 °C and 55% relative humidity for a 4-week period. After this interval, larval survival and weight were recorded. Afterwards, larvae were returned to their corresponding vials, provided with new substrate (20 g), and returned to the growth chamber for another 4-week period. This process was repeated for two more 4-week periods completing a total of three 4-week periods of development. Wheat bran served as a “control diet”. In a second series of bioassays, the suitability of mixtures of each by-product with wheat bran (1:1) was evaluated, following the experimental design described above. Finally, based on the results of the previous two series of bioassays and the nutritional composition (protein, lipid, carbohydrate content, ash and energy) of the by-products, isonitrogenous diets based on the best performing by-products were designed and evaluated. According to our results, the cereal by-products tested, i.e. barley and oats by-products, were highly suitable for the rearing of T. molitor larvae and could be used as the core ingredient of T. molitor diets. Our findings contribute to implementing insect farming in the circular economy at a local level. This work was supported by a postdoctoral scholarship program implemented by University of Thessaly and funded by Stavros Niarchos Foundation.

Insects are a sustainable and nutritious alternative protein source, and crickets are an economically important insect in the North American entomophagy industry. A primary goal of agricultural research is to increase yield. Increased body size in cricket farms is desired, but we have little knowledge on how to do it at such a large scale. Diet supplementation using honey bee royal jelly is a potential solution, as there is evidence that royal jelly enhances body size of other insect species including a single orthopteran. The mechanisms behind how royal jelly does this remain unclear. To determine the effect of royal jelly on a farmed cricket species, 96 Gryllodes sigillatus were obtained from a local Canadian cricket farm, individually housed, and split into two treatment groups: half were reared on a commercially available cricket diet, while the other half were reared on the same diet mixed with 15% w/w fresh royal jelly. Body size and mass measurements were taken weekly for six weeks (approximate time to adulthood). We discovered a female-only effect of royal jelly on G. sigillatus: females fed the royal jelly diet grew to be 21% heavier, and this effect was driven by significantly longer abdomens containing 66% more eggs each compared to those fed the basal diet. We are now replicating this experiment in a simulated farm environment to determine whether increased female fertility from royal jelly persists in high-density rearing environments like an active commercial farm.

Black soldier fly larvae (BSFL, Hermetia illucens L. 1758) are increasingly produced as animal feed around the world. In Europe, as BSFL should be used for fish production, it is interesting to characterize their fatty acid (FA) composition but also to understand the underlaying biochemical pathways of FA production for potential modulation. In the present study, 3 batches of 50 larvae (n=3) were produced on 4 different diets: 1. 100% of chicken feed with 40% of H2O (CF); 2. 40% of chicken feed and 60% of flax cake with 40% of H2O (FL); 3. CF with 40% of deuterated water D2O (CFD) and 4. FL with 40% of D2O (FLD). Growing parameters as developmental time (DT) and individual weight (IW) were collected throughout BSFL development. Before pupation, BSFL were collected and, following a folch extraction, fatty acid methyl esters of each larval batches were analyzed by gas chromatography coupled with mass spectrometry. The DT and LW of BSFL were significantly impacted by the presence of deuterated water in diets (CFD: 20 days and 121.27 mg ± 6.46c; FLD: 28 days and 116.57 mg ± 6.56c; F12 = 151.40; p < 0.001). Concerning the two others diets, the DT were equal (9 days) while the LW was greater for CF (251.16 mg ± 4.47a) than for FL (200.04 mg ± 6.17b). BSFL fed with FL show higher levels of α-linolenic acid (C18:3n3) than BSFL fed with CF (respectively 0.70 % ± 0.03 and 5.64 % ± 1.38). The analysis of FA from BSFL fed with deuterated diets shows only a deuterated form of C10:0 and C12:0 and a partial percentage of deuterated C14:0, C16:0, C16:1, C18:1n9 and C18:2n6. The complete deuteration of these 3 FA were expected as they were not present in diets and confirm the reliability of the method. When fatty acids are found in the two forms, it appears that some of these were produced via biosynthesis pathways while another proportion of the FA was accumulated from the diet. Proportions of C12:0 were reduced in BSFL fed with deuterated diets in favor of C18:1n9 (approximately from 20% in “normal” diets to 30% in deuterated diets). This trend has been verified in other tests carried out with flax-based diet in our laboratory, perhaps due to a better assimilation of this FA from flax-based diet by BSFL. Finally, no deuterated C18:3n3 were found in BSFL fed with FLD confirming that the BSFL are not able to produce this FA but can simply accumulate it. In order to reduce the disturbance of larval development highlighted by BSFL life history traits, it would be interesting to incorporate only one deuterated fatty acid among those shown in this work as biosynthesized and to monitor its use by the BSFL.

The Black Soldier Fly (BSF) rearing system realized by the FORWARD project in Sidoarjo, Indonesia uses pupation (dark) cages and oviposition (love) cages. Flies emerge from pupae inside a dark cage and are then harvested into love cages by connecting the cages and attracting the flies using a light source. The current setup utilizes fly densities of 7,000-8,000 flies in each love cage (70x70x150 cm). When considering limited space at small decentralized BSF facilities, it is a key objective to optimize egg productivity in relation to fly density in love cages. This trial tested thirteen different fly densities in love cages. These densities ranged from 3,000-15,000 flies with increments of 1,000 and a triplet setup for each density setting. Prepupae, with weights varying between 113±4.7 mg and 164±20.7 mg, were added into pupation crates of which 16 were placed inside each dark cage containing a number of prepupae ranging from 120,000-320,000. After the love cages were stocked with the defined density of flies, they were placed in a shaded area, which received abundant indirect natural light. Three batches of 20 flies were randomly extracted from each love cage. For each sample of 20 flies, the sex ratio and the average weight were investigated. Preliminary sampling results show that on average, flies weighed 62.5±2.6 mg each at point of harvesting. Each love cage included a container with attractant substrate (a mixture of dead flies, treatment residue and fermented fruit water), wooden egg media, a shade box and a water container. Relative humidity and temperature were recorded both in the dark cage room and the surrounding area of the love cages during the complete duration of the trial. After four days, the eggs produced were harvested and weighed and each love cage was dismantled. The tested range could show that with higher density of flies in love cages, a twofold increase of egg production per square meter can be realized compared to the current setup, thus reducing the space footprint and labour workload. With the triplet setup for each tested density it was further possible to obtain information on how the sex ratio impacts on the egg production performance.