Valorization of Agricultural Side-Streams for the Rearing of Larvae of the Lesser Mealworm, <i>Alphitobius diaperinus</i> (Panzer)

During the last decade, insects have shown up as a promising answer to the increasing animal protein demand for a continuously growing human population. A wide spectrum of substrates of plant origin can be currently used as insect feed; the sustainability of insect rearing though greatly increases when organic side-streams and wastes are valorized and upcycled through their bioconversion with insects. Additionally, the exploitation of low-cost organic residues as insect feed can also significantly suppress the rearing cost and, consequently, the price of the insect meal. In this context, the aim of our work was to evaluate organic side-streams, generated through several agro-industrial processes, as feeding substrates for the larvae of the lesser mealworm, Alphitobius diaperinus. In a laboratory trial, eleven agricultural side-streams were provided to larvae singly to assess their potential to support complete larval development, whereas in the second trial, larvae were fed two groups of isoproteinic diets consisting of the side-streams that performed well in the first trial. Our results showed the suitability of several agricultural side-streams as feed for A. diaperinus larvae, e.g., barley by-products (classes I and II), sunflower meal, cotton cake and oat sidestream, which, when fed singly, efficiently supported larval growth, resulting in high survival rates and final larval weights, comparable to the control. Similarly, several of the side-streams-based diets tested were shown to be suitable for A. diaperinus rearing. These results aim to contribute to the utilization of agricultural side-streams singly or in composed diets for the rearing of A. diaperinus larvae

Factors Affecting Adult Captures of the Cotton Bollworm, Helicoverpa armigera (H&uuml;bner) (Lepidoptera: Noctuidae) in Pheromone-Baited Traps

The effects of funnel-trap color, trap height and pheromone formulation on the adult captures of the cotton bollworm, Helicoverpa armigera (H&uuml;bner) (Lepidoptera: Noctuidae) were evaluated in traps that were suspended in cotton fields in central Greece. Briefly, in a first trial, the efficacy of funnel traps of three different colors, i.e., green, striped (with black and white stripes) and white, was comparatively evaluated, whereas in a second trial green funnel traps were placed at three heights, i.e., 30, 60 and 90 cm from the ground. Finally, in a third trial we tested the efficiency of green funnel traps with three commercially available pheromone lures. Considering the overall captures, trap color and pheromone formulation affected male captures, whereas trap height had no influence. Captures notably increased in all traps from late August to mid-September. In total, the white funnel trap captured more moths than the green or striped funnel traps. Placement of the traps at different heights did not significantly affect captures, but seasonal differences were observed at individual dates during the trapping period. Barrettine&rsquo;s pheromone lure provided significantly more captures than the other two (Russell, Tr&eacute;c&eacute;) in some of the trap-check dates. The results can be further utilized in the monitoring protocols of H. armigera in cotton fields

Rearing Tenebrio molitor and Alphitobius diaperinus Larvae on Seed Cleaning Process Byproducts

The exploitation of agricultural byproducts and organic side-streams as insect feeding substrates is advantageous for insect farming both from an economic and a sustainability perspective. In this context, in the present study we evaluated the suitability of ten byproducts of the cereal and legume seed cleaning process for the rearing of larvae of the yellow mealworm, Tenebrio molitor, and the lesser mealworm, Alphitobius diaperinus. Byproducts were offered singly to 20 T. molitor and 50 A. diaperinus larvae with provision of carrots as moisture source. After four weeks of undisturbed development, larval weight and survival was evaluated biweekly until pupation. Feed utilization and economic feasibility parameters were determined for each byproduct at the end of the bioassays. Our results show the suitability of several of the byproducts tested for the rearing of T. molitor and A. diaperinus larvae. The best results though among the byproducts tested in terms of larval growth and survival, development time and feed utilization were obtained with larvae fed with lupin and triticale byproducts, which efficiently supported complete larval development. The results of our study aim to boost the integration of circular economy strategies with insect farming practices

Effect of Nitrogen on Stored-Product Insect Control at Industrial Scale

In this study, we evaluated the insecticidal effect of nitrogen against Sitophilus granarius (L.), Sitophilus oryzae (L.), Rhyzopertha dominica (F.), Prostephanus truncatus (Horn), Tribolium confusum Jacquelin du Val, and Oryzaephilus surinamensis (L.). Four trials were conducted in chambers containing flour in bags or sacks with >99% nitrogen level. Adults of all the above species, as well as immature life stages (eggs, larvae, and pupae) of T. confusum were used in the trials. Our results showed that nitrogen caused high mortality for all species and life stages tested. Some survival was recorded for R. dominica and T. confusum pupae. Low progeny production was recorded for S. granarius, S. oryzae, and R. dominica. In conclusion, our trials indicated that a high nitrogen environment can provide satisfactory control of various primary and secondary stored-product insect species

Insect-Based Feed Ingredients for Aquaculture: A Case Study for Their Acceptance in Greece

Although the inclusion of insects in fish diets is officially allowed in the EU since 2017, insect-based aquafeeds have not been widely adopted by the European aquaculture sector. In order to investigate the perceptions related with adoption trends, it is critical to explore the beliefs of people associated with the aquaculture sector on the use of insects in farmed fish diets. A survey was conducted among 228 participants of an aquaculture conference to explore their perceptions on the inclusion of insect meal in fish diets. Additionally, we investigated the attitudes of nine companies operating in the aquaculture and aquafeed sector in Greece that attended the conference towards this direction. The findings of the conference survey provide evidence that there is a wide-range awareness and acceptance regarding the use of insect-based feeds in farmed fish diets among the respondents. This is mainly driven by the expectations for the decline in fishing pressure on wild fish stocks, the reduction of the ecological footprint and the enhancement of the sustainability of the aquaculture sector. The results of the stakeholder survey show that six out of the nine companies that participated in the survey are favorably disposed towards the use of insect-based feeds. Specifically, four of them stated that they would produce or use aquafeeds based on insects. However, the results highlight the need for further research on the implementation of the wider adoption of insect-based feeds in aquaculture. The present study provides some first insights into the use of insect-based aquafeeds in Greece, for which there are no data available

Evaluation of various commodities for the development of the yellow mealworm, Tenebrio molitor

Abstract We evaluated the suitability of forty-four commodities (i.e., cereal flours and meals, non-flour, cereal commodities, legumes and various commodities of vegetative and animal origin) as oviposition and feeding substrates for the yellow mealworm, Tenebrio molitor. Τen T. molitor adults were introduced in plastic vials containing 30 g of each commodity. At the end of the 1 week period, all adults were removed, and mortality was determined; then the vials were further incubated for additional 9 weeks. After this time, the vials were opened, and the larvae of each vial were separated from the feeding substrate, counted and weighed as a group. The efficiency of ingested food conversion was calculated for each substrate. Finally, proximate composition was calculated to determine the nutrient components of the feeding substrates tested and the T. molitor larvae that fed on various selected substrates. In general, adult reproduction was clearly favoured by most amylaceous substrates tested, which was in contrast to the tested legumes on which fewer offspring were produced. Similar effects were observed for larval development. Feeding on selected substrates exerted an impact on the nutrient composition of T. molitor larvae, with a high protein content of the substrate usually resulting in a high protein content of the larvae

Influence of Temperature, Relative Humidity and Protein Content on the Growth and Development of Larvae of the Lesser Mealworm, Alphitobius diaperinus (Panzer)

The human population is rapidly growing, subsequently leading to an increase in food and protein demand. Therefore, alternative protein sources have to be evaluated as food and feed. Among the most promising alternative protein sources with significant advantages are insects. Nevertheless, insect rearing conditions have to be optimized prior to insect mass production. In the present study, using laboratory bioassays, we evaluated the effect of several biotic and abiotic factors on the development of the larvae of the lesser mealworm, Alphitobius diaperinus (Panzer). In the first series of bioassays, we investigated A. diaperinus larval growth at three temperatures (25, 30 and 32 °C) and two relative humidity (r.h.) levels (55 and 75%). Furthermore, in the second series of bioassays, the larval growth was assessed on wheat bran-based substrates with different percentages of yeast, i.e., 0%, 10%, 17.5%, 25%, 32.5% and 40%. According to our results, the temperature was shown to be highly important for larval development, with A. diaperinus larvae performing better at the higher temperatures tested, i.e., 30 and 32 °C. In contrast, relative humidity did not have a significant effect on A. diaperinus growth, at least for the relative humidity levels tested. Finally, the increase in the percentage of yeast in the diet increased larval growth, development and survival. Our study aims to highlight the significance of several biotic and abiotic factors for the rearing of A. diaperinus larvae, providing parameters that can be further utilized in mass rearing protocols of this species

Insect-Based Feed Ingredients for Aquaculture: A Case Study for Their Acceptance in Greece

Although the inclusion of insects in fish diets is officially allowed in the EU since 2017, insect-based aquafeeds have not been widely adopted by the European aquaculture sector. In order to investigate the perceptions related with adoption trends, it is critical to explore the beliefs of people associated with the aquaculture sector on the use of insects in farmed fish diets. A survey was conducted among 228 participants of an aquaculture conference to explore their perceptions on the inclusion of insect meal in fish diets. Additionally, we investigated the attitudes of nine companies operating in the aquaculture and aquafeed sector in Greece that attended the conference towards this direction. The findings of the conference survey provide evidence that there is a wide-range awareness and acceptance regarding the use of insect-based feeds in farmed fish diets among the respondents. This is mainly driven by the expectations for the decline in fishing pressure on wild fish stocks, the reduction of the ecological footprint and the enhancement of the sustainability of the aquaculture sector. The results of the stakeholder survey show that six out of the nine companies that participated in the survey are favorably disposed towards the use of insect-based feeds. Specifically, four of them stated that they would produce or use aquafeeds based on insects. However, the results highlight the need for further research on the implementation of the wider adoption of insect-based feeds in aquaculture. The present study provides some first insights into the use of insect-based aquafeeds in Greece, for which there are no data available

Compositional, volatile, and structural features of Hermetia illucens (black soldier fly) flours: The effect of population and life stages

The scope of the present study was to study the effect of different populations of Hermetia illucens, commonly known as black soldier fly (BSF), on the major components and volatile composition of the derived freeze-dried flours. Potential differences in the composition of different life cycle stages of BSF, i.e., larvae and pupae, were also investigated. The flours obtained from larvae of two BSF populations from Greece (GR) and Portugal (PO) (L-GR and L-PO, respectively) demonstrated similar major chemical compositions. Pupae (Pu-PO) were richer in chitin compared to larvae. Differences were spotted in their fatty acid profiles and volatile fractions. The saturated/unsaturated lipid fraction ratio was 1.5 in L-GR, higher in L-PO (2.5), and even higher in the case of Pu-PO (4.0). Seventeen (17) compounds were detected in the volatile fraction of the Pu-PO samples and 24 in the volatile fraction of the L-GR and L-PO samples. Notably, dodecanoic acid ethyl ester was the predominant volatile compound in all samples. The proteins of both larvae and pupae were dominated by β-sheet structures. The present study's findings are valuable for designing food or feed products based on BSF components and could be important for applying suitable manufacturing and processing procedures