Diet is one of the most important factors affecting the growth and lifecycle of Tenebrio molitor L. The chemical and nutritional properties of the diet of mealworms are well studied whereas its physical properties are almost neglected. This work aims to study the effects of four different particle sizes (0-0.8, 0.8-2, 2-3 and 3-4 mm) of four different feeds (wheat bran, chicken feed pellets, grounded corn kernels and alfalfa dried pellets). Four-week-old larvae were reared on the experimental substrates for four to six weeks depending on the feed. Our results indicate that particle size can significantly influence larval growth and that particles smaller than 2 mm improve larval growth on all feeds except alfalfa pellets. The maximum larval weight was slightly different for wheat bran (12%) when comparing particle sizes smaller than 2 mm with greater than 2 mm but increased up to 70% when corn kernels were used as feed. Significant differences were found between the different feeds for growth rate, larval weight and variability in larval weight. The larvae that reached an average weight of 100 mg the fastest were those reared on wheat bran followed by chicken feed and corn kernels. Larvae reared on alfalfa pellets did not reach an average weight of 60 mg. The variability in larval growth was lowest when fed wheat bran followed by chicken feed and alfalfa pellets, and the highest variability was recorded when fed corn kernels. In conclusion, both the type (wheat bran, chicken feed and corn kernels) and particle size (< 2 mm) of the feed were important determinants of larval growth.

Tomato pomace (TP), an agricultural industrial waste product from the tomato processing industry, is valorized as a rearing substrate for Tenebrio molitor (L.). This study evaluated bran-based diets with increasing tomato pomace (0%, 27%, 41%, and 100%). Protein sources, such as brewer’s spent grain and yeast, were used in TP27 and TP41 diets to ensure equal protein contents to the control diet. Results showed no different for larval and pupal weights between diets; however, the time of development significantly increases in TP100 compared to all diets. The feed conversion rate progressively increases from 2.7 to 4.3, respectively, from the control to the TP100 diet. Conversely, lycopene and β-carotene increase in the larvae. The fatty acid composition improves by increasing polyunsaturated fatty acids (mainly α-linoleic acid). Although the best nutritional quality was obtained in T100, the TP41 is the optimal diet for balance between larval performance and qualitative improvement of larvae. Therefore, tomato pomace is suitable for the formulation of mealworm diets, even in high dosages, when supplemented with sustainable protein and carbohydrate sources.

Tomato pomace (TP), an agricultural industrial waste product from the tomato processing industry, was valorized by being used as a rearing substrates for Tenebrio molitor (L.). This study evaluated bran-based diets with increasing tomato pomace (0%, 27%, 41% and 100%). Protein sources, as brewer’s spent grain and yeast, are used in TP27 and TP41 diets, respectively, to ensure equal protein content to control diet (TP0). Results showed larval survival, larval and pupal weight no different between diets; however, growth time significantly increases in TP100 compared at all diets. The feed conversion rate progressively increases from 2.7 to 4.3, respectively from TP0 to TP100. Conversely, Lycopene and β-Carotene increases in the larvae. Fatty acid composition improves by increasing polyunsaturated fatty acids (mainly -Linoleic acid). Although the best nutritional quality was obtained in T100, the TP41 is the optimal diet for balance between larval performance and qualitative improvement of larvae. Therefore, tomato pomace is suitable for the formulation of mealworm diets, even in high dosages when supplemented with sustainable protein sources.

New solutions are compulsorily needed to reconcile the enormous and ever-growing request for protein for human nutrition and, at the same time, reduce conventional meat production. This epochal challenge can find a valuable aid to a winning solution in insect rearing. The use of insects as feed and food, far from being a definitive solution to global food shortages, can offer new protein sources and perfectly fit circular economy precepts, yet more so when insects feed on by-products from the agri-food industry. In this scenario, Tenebrio molitor (TM) is a concrete alternative. Therefore, making its rearing more sustainable is a prime objective. In this paper, we evaluated the possibility of replacing usual plant sources of wet supplementation used in TM rearing with sustainable alternatives, including the cladodes of prickly pear (Opuntias ficus indica, OFI), to reduce the frequency of administration, thus minimizing related labor costs. The alternatives were tested for water content, dehydration, and shelf life to select the best-performing ones. On the selected matrices, we evaluated the preference of the larvae and their palatability because a matrix may be convenient and sustainable but not appreciated by consumers. The results showed that OFI cladodes have high moisture and a long shelf life and are appreciated by the larvae that prefer them to other matrices. Thus, OFI can replace the conventional wet source in TM rearing, at least in areas where this cactus grows wild and is not difficult to obtain.

Horticulture is mainly based on transplanting seedlings produced by specialized nurseries. The recent European authorization of frass in organic farming presents new opportunities for the development of organic seedling production. Frass, a by-product of insect farming, offers innovative solutions for this sector. It mainly consists of insect excrement, exuviae, and uningested feed. Their fertilizing and biostimulating effects have been demonstrated in various pot and field crops experiments. However, the current knowledge regarding the application of frass in seedling production remains insufficient. This study aims to assess the optimal dose of mealworm frass in germination substrates for Allium cepa L., Beta vulgaris L., and Brassica rapa L. Germination and phytotoxicity tests were carried out, with seedlings evaluated one month after sowing in substrates containing frass at concentrations of 0.5%, 1%, 2%, and 3% of frass. The germination test revealed that the dilution of the frass at 1:100 produced a phytostimulant effect on A. cepa and a moderate phytotoxic effect on B. vulgaris and B. rapa. The application of mealworm frass at a concentration of 0.5–1% was generally the most effective dose, although all doses of frass in the substrate resulted in seedlings whose root length, leaf length, number of leaves, and biomass were significantly higher than the control. In conclusion, the application of low doses of mealworm frass in organic seedling production is promising and allows the management of potential phytotoxicity.

ISHS XIV International Symposium on Apricot Breeding and Culture EVALUATION OF A LURE EFFICIENCY TOWARDS GREEN LACEWINGS IN ORGANIC APRICOT ORCHARD