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.

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

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.

The Phenolic Compounds in the Young Shoots of Selected Willow Cultivars as a Determinant of the Plants' Attractiveness to Cervids (Cervidae, Mammalia).

This study examined the phenolic acids, flavonoids, and salicylates contents in young, 3-month-old shoots (including the leaves) of willow (Salix spp.). The cultivars were selected based on experiments carried out previously in Poland on fodder and energy willows. It was found, using the HPLC-MS/MS method, that the willow cultivars analyzed from three experimental plots, contained nine different phenolic acids, five salicylates and nine flavonoids, including four flavanols (quercetin, kaempferol, taxifolin and isorhamnetin), two flavanones (prunin, naringenin), two flavones (luteolin, apigenin) and one flavan-3-ol (catechin). The contents of individual compounds were not identical and depended on the cultivar from which they were isolated. The S. laurina 220/205 and S. amygdalina Krakowianka contained the greatest amounts of phenolic acids. The lowest quantities of these compounds were found in the S. viminalis Tur, S. pantaderana and S. cordata clone 1036. The highest concentration of flavonoids in young stems was found in S. fragilis clone 1043. The S. purpurea clone 1131 contained the highest amounts of salicylic compounds. Based on the results obtained from all experimental plots, it was shown that there is a negative correlation between the extent of browsing damage and the content of helicine and salicin from the group of salicylic compounds. A similar analysis between the phenolic acid concentration and the degree of willow browsing showed a positive correlation, especially between ferulic, trans-cinnamic, and synapinic acid. A negative correlation was found between the concentration of protocatechic acid content and browsing by cervids.