Agri-Food Side-Stream Inclusion in The Diet of Alphitobius Diaperinus. Part 2: Impact on Larvae Composition

Abstract

Insects are gaining interest as an alternative protein source for feed/food purposes. Although the lesser mealworm (LM) is commercially produced for human consumption, published data on its nutrient composition is scarce. This study reports on LM larvae reared on 18 different diets composed of side-streams to (1) determine the nutritional composition of the larvae and (2) study the effect of dietary changes on the larval nutrient composition. The LM larvae proved to be of good nutritional value with essential amino acids profiles comparable with that of beef and linoleic acid (C18:2) was the most dominant essential fatty acids in the larvae. The side-stream based diets varied on dry matter basis in protein (16-34%) and lipid content (2-19%). The nutrient content of the larvae reared on diets that supported good growth ranged between 37% and 49% of protein, 22% and 26% of lipid and 4% to 6% of chitin on dry matter basis. No significant correlations were identified between the larval protein or lipid content and that of the diet, but it was found between the diet nutrients and larval growth. Based on larval growth data and economic considerations, diets composed of wheat middlings with a 10-15% inclusion of rapeseed meal were identified as suitable feed for LM. Highest larval yields were obtained with diets containing 15-22% of proteins and 5-10% of lipids.

Keywords: amino acids; composition of side streams; correlation; fatty acids; larval composition; lesser mealworm; lipids; nutritional value; proteins.

Figure 1

Protein content (% on dry matter basis) of the diets and corresponding larvae. Diet 2 (reference diet) is framed, capital letters represent the pairwise comparison after the Kruskal–Wallis analysis performed on the protein content of the larvae while regular letters represent the pairwise comparison after the Kruskal–Wallis analysis performed in the protein content of the diets.

Figure 2

Lipid content (% on dry matter basis) of the diet and corresponding larvae. Diet 2 (reference diet) is framed, capital letters represent the pairwise comparison after the Kruskal–Wallis analysis performed on the lipid content of the larvae while regular letters represent the pairwise comparison after the Kruskal–Wallis analysis performed in the lipid content of the diets.

Figure 3

(a) Average amino acid profile of lesser mealworm (LM) larvae reared on the diets in the current study compared to data found in literature (Source 1: [19]). (b) Comparison of the essential amino acids in LM larvae (measured in the current study) with yellow mealworm (YM) larvae [27] and beef [3], AA = amino acid, YM = yellow mealworm.

Figure 4

The relation between the dietary nutrient component and the larval yield for (a) the protein content, (b) the lipid content, (c) the carbohydrate content. Hollow bullets were indicated by their diet number. Diet 2 = reference diet.

Figure 5

(a) The relation between the larval protein and the larval yield, (b) The relation between the larval essential amino acid (EAA) content and the larval yield. Hollow bullets were indicated by their diet number. Diet 2 = reference diet.

Figure 6

Changes in cost price producing LM larvae proteins with diets 9–16 compared to the reference diet.