Laboratory‐adapted and wild‐type black soldier flies express differential plasticity in bioconversion and nutrition when reared on urban food waste streams

Abstract

BACKGROUNDThe black soldier fly (BSF) offers a potential solution to address the ongoing depletion of food/feed source, yet selecting effective rearing substrates remains a major hurdle in BSF farming. In an urban city, like Singapore, much of the current practices are based on rearing BSF on homogeneous waste streams (e.g., spent brewery grains, okara, etc.) because heterogeneous food wastes (e.g., mixed kitchen/canteen waste, surplus cooked food, etc.) present several operational challenges with respect to standardizing development, nutritional content, and harvesting.RESULTSIn this study, we compared two genetic strains (wild type and laboratory‐adapted line) of BSF larvae in a bioconversion experiment with diverse types of food waste (homogeneous/heterogeneous; plant/meat) and quantified the phenotypic plasticity. Our results demonstrate the different plasticity in bioconversion performance, larval growth and larval nutrition between the two BSF lines. This difference may be attributed to the selective breeding the laboratory‐adapted line has experienced. Notably, larval lipid content displayed little to no genetic variation for plasticity compared with larval protein and carbohydrate content. Despite variation in larval development, heterogeneous food wastes can produce better performance in bioconversion, larval growth, and larval nutrient content as compared to homogeneous food waste. All‐meat diets result in high larvae mortality, but larval survival could be rescued by mixing meat with plant‐based food wastes.CONCLUSIONOverall, we suggest using mixed meals for BSF larvae feeding. While targeted breeding may be a promising strategy for the BSF industry, it is important to note that selection effects on plasticity in larval nutrition should be carefully considered.This article is protected by copyright. All rights reserved.

Genetics, age, and diet influence gut bacterial communities and performance of black soldier fly larvae (Hermetia illucens)

“…The experiment employed two genetically distinct lines: a lab-adapted line (LD) that has been selectively bred on National University of Singapore (NUS) dining hall surplus food, and a wild caught BSF line (WT) to assess the in uence of lineage on gut microbiota (for further information, refer to (Zhang et al, 2023)). Genetic variability of both populations was con rmed by restriction-site associated DNA sequencing (RAD-seq; data not shown).…”

“…Diet preparation and cage set up were as previously described (Zhang et al, 2023). Brie y, four replicates were set up for each diet, and a total of 220 larvae were used for each replicate.…”

“…Bacterial community structure and larval performance Spearman's Rank correlation test was used to assess for any signi cant relationships between larval performance and gut bacterial taxa across the different diets as observed by Zhang et al (2023) (Table 3). For this, bacterial community composition at D10 was used as this closely corresponded to the larvae's harvesting age used for performance analyses (Zhang et al (2023)). Due to the identi ed genetic in uence on bacterial community composition, the two different genetic lines were analysed separately.…”

“…Hermetia illucens, commonly known as the black soldier y (BSF), has garnered attention for its exceptionally high nutritional content, sustainable and safe mode of rearing, and valuable biomaterials, which make it a promising candidate for versatile applications in the food and feed industry. It has been shown that feeding substrates, particularly their macronutrient composition (i.e., protein, fat, and carbohydrate content) in uence the development and nutritional value of BSF larvae (BSFL; e.g., protein and lipid content) (Barragan Fonseca, 2018; Zhang et al, 2023). In other insects, it has been well established that the gut microbiota, a dynamic and diverse community of microorganisms residing in the gastrointestinal tract, profoundly in uences diverse aspects of host physiology such as nutritional uptake, immunity, development, and ecological interactions (Qiao et al, 2019;Wong et al, 2017).…”

“…In a recent study, we used BSFL from two genetically variant populations fed on more than ten different diets under standardised conditions and showed that genetic variation had a signi cant effect on the plasticity in larval development and bioconversion ability as well as on larval nutritional pro les (Zhang et al, 2023). The cause of the observed variation is uncertain, leading us to the investigation of the gut microbial aspect.…”