Vol.:(0123456789) 1 3 https://doi.org/10.1007/s42690-021-00427-5 ORIGINAL RESEARCH ARTICLE Heavy metal bioaccumulation in prepupae of black soldier fly Hermetia Illucens (Diptera: Stratiomyidae) cultured with organic wastes and chicken feed Marilyn C. Elechi 1,3  · Kehinde A. Kemabonta 1,3  · Sylvester S. Ogbogu 2  · Ijeoma C. Orabueze 1  · Fouad A. Adetoro 1  · Henry A. Adebayo 1  · Toyin M. Obe 1 Received: 19 June 2020 / Accepted: 8 January 2021 © African Association of Insect Scientists 2021 Abstract Larvae of the black soldier fy (BSF), Hermetia illucens can be reared in large quantities on organic wastes. The larvae are harvested at the prepupal stage and used as feed for poultry and aquaculture. BSF farms in Nigeria make use of a combination of chicken feed and organic waste in the rearing processes. Chicken feed and organic waste can contain varying levels of heavy metals, which may accumulate in the larvae. The aim of this study was to determine bioaccumulation of heavy metals, cadmium chromium, copper, lead, and zinc, in prepupae cultured on chicken mash and various types of organic wastes (food waste, brewery waste, and fruit waste). Bioaccumulation of a particular heavy metal occurs when the concentration of the metal is higher in the harvested prepupae than in the feed substrates (Factor > 1). The results of the study showed that bioaccumulation was more likely to occur in brewery waste than in the other substrates, while bioaccumulation factors greater than one were reported for three of the fve heavy metals (copper, lead and chromium). All heavy metal concentrations reported in the study were below the safe limits for use in animal feeds. The use of organic waste rather than chicken mash for rearing BSF larvae should be considered in Nigeria. However, there must be quality control measures in place to ensure that the larvae’s propensity for accumulating heavy metals are contained. Keywords Entomophagy · Insect · BSF · Feed · Sustainability Introduction The world’s rapidly increasing population has created issues such as waste management and food security. This is seen very clearly in Nigeria, where the metropolitan city of Lagos churns out tens of thousands of tons of solid waste annually from anthropogenic activities, including domestic waste and market waste. Larvae of the black soldier fy (BSF), Hermetia illucens are detritivorous, degrading organic waste by feeding on it (Diener et al. 2011). They are found in warm climates, usually in tropical or subtropical ecozones across all continents except Antarctica (Diclaro and Kaufman 2018). Females lay hundreds of eggs at a time, which hatch into larvae that can grow up to 27mm in length (Sheppard et al. 2002) As it takes only 14 days under optimal conditions to achieve complete development, H. illucens larvae can be reared in large quantities and applied to organic waste (Diener et al. 2011). Once they reach the prepupal stage, the larvae can be harvested and processed as feed for poultry and aquaculture (Diener et al. 2015). BSF larvae are rich in protein, fat, and micronutrients, and can serve to complement increasing expensive protein sources such as fish and soybean meals often used in livestock feed production (FAO 2004; St-Hilaire et al. 2007; Sealey et al. 2011). Compared to other forms of livestock, the culturing of these insects requires few natural resources, while yielding higher protein content per body mass (Gahukar 2016). Greenhouse gas emissions from BSF farming are near negligible, and farmers can culture the larvae for use in their own fsh or poultry farms, thereby reducing their cost of feed * Kehinde A. Kemabonta kkemabonta@unilag.edu.ng 1 Department of Pharmacognosy, Faculty of Pharmacy, University of Lagos, Lagos, Nigeria 2 Aquatic Entomology, Obafemi Awolowo University, Ife, Nigeria 3 Department of Zoology, University of Lagos, Lagos, Nigeria / Published online: 8 March 2021 International Journal of Tropical Insect Science (2021) 41:2125–2131