## 1 Introduction  
Nutrition is a major factor which influences the yield, health and profits of the animal production industry. Raw protein materials are the most expensive components in feed formulation when compared with other groups of nutrients. Therefore, protein sources of high quality with a reasonable cost should be an important consideration. Fishman and soybean meal have been used as general protein sources for the feed industry; however, these raw materials contain several disadvantages. Quality fluctuation and pathogen contamination are observed as disadvantages for fishmeal, whereas an imbalance in amino acids, low digestibility and anti-nutritional factors are presented in soybean meal. Moreover, these ingredients affect environmental deterioration [1,2]. In addition, the cost of soya and fishmeal are increasing [1,2]. Therefore, alternative protein raw materials should be sought as a solution to these problems. In recent years, there has been increasing interest in insects as an alternative sustainable protein source for animals, especially in fish, poultry and swine [3]. Their suitable chemical composition, low-cost production procedures, high feed conversion efficiency and rapid, environmentally friendly productive cycle are advantages of insect production [1,2]. Moreover, most recent experimental studies have reported several benefits on growth performance, health and product quality using insects in feed formulation at the appropriate ratio [1,2]. However, the use of insects as an alternative protein source faces many challenges, including large-scale production with stability of product quality, price competitiveness with general protein sources and country-specific regulatory barriers [3]. Fortunately, consumers accept animal products produced from insect-fed animals; however, safety and quality control should be verified and observed by professional auditors along the production process [3]. In addition, the accumulation of heavy metals in black soldier fly (BSF) larvae is a consequence of feeding BSFs with contaminated substrates containing heavy metals, which is another important consideration point [4]. Insects are considered as a novel protein source; therefore, attention must be paid to the above challenges. In addition, the number of publications on the use of insects as a protein source for animals has only increased in the last decade [1,2]. Therefore, these challenges and barriers should be addressed in the near future. Several insect species have been discovered and used with several benefits, whereas the black soldier fly (_Hermetia illucens_) has received the most attention as an alternative protein source for animals in tropical and temperate countries [5]. The large diversity of diets (organic waste: manure, food waste and industrial by-products), lower feed conversion ratio, absence of disease transmission to humans and inability to concentrate pesticides or mycotoxins from their diets in their body mass are some of the reasons driving interest in this insect species from researchers, insect farmers, animal producers and feed manufacturers [5]. Not only have waste management systems based on black soldier flies been established in several industries, but high-value products can also be obtained after the processing of products such as biodiesel, antimicrobial peptides and chitosan [5]. Consistent quality and safety are the most important considerations for black soldier fly farming and processing units. As we know, the diet is the most influential factor on the quality of black soldier fly (BSF) pupae meal [6]. However, the killing method is also a highly influential factor on BSF quality [1,7,8,9]. Heat treatment, freezing, asphyxiation and mechanical disruption are the general procedures to euthanize black soldier fly prepupae [8].