Jonathan A. Cammack

While biotic conditions are recognised contributors to the growth and production of the black soldier fly, Hermetia illucens (L.) (Diptera: Stratiomyidae), abiotic conditions are arguably of equal or greater relevance. Shifts in key environmental conditions can be the difference between optimal production of a black soldier colony, or its collapse. As with all insects, the impact of these criteria is highly dependent on development stage of the insect and scale of application (e.g. growth chamber in a laboratory versus an industrial rearing room). Through the analysis presented herein, the impact of three abiotic factors (temperature, humidity, and photophase) on immature black soldier flies will be discussed as a means to serve as a model for investigating other abiotic factors contributing to the physiology of the species. By identifying the impact of these factors on black soldier fly development, the industry can optimise production, minimise financial investment, and enhance the economic and environmental returns of the system.

The black soldier fly ( Hermetia illucens, BSF) has emerged as an industrial insect of high promise because of its ability to convert organic waste into nutritious feedstock, making it an environmentally sustainable alternative protein source. As global interest rises, rearing efforts are also upscaled, which is highly conducive to pathogen transmission. Viral epidemics have stifled mass-rearing efforts of other insects of economic importance, such as crickets, silkworms, and honeybees, but little is known about the viruses that associate with BSF. Although it is thought that BSF are unusually resistant to pathogens because of their expansive antimicrobial gene repertoire, surveillance techniques could be useful to identify emerging pathogens and common BSF microbes. In this study, we used high-throughput sequencing data to survey BSF larvae and frass samples, and we identified two novel bunyavirus-like sequences. Our phylogenetic analyses grouped one in the family Nairoviridae , and the other with two unclassified bunyaviruses. We describe these putative novel viruses as BSF Nairovirus-like 1 and BSF uncharacterized bunyavirus-like 1. We identified candidate segments for the full BSF Nairovirus-like 1 genome using a technique based on transcript co-occurrence, and only a partial genome for BSF uncharacterized bunyavirus-like 1. These results emphasize the value of routine BSF colony surveillance and add to the number of viruses associated with BSF.

The black soldier fly (BSF), Hermetia illucens (Diptera: Stratiomyidae), has considerable global interest due to its outstanding capacity in bioconverting organic waste to insect biomass, which can be used for livestock, poultry, and aquaculture feed. Mass production of this insect in colonies requires the development of methods concentrating oviposition in specific collection devices, while the mass production of larvae and disposing of waste may require substrates that are more palatable and more attractive to the insects. In insects, chemoreception plays an essential role throughout their life cycle, responding to an array of chemical, biological and environmental signals to locate and select food, mates, oviposition sites and avoid predators. To interpret these signals, insects use an arsenal of molecular components, including small proteins called odorant binding proteins (OBPs). Next generation sequencing was used to identify genes involved in chemoreception during the larval and adult stage of BSF, with particular attention to OBPs. The analysis of the de novo adult and larval transcriptome led to the identification of 27 and 31 OBPs for adults and larvae, respectively. Among these OBPs, 15 were common in larval and adult transcriptomes and the tertiary structures of 8 selected OBPs were modelled. In silico docking of ligands confirms the potential interaction with VOCs of interest. Starting from the information about the growth performance of H. illucens on different organic substrates from the agri-food sector, the present work demonstrates a possible correlation between a pool of selected VOCs, emitted by those substrates that are attractive for H. illucens females when searching for oviposition sites, as well as phagostimulants for larvae. The binding affinities between OBPs and selected ligands calculated by in silico modelling may indicate a correlation among OBPs, VOCs and behavioural preferences that will be the basis for further analysis.

An unavoidable by-product of any animal production system, be it vertebrate- or invertebrate-based, is the manure generated by the animals themselves. In this review, we focus on the role that insects, particularly the black soldier fly Hermetia illucens (L.) (Diptera: Stratiomyidae), could play in managing the mass amount of manure produced through animal agriculture, and the subsequent commodities that could be generated by such a system. Although the focus of this review is on the black soldier fly, we postulate that other species, including the lesser mealworm Alphitobius diaperinus (Panzer) (Coleoptera: Tenebrionidae) and the house fly Musca domestica L. (Diptera: Muscidae) are also well poised to help with the challenge of managing animal manure, while generating products of value.

Meliponiculture, the keeping of domesticated stingless bees such as Geniotrigona thoracica (Smith, 1857) (Hymenoptera: Apidae), is an increasingly popular agricultural industry in Malaysia. This study reports the soldier fly (Diptera: Stratiomyidae) species of the genus Hermetia colonizing stingless bee colonies in Malaysia. The larvae were reared in the laboratory to the adult stage and identified through molecular and morphological approaches. Hermetia illucens (Linnaeus, 1758) and Hermetia fenestrata de Meijere, 1904 (Diptera: Stratiomyidae) were identified from the sample provided. Earlier records of stratiomyids in stingless bee nests were misidentified as H. illucens. This paper represents the first identified record of H. fenestrata colonizing a “spoiled” stingless bee colony. In addition, adult and larval morphological differences between both species and the roles of both species in bee nest decomposition are discussed.

Recent interest in the mass production of black soldier fly (BSF) larvae has resulted in many studies being generated. However, a majority of the studies are benchtop, or small-scale, experiments. Results generated from such studies may not translate to large-scale/industrial production. The current study was conducted at a conventional large-scale (10,000 larvae/treatment fed seven kg) to determine the impact on selected life-history traits when BSF were fed seven kg of manure (swine, dairy, or poultry) or a control diet (Gainesville diet: 50% wheat bran, 30% alfalfa meal, and 20% corn). Results showed larvae fed dairy manure took one to two days longer to develop to prepupation, with lower survivorship (45%) compared to those fed poultry or swine manure (>70%). Furthermore, the maximum larval weight was reached on day six for those fed swine manure, while other treatments achieved the maximum weight on day seven. However, larvae fed swine manure averaged 150 mg, while those fed the other diets ranged between 175 and 200 mg. Data from this study may be valuable for the industrialization of BSF. Companies using a scale varying from previously published work, including this study, should conduct pilot studies to optimize their system prior to implementation.

Few studies have examined the competitive interaction between the house fly (HF) and the black soldier fly (BSF). The fact that the BSF deters HF oviposition is widely cited in BSF literature, but this interaction has not been assessed in over three decades. In this study, the competitive interaction of BSF and HF larvae was observed on fresh (day 0) and aged poultry manure (manure aged for two, four, six, or eight days). Specifically, a priority effect study was conducted to determine if colonization sequence influences time to first pupariation (HF) or pre-pupation (BSF), survivorship, and weight. Results show >70% of HFs reached pupariation in all treatments except when placed on manure eight days after the initial inoculation with BSF. However, age of the resource negatively impacted time to first pupariation and puparium weight when HFs were reared alone or introduced two to eight days after BSF. No BSF pre-pupae resulted from treatments in which HFs were the pioneering species. BSFs reached the highest percent pre-pupation when reared alone on fresh manure, but BSFs may be more susceptible to the negative impacts of an aging resource, as no pre-pupae were observed when provided with six- or eight-day-old manure. Similar to HFs, age of the resource may have impacted development and survivorship; other factors such as moisture content, chemical composition, and amount of resource provided may have also impacted our results. These data may be useful in implementing BSFs as biological control agents of the HF, as well provide valuable information for facilities mass-producing HFs or BSFs for food or feed.

Structural changes and growth of animal production systems have resulted in greater volumes of manure. Current manure storage methods pose a potential environmental threat. Lessening these issues is a key concern for the animal production industry. The primary aim of this research was to evaluate black soldier fly (BSF) performance when fed poultry, swine, or dairy manure at different rates (18 or 27 g/2 d until 40% prepupation). The results indicated that larvae fed with the control diet (Gainesville diet) were the heaviest (+31–70%); however, for other life-history traits, those fed the higher feed rate of poultry manure produced comparable results to the control. Larvae fed more resource, regardless of manure type, weighed more as larvae (+3–9%), pupae (+22–48%), and adults (+18–42%), developed faster (up to 3–4 d), had a higher percentage reach the prepupal stage (+2–16%), lived longer as adults (+1 d), and converted more resource to biomass (up to 1% more) than those fed at the lower rate. Yet, no difference was detected in dry matter (DM) reduction across feed rate for a given manure type. Based on these results, all three manure types can be digested by black soldier fly larvae, thus demonstrating their potential for waste management.

For the past 30+ years, the black soldier fly Hermetia illucens (L.) (Diptera: Calliphoridae) has been studied intensively as a means for addressing two issues of global concern: organic waste management, and alternate protein production. The larvae are voracious, generalist feeders, able to consume a wide variety of materials ranging from plant matter (fruits, vegetables, grains, etc.) to animal matter (tissue, manure, etc.), and transform these materials into body mass that can be upwards of 45% protein and 35% fat. Additionally, this is the only insect species that has been approved for use as an animal feed in the United States (for salmonid fish) and Canada (for salmonid fish and broiler poultry). Maintaining a robust population to supply an operation with the larvae necessary for waste management and protein production is of utmost importance for entities interested in mass producing black soldier flies, while at the same time ensuring consistent larval output (in both quantity and quality). This chapter focuses on methods used for rearing black soldier flies, as well as challenges associated with mass production for waste management and protein production.