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.

House flies, Musca domestica, L., (Diptera: Muscidae) are well-known pests at animal facilities; however, they can be used for manure biodegradation. Utilizing house flies to process animal manure offers a means to recycle nutrients and reduce contaminants (e.g., pathogens and heavy metals), while also producing multiple revenue streams (e.g., protein for feed, fat for biodiesel, frass as a soil amendment). This study determined house fly larval performance on a larger scale (kilogram of wastes; thousands of larvae; single feeding) as a follow-up to a previous experiment performed at a bench-top scale (g of wastes; hundreds of larvae; incremental feeding). Four thousand larvae were fed 1 kg of swine, dairy, or poultry manure, or a control (Gainesville diet: 50% wheat bran, 30% alfalfa meal, and 20% corn meal). Peak larval weight occurred 4 days after inoculation and no significant difference in development time to first pupariation occurred across diets. However, percent survivorship to pupariation varied, with the highest occurring in Gainesville (74%), swine (73%), and poultry (67%) manure, whereas 50% survived when fed dairy manure. The highest pupal weight was found for those fed Gainesville (27 mg), and similar weights were found for those fed swine (21 mg), dairy (24 mg), and poultry (25 mg) manure. Although using house flies to manage manure has received little consideration in Western countries, other regions have this practice in place. Results may provide insight on differences between small- and large-scale studies, which is valuable for industrialization of this species for waste management and creating a more circular economy.

Adult behaviour is a growing area of interest for those researching the black soldier fly, Hermetia illucens (L.) (Diptera: Stratiomyidae), which is affected by underlying demography and spatiotemporal patterns. This greenhouse experiment examined the interaction of age-related effects that can accrue within heterogeneous breeding populations and the potential benefits of delaying an oviposition attractant in concert with restricting mean cohort age. The impetus for this investigation was because if flies are introduced into a mating-cage before old flies are removed or culled, a population of mixed-age and mating-status is created. We hypothesized this population dynamic potentially reduces quality among available mate choices, especially in small cages where flies might not be able to spatially segregate. Metrics for fitness included copulation frequency, oviposition frequency, weight of eggs produced, and hatch percentage. “Same”-aged cohorts (maximum 4 days old at introduction) performed better than highly heterogeneous (1–16 days old) “mixed” cohorts by mating 2.32-times more frequently and laying 6.58-times more eggs that were 1.17-times more fertile, despite 1.41 fewer observed oviposition events. Delaying the attractant had a significant effect on egg collection weight and led to 1.25-times higher egg yields for same-age populations compared to mixed-aged cohorts where the delaying the attractant had no significant effect. These results are likely due in part to an immediate desire to lay eggs by older females as well as haphazard egg laying in cage material, which was 2.09-times higher for mixed cohorts. The results highlight the importance of constraining the age of breeding populations and removing old adults from cages to improve yields and better manipulate behaviour. For those for whom this is logistically unfeasible, providing an attractant box initially and continuously may be the preferred method to trap more eggs from heterogeneous populations.

Adult behavior is a growing area of interest for those researching the black soldier fly, Hermetia illucens (L.) (Diptera: Stratiomyidae), which is affected by underlying demography and spatiotemporal patterns. This greenhouse experiment examined the interaction of age-related effects that can accrue within heterogeneous breeding populations and the potential benefits of delaying an oviposition attractant in concert with restricting mean cohort age. The impetus for this investigation was because if flies are introduced into a mating-cage before old flies are removed or culled, this creates a population of mixed-age and mating-status. We hypothesized this potentially reduces quality among available mate choices, especially in small cages where flies might not be able to spatially segregate. Metrics for fitness included copulation frequency, oviposition frequency, weight of eggs produced, and hatch percentage. “Same”-aged cohorts (maximum 4-d-old at introduction) performed better than highly heterogeneous (1-16-d-old) “mixed” cohorts by mating 2.32-times more frequently and laying 6.58-times more eggs that were 1.17-times more fertile, despite 1.41 fewer observed oviposition events. Delaying the attractant had a significant effect on egg collection weight and led to 1.25-times higher egg yields for same- age populations compared to mixed-aged cohorts where the delaying the attractant had no significant effect. These results are likely due in part to an immediate desire to lay eggs by older females as well as haphazard egg laying in cage material, which was 2.09-times higher for mixed cohorts. The results highlight the importance of constraining the age of breeding populations and removing old adults from cages to improve yields and better manipulate behavior. For those for whom this is logistically unfeasible, providing an attractant box initially and continuously may be the preferred method to trap more eggs from heterogeneous populations.