Larvae of the black soldier fly ( Hermetia illucens , BSFL) are rich in valuable nutrients and offer a promising alternative protein source for animal feeds. Nonetheless, there is a pressing need to improve both the productivity and quality of BSFL to ensure the viability of BSFL products and facilitating the industrial production. To fulfil the needs of different animals, it is necessary to adjust the profile of essential amino acids (EAAs) in BSFL. Insects excrete surplus nutrients to maintain homeostasis; AAs are excreted by nutrient AA transporters (NATs) in the Malpighian tubules. We aimed to modify the composition of essential AAs by silencing the NAT in Malpighian tubules of BSFL (HiNATt). Silencing HiNATt resulted in a 77.3% increase in the total AA content while 56.2% decrease in body weight. Notably, the contents of some valuable essential AAs were strongly increased (histidine, 256.8%; valine, 198.1% in total compared to the intact larva). These results suggest that inhibiting the HiNATt function could modify the amount of accumulated EAAs. This finding opens a new avenue for producing BSFL with increased nutritional value as an alternative protein source.

Larvae of the black soldier fly ( Hermetia illucens , BSFL) are rich in valuable nutrients and offer a promising alternative protein source for animal feeds. Nonetheless, there is a pressing need to improve both the productivity and quality of BSFL proteins to ensure their viability, facilitating the industrial production. To fulfil the needs of different animals, it is necessary to adjust the profile of essential amino acids (AAs) in BSFL. Insects excrete surplus nutrients to maintain homeostasis; AAs are excreted by nutrient AA transporters (NATs) in the Malpighian tubules. We aimed to modify the composition of essential AAs by silencing the NAT in Malpighian tubules of BSFL (HiNATt). Silencing HiNATt resulted in a 56.2% decrease in body weight but a 77.3% increase in the total AA content. Notably, the contents of some valuable essential AAs were strongly increased (histidine, 156.8%; valine, 98.1%). These results suggest that inhibiting the function of HiNATt could modify the composition of accumulated AAs. This finding opens a new avenue for producing of BSFL with increased nutritional value as an alternative protein source.

Optimizing the growth performance of black soldier fly ( Hermetia illucens L.) (Diptera: Stratiomyidae) larvae (BSFL) remains challenging due to limited understanding of the influence of genetic strain. Moreover, the effects of strain cannot be accurately assessed without controlling for confounding factors such as rearing density and diet fermentation variables often overlooked in previous studies. In this study, we evaluated the growth performance and density sensitivity of BSFL strains with varying degrees of inbreeding, inferred from the frequency of wild-type line introductions. Larvae were reared at defined densities using a standardized, fermentation-reduced diet to minimize microbial and nutritional variability. Daily changes in body width were modelled using logistic growth functions to estimate key parameters: asymptotic growth limit ( L ), inflection point ( m ), and growth rate ( k ). These parameters, along with fresh weight, dry weight, and body mass index at prepupa stage, were compared among strains. Correlations between density and growth traits were also analysed. Additionally, fatty acid and amino acid profiles were assessed. Results showed that strains with frequent wild-type introductions resulted in enhanced growth under low-density conditions but were more sensitive to crowding, whereas domesticated strains demonstrated greater tolerance to high density. However, highly domesticated strains exhibited significantly reduced body size and dry weight. Total fat and amino acid content remained consistent across treatments, with minor strain-specific variations on specific amino acid. These findings highlight the importance of genetic strain, density control, and standardized protocols in improving BSF rearing efficiency and ensuring reproducible research outcomes, which contributes to Sustainable Development Goal (SDG) 2, Zero Hunger, through its implications for sustainable insect-based protein production.

The black soldier fly (‘BSF’, Hermetia illucens L.) (Diptera: Stratiomyidae) is widely used in organic waste conversion and animal-feed production, yet its physiological responses to moisture variation across developmental stages remain poorly understood. This study examined stage-specific desiccation tolerance and its relationship to pupation and adult emergence. Larvae, prepupae and pupae from multiple colonies were evaluated for body water content, water-loss rate and surface-to-weight ratio under controlled ambient relative humidity conditions (50, 70, 100%). Additional experiments investigated the effects of direct larval surface moisture (dry vs. wet) of BSF larvae and ambient humidity on pupation and emergence probabilities of BSF prepupae using Cox proportional-hazard models. Water-loss rates were highest in larvae and prepupae but lowest in pupae. Prepupae with wet surfaces failed to pupate, whereas dry prepupae successfully pupated and emerged under high humidity. The results indicate that BSF pupae possess the greatest hydration-preserving capacity and that both excessive dryness and surface wetness reduce survival. Successful pupation requires a dry body surface combined with a high-humidity environment. Any low-moisture substrate capable of absorbing surface water, even simple tissue paper, can therefore substitute for conventional substrates when humidity is maintained near saturation. These findings provide practical guidance for optimising humidity management and substrate design in rearing system, and indicate the importance of clarifying the physiological mechanisms underlying BSF moisture tolerance. Such advancements will enhance black soldier fly production efficiency, supporting sustainable insect-based protein production and contributing to Sustainable Development Goal 2 (Zero Hunger) through strengthened alternative feed resources and food security.