The larval midgut of Hermetia illucens is characterized by a highly complex structural organization

The demand for food of animal origin is expected to increase by 70-80% within 2050, with a consequent rise in feed requirement. Another serious concern is represented by food waste disposal: in fact, it is estimated that 1.3 billion tons/year of food are globally wasted. The dipteran Hermetia illucens, also known as black soldier fly (BSF), is a promising insect species to tackle these critical challenges because of the ability of the larvae to grow on different organic substrates and their efficiency in the bioconversion process. Moreover, the high nutritional value of the larvae and pupae makes them an alternative protein source for the production of fish feed. A deep understanding of the biology of the larval midgut, which is implicated in food digestion and nutrient absorption, is essential to better comprehend the extraordinary dietary plasticity of the larva. In the present study, we performed a morphological characterization of the midgut of last instar larvae. Our results demonstrate that the larval midgut is composed of three distinct anatomical regions with different luminal pH. These regions are characterized by different cell types that accomplish digestion and absorption activities (columnar cells), acidification of the midgut lumen (cuprophilic cells), regulation processes (endocrine cells), and growth of the epithelium (stem cells). Moreover, we are investigating the expression of different enzymes along BSF midgut epithelium, which are involved in transport mechanisms. This work was supported by Fondazione Cariplo (Insect bioconversion: from vegetable waste to protein production for fish feed, ID 2014-0550).