The larvae of the black soldier fly, Hermetia illucens, are well known as decomposers of organic waste due to their ability to grow and develop on a wide range of substrates. Despite the great interest on the use of these larvae for bioconversion, there is a lack of knowledge about the immune system of this insect. In the present study we analyzed different mechanisms involved in cellular and humoral response of H. illucens larvae. In particular, we performed a morphological analysis of hemocytes, before and after injection of a mix of Gram positive and Gram negative bacteria, and evaluated their phagocytosis and encapsulation capability. Moreover, we investigated the activity of key components of the humoral immune response, i.e., phenoloxidase system, lysozyme, and antimicrobial peptides (AMPs). Our results show a strong reactivity of hemocytes in infected larvae, in which cell proliferation, phagocytosis, and encapsulation rapidly occur after the administration of bacteria to the larva. The humoral response mainly involves lysozyme activity and the onset and recruitment of AMPs, while proPO system seems to be inhibited in infected larvae. This study provides information about the H. illucens larval immune system and opens up the possibility to improve the quality of H. illucens larvae during mass rearing through a modulation of the immune response.
Analysis of cellular and humoral immune response in Hermetia illucens larvae.
D Bruno;A Montali;M Mastore;A Grimaldi;Brivio M F;G Tettamanti
2020-01-01
Abstract
The larvae of the black soldier fly, Hermetia illucens, are well known as decomposers of organic waste due to their ability to grow and develop on a wide range of substrates. Despite the great interest on the use of these larvae for bioconversion, there is a lack of knowledge about the immune system of this insect. In the present study we analyzed different mechanisms involved in cellular and humoral response of H. illucens larvae. In particular, we performed a morphological analysis of hemocytes, before and after injection of a mix of Gram positive and Gram negative bacteria, and evaluated their phagocytosis and encapsulation capability. Moreover, we investigated the activity of key components of the humoral immune response, i.e., phenoloxidase system, lysozyme, and antimicrobial peptides (AMPs). Our results show a strong reactivity of hemocytes in infected larvae, in which cell proliferation, phagocytosis, and encapsulation rapidly occur after the administration of bacteria to the larva. The humoral response mainly involves lysozyme activity and the onset and recruitment of AMPs, while proPO system seems to be inhibited in infected larvae. This study provides information about the H. illucens larval immune system and opens up the possibility to improve the quality of H. illucens larvae during mass rearing through a modulation of the immune response.
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