Characterization and mode of action analysis of black soldier fly (Hermetia illucens) larva‐derived hemocytes. (22nd December 2021)

• Record Type: Journal Article
• Authors: von Bredow, Yvette M.; Müller, Ariane; Popp, Philipp F.; Iliasov, Denis; von Bredow, Christoph‐Rüdiger
• Is Part Of: Insect science. Volume 29:Number 4(2022)
• Page Start: 1071
• Page End: 1095
• Publication Date: 2021-12-22
• Subjects: black soldier fly (Hermetia illucens) -- cellular immunity -- crystal cell -- hemocyte types -- immunity of economically important insects -- microbe phagocytosis -- plasmatocyte; Insects -- Periodicals; Entomology -- Periodicals; 595.705
• DOI: 10.1111/1744-7917.12977
• Languages: English
• ISSNs: 1672-9609

Abstract

Abstract: With the growing importance of the black soldier fly ( Hermetia illucens ) for both sustainable food production and waste management as well as for science, a great demand of understanding its immune system arises. Here, we present the first description of the circulating larval hemocytes with special emphasis on uptake of microorganisms and distinguishing hemocyte types. With histological, zymographic, and cytometric methods and with a set of hemocyte binding lectins and antibodies, the hemocytes of H. illucens are identified as plasmatocytes, crystal cells, and putative prohemocytes. Total hemocyte counts (THC) are determined, and methods for THC determination are compared. Approximately 1100 hemocytes per microliter hemolymph are present in naive animals, while hemocyte density decreases dramatically shortly after wounding, indicating a role of hemocytes in response to wounding (and immune response in general). The determination of the relative abundance of each hemocyte type (differential hemocyte count, DHC) revealed that plasmatocytes are highly abundant, whereas prohemocytes and crystal cells make up only a small percentage of the circulating cells. Plasmatocytes are not only the most abundant but also the professional phagocytes in H. illucens . They rapidly engulf and take up bacteria both in vivo and in vitro, indicating a very potent cellular defense against invading pathogens. Larger bioparticles such as yeasts are also removed from circulation by phagocytosis, but slower than bacteria. This is the first analysis of the potent cellular immune response in the black soldier fly, and a first toolbox that helps to identify hemocyte (types) is presented. Abstract : Graphical Abstract: The first detailed description of circulating hemocyte types of Black Soldier Fly ( Hermetia illucens ) by morphological, cytometrical, and functional characteristics reveals three distinct hemocyte types. The most abundant cell type (∼98%) are the plasmatocytes, which appear to be highly variable in their shape and size and are the professional phagocytes taking up bacteria and yeasts. Crystal cells contain crystalline inclusions and possess phenoloxidase activity, and like the rare putative prohemocytes, they do not participate in microbe uptake.