Bioscience Methods 2024, Vol.15, No.6, 302-314 http://bioscipublisher.com/index.php/bm 308 Figure 2 A simplified overview of haemocytes and their contribution to insect immunity and wound healing. Haemocytes include plasmatocytes, granulocytes, lamellocytes and oenocytoids/crystal cells. Cellular immune responses to microbial or parasitic infection are graphically depicted. These include encapsulation by lamellocytes, nodulation, phagocytosis and haemolymph clotting by plasmatocytes, and melanization by crystal cells and oenocytoids. The contribution of haemocytes and fat body in the prophenoloxidase (PPO) cascade activation is also portrayed, in addition to role of epithelia in immunity. Cytotoxic species released in epithelia include Reactive Oxygen Species (ROS), Reactive Nitrogen Species (RNS) and quinones. Upon infection, the fat body induces the production of clotting factors and serine proteases. The latter regulates the melanization response. Microbial recognition induces the expression of peptidoglycan recognition protein (PGRP), which regulate the activity of proteases that control the prophenoloxidase (PPO) cascade and melanization response (Adopted from Eleftherianos et al., 2021a) The study of Eleftherianos et al. (2021a) outlines the role of different hemocytes, such as plasmatocytes, granulocytes, and crystal cells, in insect immunity. These cells contribute to various immune responses like phagocytosis, encapsulation, nodulation, and clotting. The process of melanization, vital for defense against pathogens, is regulated by proteases and involves the activation of prophenoloxidase (PPO). Hemocytes work in conjunction with the fat body, which produces clotting factors and serine proteases, to combat infections. The image also highlights the role of epithelial cells, which produce reactive species as a part of the immune response to microbial threats. 7.2 Unique immune features in earwigs While earwigs share many common immune mechanisms with other insects, they also exhibit unique features. One notable aspect is the potential for immune priming, where prior exposure to a pathogen enhances the immune response upon subsequent encounters. This phenomenon, although observed in other insects, may have unique regulatory mechanisms in earwigs (Cooper and Eleftherianos, 2017; Sheehan et al., 2020). Additionally, earwigs might possess specific antimicrobial peptides or proteins that are tailored to their ecological niches and specific pathogens they encounter, which could differ from those found in other insects (Wojda, 2017). 7.3 Evolutionary adaptation of immune responses The immune responses in earwigs have likely evolved to address specific ecological challenges and pathogen pressures. The ability to mount a rapid and effective immune response, including the production of reactive oxygen and nitrogen species during melanization, is a critical adaptation. The evolutionary conservation of
RkJQdWJsaXNoZXIy MjQ4ODYzNA==