Coleopterans as model organisms in insect immunity: a review

As an important order among insects, featuring incredible diversity, Coleopterans are increasingly the subject of immunity research. They are not vectors of human and animal diseases, but their impact on plant communities and plant-based food sources, mainly as pests (forest, agricultural, and storage), is significant. Insect immunity research focuses on the mechanisms required for host defense against a wide array of pathogens. The role of the fat body, hemocytes, the formation of antimicrobial peptides, as well as signaling pathways against infection are essential to insect immunity. Innate immune mechanisms in beetles are closely related to their pathology and the hosts' responses to infectious agents (viruses, bacteria, fungi, microsporidia). Most of the established mechanisms of beetle innate immunity mainly come from model organisms such as Tenebrio molitor, Tribolium castaneum, and Leptinotarsa decemlineata. With the advent of modern and environmentally friendly approaches to pest control, more and more issues related to their reactions to pathogenic infections are becoming key. The current review presents a summary of studied defense mechanisms in Coleoptera and data on insect immunity, established in more than 50 beetle species.