Changes in the expression of antimicrobial peptide genes in honey bees (Apis mellifera) under the influence of various pathogens.

Abstract

Honey bees play an invaluable role in the ecosystem as plant pollinators. The dramatic decline in honey bee population has prompted a search for its underlying causes and effective remedy methods. Insects produce antimicrobial peptides (AMPs) which play an important role in the induced humoral immune response. The presence of apidaecin, abaecin, hymenoptaecin and defensin has been confirmed in honey bees. The expression of genes encoding these proteins is activated via two signalling pathways: toll pathway for apidaecins and defensins, and Imd pathway for abaecin and hymenoptaecin. Bee pathogens and parasites affect the expression of AMP genes, thus stimulating or inhibiting immune responses. The main causative agents of the global decline in bee populations include Varroa destructor, deformed wing virus (DWV), neonicotinoids, and microsporidian parasites of the genus Nosema. Researchers are divided over the influence of these pathogens and insecticides on the expression of AMP genes in insects. There is evidence to suggest that the age of honey bee plays an important role, and that peptides should be identified solely in the context of specific age groups. There is also a general scarcity of research into the long-term effects of immunosuppressive factors. The influence of various pathogens on the immune system of bees should be investigated to better understand their mutual relationships and to develop effective bee protection methods.