Читать книгу Honey Bee Medicine for the Veterinary Practitioner - Группа авторов - Страница 75

Social, compared with solitary organisms, are at an increased risk of disease because often, as with the honey bee colony, large numbers of individuals are living in a confined nest with stored resources; however, group living also imparts heightened infection control measures (Evans et al. 2006; Fefferman et al. 2007; Kurze et al. 2016). The social structure of the hive helps defend against disease in many ways (e.g. grooming, hygienic, and necrophoric behaviors, use of propolis with anti‐microbial properties, social fever in response to disease, as well as nest hygiene and defense among others) (Evans et al. 2006; Vidal‐Naquet 2015).

Individual bees also have physical properties that help prevent infection in addition to both cellular and humoral immunity for the recognition and removal of pathogens. Several morphologic characteristics of insects help combat infection (Evans et al. 2006). A layer of antimicrobial secretions covers the external surfaces of many types of insects and the intestinal tract with digestive enzymes is not friendly to pathogen survival, although the semipermeable midgut is documented as entrance site for several honey bee pathogens (Davidson 1973). In addition, the gastrointestinal tract of the adult worker honey bee is characterized by a core set of bacteria that are not only important in nutrition and metabolism, but also protective against pathogen infection (Raymann and Moran 2018). Next, the exoskeleton cuticle of the honey bee forms a physical barrier against pathogen invasion, as does the peritrophic membrane of the intestinal tract (Vidal‐Naquet 2015; DeGrandi‐Hoffman and Chen 2015). Further penetration of the honey bee by an infectious agent elicits an immune response at the level of the hemolymph and fat body. Such immune defenses of insects are similar to the innate immune system of vertebrates, both sharing many characteristics including the actions of phagocytosis, secretion of antimicrobial peptides, enzymatic degradation of pathogens, as well as similar architecture and orthologous components (Evans et al. 2006). Unlike vertebrates however, insects lack adaptive immunity and cannot produce antibodies; rather the honey bee immune response is characterized by non‐specific reactions against pathogens via both cellular and humoral immunity (Vidal‐Naquet 2015; DeGrandi‐Hoffman and Chen 2015). Specifically, the binding of highly conserved structural motifs of pathogens by special receptors activate hemocyte‐mediated cellular events such as phagocytosis or encapsulation of the pathogen, induction of hemolymph coagulation or melanization, or the synthesis of antimicrobial peptides (DeGrandi‐Hoffman and Chen 2015). Further, RNA interference, a major antiviral immune response of insects, has also been identified in several honey bee studies (DeGrandi‐Hoffman and Chen 2015).