Response of the Apoidea to Fungal Infections

The survival of the bee depends on the successful defense against microbial invaders, parasites and predators. The honey bee immune system, like other species of holometabolous insects, depends on two main categories of defense reactions: the cellmediated responses such as phagocytosis and encapsulation of foreign objects and cell-free defense mechanisms represented by the antimicrobial immune proteins. Phagocytosis and encapsulation are the most common mechanisms in bees against entomopathogenic fungi. The hygienic behaviour, antimicrobial secretions of worker bees and protective barriers of the body coverings forming the effective thresholds and protecting the bee haemocoel against fungal invasions are supported by the haemocyte-mediated immune responses in defense against mycotic infections. The protection of the bee colony to fungi is realized by hygienic behaviour and secretions but individuals are protected by body coverings and cellular immune reactions. Neither the lysozyme nor the inducible immune proteins of the bee act against fungal invaders. The antifungal immune peptides such as drosomycin in the fruitfly (Drosophila melanogaster), thanatin in the bug (Podissus maculiventris), mietchnikowins and metalnikowins that exhibit activity against both bacteria and fungi, have not been detected in the naive and infected honey bees.