Phenoloxidase activity and haemolymph cytology in honeybees challenged with a virus suspension (deformed wings virus DWV) or phosphate buffered suspension (PBS)

The innate immune system of honeybees mainly consists in antimicrobial peptides, cellular immunity and melanisation. In order to investigate the immune response of honeybees to immune stressors, three stress degrees were tested. Newly emerged bees naturally DWV-infected were collected from a Varroa mite free apiary and divided into three experimental groups: naturally DWV infected bees. PBS injected bees. and artificially DWV super infected bees. Phenoloxidase activity and haemolymph cellular subtype count were investigated. Phenoloxidase activity was highest (P<0.05) in DWV-superinfected bees. and the haemocyte population differed within the three observed groups. Although. immune responses following DWV infection have still not been completely clarified. this investigation sheds light on the relation between cell immunity and the phenoloxidase activity of DWV naturally infected honeybees exposed to additional stress such as injury and viral superinfection.