Histopathological findings of the midgut in European honey bee (Apis Mellifera L.) naturally infected by Nosema spp.

Abstract

Background: Nosemosis is an infection of ventricular epithelial cells of adult European honey bees (Apis mellifera), caused by Nosema species. Until recently, it was thought to be caused only by Nosema apis. Nosema ceranae, originally found in Apis ceranae, has now been recognized also in Europe, and considered a more common infection agent than Nosema apis. This disease is present in bee colonies worldwide and it was recently proposed to be a key factor in colony collapse disorder. As the parasite can be present in honey bee colonies without causing disease symptoms, a sensitive and rapid technique for a proper diagnosis is necessary. Findings: Adult honey samples without signs of disease were collected, observed at stereomicroscopy, necropsied, and then processed for histological examination. The examined organs didn’t reveal any pathology; on the contrary, the histological examination revealed the presence of infected cells all along the ventriculus epithelium. Conclusions: In this paper we demonstrate that histopathology is a sensitive and specific method for the detection of nosemosis and has the additional advantage of being able to provide a diagnosis in colonies without signs of disease. Possible relation with bee colony collapse is also discussed.