Nosema ceranae DNA IN HONEY BEE HAEMOLYMPH AND HONEY BEE MITE Varroa destructor

Honey bee mite Varroa destructor and microsporidium Nosema ceranae are currently considered the most important threats to honey bees and beekeeping. It has been believed that both N. apis and N. ceranae invade exclusively epithelial cells of the honey bee ventriculus. However, some findings suggest that these microsporidia may infect other tissues of honey bees. There are indications that these pathogens could be found in honey bee haemolymph, as the medium for its distribution to anatomically distant tissues. Knowing that V. destructor being an ectoparasitic mite feeds on the honey bee's haemolymph, the aim of this study was to investigate if DNA of Nosema spp. microsporidia could be found in honey bee haemolymph and in V. destructor. The study was conducted on bee haemolymph and V. destructor mites from 44 Apis mellifera colonies. From each hive five mite individuals and 10 mu L of haemolymph (from 4-5 bees) were used as samples for DNA isolation and PCR detection of Nosema spp. The DNA of N. ceranae was confirmed in 61.36% of V. destructor mites and 68.18% of haemolymph samples. This is the first report of N. ceranae DNA in honey bee haemolymph and in V. destructor mites. The finding of DNA of N. ceranae in V. destructor could be interpreted as the result of mite feeding on N. ceranae infected bee haemolymph. However, for a full confirmation of the vector role of V. destructor in spreading of nosemosis, further microscopy investigations are required for the detection of spores in both investigated matrices (haemolymph and V. destructor internal tissues).