Horizontal transmission of Wolbachia in the honeybee subspecies Apis mellifera carnica and its ectoparasite Varroa destructor

Recent studies have revealed that the prevalence of Wolbachia in arthropods is attributable not only to its vertical transmission, but also to its horizontal transfer. Horizontal transmission of Wolbachia in the host/parasite community was assessed between the honeybee subspecies Apis mellifera carnica and its ectoparasite Varroa destructor, because Wolbachia has been implicated in reproductive alterations in many insects. We frrst report the vectorial horizontal transmission of Wolbachia in these host/parasite community, detected by diagnostic PCR amplification of the 168 rDNA genes followed by direct sequencing. Identical sequences were found in these host/parasite communities suggesting horizontal transmission of Wolbachia. Interestingly, the infected bees may transmit Wolbachia transovarially making it abundant worldwide.