COMPARISON OF DIAGNOSTIC METHODS FOR DETECTION OF LOW INFESTATION LEVELS OF VARROA-JACOBSONI IN HONEYBEE (APIS-MELLIFERA) COLONIES

Thirty-five honey-bee colonies, originally free from Varroa jacobsoni (Oudemans) were monitored approximately every third week for the presence of the mite during 16 months following an initial introduction of five to eight adult Varroa females in early July. Investigations of hive debris detected the presence of V. jacobsoni in 22 colonies (63%) within three months of the mite introduction. During the first winter period (October-April), mites were found in the hive debris of 13 colonies (37%). In terms of detecting Varroa during the summer in colonies with sealed brood, investigations of hive debris were more effective than sampling of brood. Brood sampling was more effective than sampling of live bees. In colonies without sealed brood, investigations of hive debris or of live bee samples seemed approximately equally efficient. The highest correlation between sampling methods was found between daily mite downfall and mites per live bee (r = 0.81) in colonies with sealed brood. During the winter, investigations of dead bees and hive debris were approximately equally efficient in detecting Varroa.