Attraction of Varroa jacobsoni, parasite of Apis mellifera by electrical charges

Precise measurement of the electrical charges carried by honey bee workers allows one to investigate the role of this abiotic factor in bee contamination by the ectoparasitic mite Varroa jacobsoni. A metallic cylinder charged with four different intensities (chosen in the range measured on living bees) of either positive or negative sign was used as a lure. The mite's movements in the vicinity of the cylinder was videotaped and subsequently digitized. Spatial and temporal dimensions of the paths were computed by a specially designed analysis programme. The frequency and nature of the contacts with the lure were also noted. A two-way ANOVA indicated no significant differences in the characteristics of the paths between charges of different intensities. However, the charge sign was found to influence the following characteristics: immobility, velocity, turning angle standard deviation and sinuosity. In addition, the frequency with which the mite contacted and climbed on the cylinder was higher in the case of negative charge. We suggest that the mites are not merely passively attracted towards the lure by the action of electrical forces. Rather, the detection of charges triggers a change in the movements of the animal which increases the probability to contact its host.