Grooming behavior by worker bees of various subspecies of honey bees to remove Varroa destructor mites

Abstract

Grooming behavior by honey bees is regarded as an important trait that contributes to the defense against the parasitic mite Varroa destructor. We carried out an assay to investigate how effective autogrooming by honey bees is in removing V. destructor mites. We compared the behavior of the Carniolan bee (Apis mellifera carnica), represented by two lines: Kortówka and Dobra; the Caucasian bee (Apis mellifera caucasica) of the Woźnica line; the black bee (Apis mellifera mellifera) of the Augustowska line; and the crossbreed of two subspecies: Apis mellifera capensis × A. m. carnica. We found that most worker bees do not tolerate the mite on their bodies. The most intense reaction, manifested by strong motor activity, was observed in A. m. mellifera worker bees; as many as 98% of worker bees in this group made an attempt to remove mites. In the remaining groups, a response was observed in 86% for Caucasian bees to 89.3% for Carniolan bees, Dobra line. The attempts made by bees of different origins to remove mites differed in effectiveness, duration, and frequency. The highest percentage of removed parasites was noted in Caucasian bees (11%), and the lowest in Carniolan bees of the Kortówka line (1.5%). A. m. mellifera devoted the most time to the reaction to varroa on their body, i.e., an average of 64.7 s of 180 s of the experiment. In most trials, worker bees manifested at least three defensive reactions, and the highest number of such trials was observed in the black bee (117). We did not observe allogrooming in all bee groups or types. The results indicate that A. m. mellifera shows the strongest grooming behavior of all bees used in the experiment.