EVIDENCE OF AUTOGROOMING AS A MECHANISM OF HONEY-BEE RESISTANCE TO TRACHEAL MITE INFESTATION

Infestations of tracheal mites (Acarapis woodi) were measured in honey bees (Apis mellifera) whose autogrooming ability was compromised by h aving legs or segments of legs amputated. Bees of two stocks, one more resistant (Buck-fast) and one more susceptible to tracheal mite infes tation, were tested by performing amputations on uninfested, young (0- 24 h) adult bees, exposing the treated bees to mites in infested colon ies,then retrieving and dissecting the bees to measure parasitism. In both stocks, bees that had mesothoracic legs amputated had greatly inc reased mite abundances. However,the relative increase in infestation w as greater in resistant bees. Mite infestation increased as more (0 vs . 1 vs. 2) mesothoracic legs were removed. in bees with only one leg r emoved, mite infestations were greater on the treated side, in subsequ ent tests with resistant stock bees only, removing the mesotarsi resul ted in infestations equalling those found when entire mesothoracic leg s were removed, but amputating the four distal mesotarsomeres or the m etatarsi resulted in less significant increases. Restraining rather th an removing mesothoracic legs also resulted in increased infestation. Young (0-24 h) bees were more affected than older (3-4 day) bees by le g removal, indicating that a factor other than autogrooming accounts f or the low susceptibility of older bees to tracheal mites. Together th ese results are evidence that autogrooming is an important mechanism o f protection against tracheal mites, especially in bees known to have genetically-based resistance to the parasite.