Grooming behavior and damaged mites (Varroa jacobsoni) in Apis cerana cerana and Apis mellifera ligustica

Varroa mite mortality and mite damage in colonies of Apis cerana cerana Fabr and Apis mellifera ligustica Spin, where mites were added to observation hive bees and to full-sized colonies of both bee species, were studied. The results show grooming behavior in A cerana but the results also indicate that this behavior may be less effective than previously recorded. In A mellifera colonies, phoretic mites were also removed by the bees but less effectively than in A cerana colonies. The proportion of experimentally-added live mites in the debris that were visibly damaged in colonies of A cerana was 30% (n = 115). From A mellifera colonies, 12.5% of the introduced mites had visible injuries caused by the bees (n = 65). The mites recovered from both bee species showed reduced survival rate on bee pupae compared to control mites. Compared to A mellifera, A cerana is more effective in both removing mites and causing mite damage. However, in A mellifera phoretic mites are also removed by the bees, and some of them are injured. Since no reproduction of Varroa mites occurs in worker brood in A cerana, extremely effective grooming behavior may not be needed to explain the tolerance of A cerana to Varroa mite infestations. The results presented demonstrate that more research is needed to evaluate the importance of grooming behavior to Varroa mite tolerance in both A cerana and A mellifera.