Varying congruence of hygienic responses to Varroa destructor and freeze-killed brood among different types of honeybees

Abstract

Honeybees, Apis mellifera, selected for the hygienic removal of freeze-killed brood (FKB), resist several microbial diseases and have some resistance to Varroa destructor. Bees with Varroa-sensitive hygiene (VSH) have good resistance to V. destructor. We determined whether the response to FKB could be used to select for VSH by measuring the responses of different bees (VSH, FKB-selected, F1 VSH, and unselected control) to combs with FKB and combs with mite-infested brood. All bee types completely removed much FKB (77–88 %) within 24 h. The removal of mite-infested brood after 1 week was much more variable among bee types (VSH, 66 %; F1 VSH, 51 %; FKB hygienic, 14 %; control, 3 %). There was some relationship between 24-h manipulation of FKB cells (i.e., cell contents at least partially removed) and the removal of mite-infested brood, but this appears to have little practical relevance because of a large inherent variation.