An investigation of the relationships between common stressors, brood-signaling, hygienic behavior, and selective breeding in the Honey Bee (Apis mellifera)

Despite the importance of the honey bee (Apis mellifera) to scientific advancement, food security and natural ecosystems, managed honey bee colonies are dying at alarming rates in much of the Northern Hemisphere. Recent declines are largely attributed to anthropogenic stressors and to the spread of natural parasites and diseases, most notably the ectoparasitic mite Varroa (Varroa destructor), which is considered by many to be the most important threat to apiculture today. Varroa resistance programs have been successful and rely primarily on selection for hygienic behavior. However adequate mite resistance through hygienic behavior has not yet been fully achieved, and the signal responsible for triggering the hygienic removal of Varroa-infested brood has remained elusive. Employing behavioral, chemical and molecular analyses, the following dissertation investigates the relationships between honey bee stressors, chemical brood signals, and hygienic behavior for bees originating from three distinct breeding programs. Cross-fostering experiments and chemical analyses suggest that hygienic behavior is influenced by a specific chemical originating from honey bee brood, and that the stressor that triggers this chemical signal is different for brood originating from distinct breeding programs. Additional behavioral and chemical analyses provide evidence of increased iron content and higher rates of hygienic removal of brood from cells overlapping steel wires commonly used by beekeepers to add stability to wax-foundation frames. Improved understanding of the relationships between honey bee stressors, brood signals, and hygienic behavior described in this dissertation has the potential to make a positive impact on the health of honey bees. The broad-scale applicability of results presented here stems primarily from the practicality of the solutions these results imply. Through the development of sustainable strategies to combat the Varroa mite, and by discouraging the use of steel wire stabilizers in wax-foundation frames, this work has the potential to improve honey bee health, and thus positively influence the honey bee’s enormous contribution to the economy and the environment