Chemical Communication and Improved Tools for Hygienic Selection in the Honey Bee, Apis mellifera
Kaira Wagoner, Kaira Wagoner , Coby Schal , Jocelyn Millar , Marla Spivak , Olav Rueppell
Biology Department, University of North Carolina at Greensboro, USA; University of North Carolina at Greensboro, USA ; North Carolina State University, USA ; University of California Riverside, USA ; University of Minnesota, USA ; University of North Carolina at Greensboro, USA
The health of the honey bee Apis mellifera is currently being challenged by several natural and anthropogenic threats. Among these are the ectoparasitic mite Varroa destructor, and the numerous harmful pathogens it vectors to its honey bee host. While many Varroa control methods have been developed, constraints such as limited uptake and the evolution of resistance to chemical interventions have resulted in little progress, such that Varroa remain a critical threat to honey bee health today. One promising avenue for improved intervention is the breeding of hygienic honey bees, capable of detecting and removing brood that is parasitized or otherwise unhealthy. In an effort to improve hygienic selection methods and expand our understanding of the role of brood in hygienic behavior, we investigated honey bee cuticular chemicals associated with unhealthy brood. We identified multiple hydrocarbons with the same basic structure that are elevated in unhealthy brood, as well as in brood targeted for hygienic removal. Using a synthetic-chemical assay we demonstrated that hydrocarbons with this general structure could be applied to wax caps to induce hygienic removal. We then found a significant positive correlation between hygienic response to our assay and the traditional liquid nitrogen-killed brood assay. These findings expand our understanding of honey bee chemical communication and suggest that a chemical assay based on natural honey bee brood chemicals may serve as a suitable and potentially improved indicator of colony hygiene level. This work will likely lead to the development of improved tools for colony monitoring and hygienic selection, and thus to improved resistance of honey bees to Varroa and associated pathogens. Furthermore, these findings may provide important insights into the intracolonial communication of other social insect species.