Submitted to: Apidologie
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 5, 2012
Publication Date: September 3, 2012
Citation: Carroll, M.J., Duehl, A.J. 2012. Collection of volatiles from honey bee larvae and adults enclosed on brood frames. Apidologie. 43: 715-730. doi: 10.1007/s13592-012-0153-x. Interpretive Summary: Many key interactions of bees within the colony and with their natural enemies are influenced by chemicals released by bees. Honey bee larvae signal their needs to adult bees in part by releasing odor volatiles. Both bees and their natural enemies respond to small differences in volatiles. Therefore, there is a need for accurate techniques for collecting and measuring the amount of odor compounds released by bees in their natural environment. We describe a system for collection of odor volatiles from larval and adult bees off enclosed brood comb. The ystem described here captures most of the odors produced by bee larvae and their adult bee caretakers in the natural comb environment. An observation frame made of aluminum and glass was used to completely enclose an entire face of a honey bee frame. Odor compounds were trapped by a filter system and analyzed by gas chromatography chemical analysis. As a test of the system, we measured the amounts of six volatiles released in frames by different age bee larvae and same age adult bees. Releases of adult-associated volatiles remained the same or increased slightly on frames with older larvae. Volatile emissions of odors associated with larvae followed patterns of their use among different age larvae. We recovered more of a food odor compound from comb with young larvae that encounter it than comb containing older larvae. Our system allows for the collection of odors from active bee frames without disturbance of the bees. This volatile collection system can be adapted for the study of the various roles of odor compounds in the honey bee colony.
Technical Abstract: Many key interactions of honey bees are mediated by volatile compounds released by bees or their hive environment. To better understand these interactions, researchers require accurate techniques for the quantification of volatiles from the native comb environment. We describe a system for the in situ collection of volatiles from standard Langstroth frames. The closed volatile collection system detailed here is able to capture the complete odor profile emitted by active brood frames and piece together elements of larval-worker interactions. The system includes an observation frame consisting of a glass plate and an aluminum frame that together enclose a single frame face. When attached to any fully drawn Langstroth deep and embedded in the wax, this frame forms a seal around the edge. A push-pull air flow system and in-line volatile collection filter complete the system, enabling air exchange, environmental control, and volatile capture over the frame face. This system can provide insight into colony chemical communication. As a test, we compared volatile emissions of six compounds from comb containing different aged larvae and their adult bee caretakers. Volatile emissions of four compounds associated with adult bees or colony materials remained constant or increased in comb with older larvae. The alarm pheromone component 2-heptanone was emitted at extremely low levels in trials, suggesting that the enclosed adult workers were calm. By contrast, volatiles associated with larval food production reflected changes in food consumption patterns by larval age. Emissions of the larval primer pheromone E-ß-ocimene was greatest in brood comb containing the young larvae and recently capped brood that produce this terpene. We describe volatile analysis strategies compatible with the observation frame volatile collection system presented here.