Date of Award

Spring 1-1-2015

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Ecology & Evolutionary Biology

First Advisor

Michael D. Breed

Second Advisor

Rebecca J. Safran

Third Advisor

Samuel M. Flaxman

Fourth Advisor

Carol Wessman

Fifth Advisor

Michelle Sauther

Abstract

A defining characteristic of societies is the ability of their members to perform tasks efficiently. Many proposed mechanisms by which these tasks are performed focus on jobs that can be accomplished by many individuals working independently. However most research neglects those jobs that require coordination among individuals to effectively execute the task. Thermoregulatory fanning behavior in worker honeybees (Apis mellifera L.) requires that coordination. Honeybees respond to increasing environmental temperatures by fanning to circulate the air in their hives and cool the colony down, as temperatures exceeding 36°C causes larval death. The goal of my dissertation is to explore the environmental, social, and physiological mechanisms that regulate this critical response. To explore fanning behavior, I developed an assay where I manipulate the environmental and social contexts to measure behavioral differences. My research shows that honeybees respond more readily to increasing temperatures when they are a part of a group, and are not likely to fan when alone. Additionally, when single honeybees are heated with a larva, they are more likely to fan than honeybees are heated alone. In both of these social contexts, I found that tactile cues are critical for the fanning response to occur; if honeybees are prevented from touching larvae or other adults, they are less likely to fan. I then manipulated the environmental context by altering the rates at which we heated groups of honeybees. I found that honeybees in groups cue in on rate of temperature change by responding faster to more quickly increasing temperatures. Finally, physiologically, I found that octopamine and tyramine play a role in regulating the fanning response. I found that fanners had lower brain concentrations of both octopamine and tyramine, and that honeybees treated with octopamine and tyramine together had a dampened fanning respond. The fanning response is critical for the survival of a colony. Furthermore, fanning is an excellent model system by which to explore the additive effects of individual and group responses to a changing environment. My research elucidates several mechanisms that control the fanning response. My dissertation increases our knowledge about honeybee behavior and expands upon our knowledge of division of labor in social insect societies.

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