Neil D. Tsutsui
Assistant Professor, Environmental Science, Policy and Management
University of California – Berkeley, United States

Neil D. Tsutsui is an evolutionary biologist and behavioral ecologist at the University of California-Berkeley. He received his BA from Boston University in Biology (Marine Science) and his PhD in Ecology, Evolution and Behavior from University of California-San Diego. He conducted post-doctoral research at University of California-Davis, and was an Assistant Professor at University of California-Irvine from 2003-2007. Dr. Tsutsui’s research focuses on understanding individual behaviors, forms of social organization, and patterns of evolution. Previous work has applied genetic and biochemical tools to understanding how an introduced ant (the Argentine ant, Linepithema humile) has become ecologically dominant in its introduced range. These ants possess a fascinating social structure, characterized by the formation of geographically massive “supercolonies” in their introduced range. Colonies in the native range (South America) are much smaller and are not ecologically dominant. In recent years, Dr. Tsutsui has been studying how individuals recognize each other as partners or foes. In ants, this process involves various types of learning and memory, as well as the expression and detection of specific chemical odors on each other’s exoskeletons. Future research will focus on applying approaches from genetics, genomics, chemistry and field ecology to understanding how the behaviors of individuals dictate the structure of complex and cooperative social groups.

The Wisdom of the Ant: The Role of Experience in Sociality and Aggression
One form of wisdom is the accumulation of knowledge, often through personal experience, during the course of a lifetime or across multiple generations. Although wisdom is often perceived as a human trait, many other organisms also accumulate knowledge through time, often through real-life experiences, and use this wisdom to modify their future behaviors. This research will focus on how social interactions and experiences among ant workers affect their future behaviors and permit the formation of cohesive, cooperative societies. In Argentine ants (Linepithema humile), there is preliminary evidence that the social experiences of individual ants are crucial for the formation of these insect societies. During two stages of life, in particular, behavioral interactions appear to provide experiences that subsequently define the size and membership of ant colonies as well as the levels of aggressive behavior displayed by individuals. The first of these experiences occurs at the very beginning of an ant’s adult life, as it imprints on the odors of others in the colony, thus forming an internal, neural concept of the types of odors that define colonymates. Then, later in life, adult workers appear to learn from agonistic encounters with other ants, and adaptively alter their future behaviors (sensitization). Three experiments will be performed. Experiment 1 will focus on imprinting by young ants, and will test hypotheses regarding the behavioral consequences of manipulating early social experiences. Experiments 2 and 3 focus on sensitization in adults by providing workers with various stimuli and quantifying the frequency, severity, and specificity of later aggressive behaviors. This research will illuminate how individual experiences can modify future social behaviors. In particular, by selectively presenting colony odor stimuli to individual ants during critical periods of development, these experiments will reveal how first-hand experience is translated into a body of wisdom for future decision-making. These data will provide insights into the rate that experience-based wisdom is accumulated, and may reveal biological limitations or constraints on this process.

Steady progress has been made on the proposed research. In Experiment 1, Tsutsui has conducted fieldwork in northern California, collecting large Argentine ant colony fragments. Several million workers have been collected, along with thousands of queens, males, larvae, and pupae. Replicate laboratory colonies have been constructed and are being maintained in a climate-controlled insectary. The experimental manipulations will begin soon. Experiment 2 is complete, and these data have been analyzed.  A manuscript has been written and submitted to the journal Behavioral Ecology and Sociobiology.  Tsutsui and colleagues have demonstrated that Argentine ants use information from agonistic encounters to inform their future decision-making. Specifically, they have shown that these ants can remember aggressive encounters with other ants, and consequently become more aggressive in future encounters (compared to control ants). Surprisingly, even a single aggressive encounter alters the behavior of ants up to one week later, and probably longer (one week was the maximum time examined).  Fieldwork and laboratory preparations have been completed for Experiment 3 (as described for Experiment 1). Tsutsui and colleagues have acquired some of the synthetic cuticular hydrocarbons necessary for the proposed research, and synthesis of others is nearly complete.

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