Thomas Seeley, Ph. D - US grants

Interactions within animal societies are a complex mix of cooperation and conflict. This study will examine how the individuals in the honey-bee colony, a society exhibiting an extreme degree of cooperation, are nonetheless in conflict during certain of the colony's activities. The study focuses on the point of greatest conflict in honey-bee social life: the division of the colony between queens during swarming. It is among the first in hundreds of years of observations on bees to describe the behaviors of individual bees during swarming and afterswarming. Of special interest in this study is an understanding of how the bees decide which queens leave with swarms and how many swarms (queens) are produced, and how these decisions, resulting large-scale, colony-wide events, are built up from the behavior of individuals. This research will contribute to the general theory of social behavior by testing predictions of current evolutionary theory within a colony of advanced social insects. It will add to understanding of the way in which evolution shapes animal communication, and it will broaden our view of the nature of the societies of the advanced social insects by showing how, because they are genetically distinct, individuals within these societies may sharply conflict, although they so often cooperate. In addition, the control of swarming in honey bees remains one of the unsolved problems in practical management of honey bees for honey production and pollination of food crops. This research into the surprisingly little-studied social biology of swarming may thus have practical implications for the beekeeping industry and agriculture.

This research project will strengthen our understanding of how the members of a honey-bee colony work together to efficiently gather their food. The flowers that provide the nectar and pollen generally occur in patches, and the different flower patches vary in their profitability to the bees depending on such factors as distance from the hive, abundance of nectar or pollen, sugar concentration of the nectar, and so forth. If the colony is to gather its food efficiently, it must solve the problem of allocating its foragers among the different flower patches in accordance with their different degrees of profitability. Dr. Seeley's prior work has shown that the colony's decision- making is highly decentralized. Indeed, it seems that it is distributed among all of the foragers in the colony rather than in some supervisory subset of the colony. The present investigations will elucidate several still-unknown aspects of this group decision-making process, such as exactly how the recruitment to different food sources is regulated in relation to the profitability of each food source. This research will also examine more deeply how a colony adjusts its choosiness among nectar sources in relation to its nutritional status. Dr. Seeley will investigate how a colony keeps the ratio of forager bees and food-storer bees in balance so that the difficulty of finding a food-storer bee serves as a reliable indicator of the colony's nutritional status. The general significance of this research has several dimensions. First, for basic biology, it provides a unique view of the high level of functional organization that has evolved in animal societies, and it reveals some of the elegant devices produced by natural selection that enable these societies to function as coherent units. Second, it shows how natural selection has built animal groups capable of performing distributed information- processing to solve problems. Hence it is demonstrating that animal societies, not just the nervous systems of organisms, offer lessons in how to build intelligence. And third, it has practical implications in that it greatly strengthens our understanding of how honey-bee colonies in agricultural settings choose to accept or reject a given crop as a food source and hence function well or poorly in pollination.

Colonies of advanced social insects consist of thousands of separate individuals each acting independently, yet the colony as a whole functions as a coherent unit. This is clearly seen in such collective activities as group food-gathering, colony thermoregulation, nest construction, and colony defense. The subunits of the colony, the individual workers, are somehow coordinated into a well-organized functional unit, but the integrative mechanisms remain largely a mystery. Scott Camazine's doctoral dissertation will focus on one example of a precisely organized colony-level process: the collection of the honey bees' protein food, pollen. The goal of the research is to understand how the collection of pollen is regulated. The approach will be to identify which castes of bees are involved in the pollen-foraging process, and to identify the flow of information among these bees concerning the colony's need for pollen. These results will elucidate how the regulation of a colony's foraging emerges from the collective behaviors and interactions of its constituent members. This research will both suggest how honey bees' pollen collection could be manipulated to enhance their value as pollinators of food and seed crops, and strengthen our understanding of how biological subunits--be they molecules, cells, or organisms--are tightly integrated into functionally organized wholes.

Behavioral analysis of a group decision-making process
Thomas D. Seeley
One of the most spectacular examples of an animal group functioning as a collective decision-making agent is a swarm of honeybees choosing its future home. This phenomenon occurs in the late spring and early summer when a colony outgrows its hive and proceeds to divide itself by swarming. The swarm bees leave en masse, quickly forming a cloud of bees just outside the parental hive; they then coalesce into a beard-like cluster on a nearby tree branch where they choose their future dwelling place. The nest-site selection process starts with several hundred scout bees flying from the swarm cluster to search for tree cavities that meet the bees' real-estate preferences. The scouts then return to the cluster, report their findings by means of waggle dances, and work together to decide which one of the dozen or more possible nest sites that they have discovered should be the swarm's new home.
The PI will determine (1) how the scouts in a honey bee swarm work together to make the decision regarding their future nest site, and (2) how they sense when they have finished making this decision. Such group decision making, or social choice, occurs in many species of group-living animals. Unraveling the mechanisms of social choice is essential to understanding how animal groups function and may even lead to novel methods of social choice by humans. A swarm of honey bees choosing its nest site is a striking and accessible form of social choice by animals.

One of the goals of behavioral biologists is to understand why sometimes there is close cooperation among in animal societies and why at other times there is intense conflict. This project will help us understand the shifting balance between cooperation and conflict by investigating a striking switch from strong cooperation to stunning conflict inside the nests of a common species of yellow jacket wasp called Dolichovespula arenaria. The nests of these wasps are the familiar grey, paper structures about the size of a soccer ball that appear in trees and on buildings. Inside each one lives a family of wasps that includes a mother wasp (the queen) and dozens of her daughters and sons. Most of the time, the daughter wasps cooperate with their mother, helping her by building the nest, defending it, collecting food, and helping rear the queen's offspring. But late in the summer, one of the daughter wasps will suddenly sting and kill the mother wasp and then start laying eggs herself. How such a dramatic switch from cooperation to conflict can have evolved is the puzzle that this study addresses. Using novel video recording methods that enable us to carefully monitor the situation inside each colony at the time of the matricide, the PI will test several hypotheses for how it can actually benefit a daughter wasp to kill her mother. One possibility is that the mother wasp has lost her fertility, in which case the workers have little to lose and much to gain by killing their mother and taking over the nest. This work will be deepen our understanding of the biological forces that influence cooperation and conflict, and this is a matter of great relevance to human society.

Honey bees, live as a group of organisms that form a cooperative unit: a colony. Colonies, like individuals, have a cycle of growth and development. When a colony transitions between developmental stages, the workers must coordinate the transition. The goal of this project is to understand the cues that non-reproductive worker honey bees use to detect the developmental stage of their colony and coordinate the switch between producing more workers and producing reproductive males and females (drones and queens). This research will encourage collaboration between researchers studying animal behavior, chemical ecology, and electrical engineering. Current methods used by beekeepers to assess the strength and developmental stage of a honey bee colony are based on metrics that humans can easily determine, but are almost certainly not those used by the bees. Honey bees are the primary pollinator of agricultural crops worldwide, providing billions of dollars of pollination services. By identifying the metrics that bees use to detect their own colony's development, this research will help beekeepers determine which colonies need to be managed, and when. Better colony management can in turn improve crop production. The outcomes of this research will be shared through beekeeping classes. This project will also train graduate and undergraduate researchers in behavioral ecology, chemical ecology and engineering.

Descriptive work has shown that social insect colonies invest first in workers (for growth) and then switch to producing reproductive individuals. Theoretical work has shown why colonies invest as they do, but it is unknown how developmental transitions are coordinated. The researchers recently discovered that a threshold number of workers is the trigger that induces honey bee colonies to invest in reproduction, but how workers detect this reproductive threshold is unknown. The goal of this research is to test two hypotheses of the mechanism by which individual honey bees assess their colony?s size: (1) beeswax comb vibrations, and (2) volatile chemical compounds. Using accelerometers to measure comb vibrations, and gas chromatography to analyze chemical compounds, the researchers will determine whether these cues reliably change with colony size. The cues will then be experimentally manipulated, to determine which one(s) the workers use to detect that their colony is above the reproductive threshold. Understanding the cues that superorganisms use to coordinate their developmental transitions will give insights into how evolution has solved similar problems at different levels of biological organization such as individuals and societies.