Patterns of labor organization in the eusocial wasp, Vespula germanica (Hymenoptera: Vespidae).

摘要

Vespula germanica is a eusocial wasp whose colony grows from a founding queen to several thousand workers. Without direction from a central organizer, individuals decide to perform different tasks, such as nest construction, brood care, foraging, and defense.; This dissertation describes a weak temporal division of labor of workers among tasks. Nest tasks typically preceded foraging, and pulp foraging often preceded food foraging. Individuals' task sequence and age of first task performance varied greatly. The daily labor force was split between specialists and generalists. Carbohydrate foragers made significantly more carbohydrate trips on days they performed other kinds of tasks. Thus, the rate of task performance was not coupled with task specialization. Workers used task partitioning for food but not pulp. Using network theory, I describe the efficiency benefits of this distribution pattern. I compare the life histories of V. germanica , honey bees, and Polybia occidentalis wasps to explain why a generalist pattern of labor division benefits large colony vespines.; I describe the allocation of labor within the task of carbohydrate foraging. The distribution of the number of trips, y, over the number of foragers, x, is highly skewed to the left. A similar distribution has been seen in other social insect species performing other kinds of tasks. The few workers performing a disproportionate amount of the work have been called 'elites'. My study was the first to operationally define the 'elite' group. However, I show that a straight line on a log-log plot fits the distribution well, thus it follows a power law. I describe how my data both support and conflict with an interpretation of carbohydrate-foraging labor as a self-organized system.; To investigate the cause of the distribution, I tested the effects of forager age, experience, temperature, body size, ovarian condition, and natal colony on carbohydrate-foraging behavior. While these factors were significant for some observation periods, they explained a very small part of the variation. Analysis of the residual error showed that as yet unidentified individual differences among wasps play an important role. I suggest that randomness and worker-worker interactions interact with physiological factors to produce the skewed distribution.