Northern Paper Wasp (Polistes fuscatus)

Figure 1: Distribution of P. fuscatus. Photo credit: Encyclopedia of Life

Individual/Kin Recognition:

Facial & Abdominal Markings - Individual

Common to the Polistes genus, there are thousands of unique combinations between individuals in facial and abdominal markings; essentially unique, distinguishable individuals in each nest/colony. In an experiment conducted by Elizabeth A. Tibbetts at Cornell University, it was determined that in a sample of 259 individuals from 38 different nests that there were 12 different facial patterns and 4 different abdominal patterns. While these facial markings are indeed unique, in her experiment, Tibbetts manipulated the markings of said individuals to determine if they alone established a hierarchical standpoint within a colony. This was ultimately proven incorrect. However, it was found that the markings established individuality within a colony, with their hierarchical standing accompanying them in the form of their known aggressiveness or submissiveness. Altered wasps who were not recognized were attacked within five minutes of being placed in a random colony, although colonial aggression ceased if the nestmates recognized the familiar cuticular pheromone produced by the individual (Tibbetts 2002).

While the pheromones produced on an individual established it as kin to the colony or a stranger, the varying facial/abdominal markings asserted individuality, and that individuals' place in the colony. Foundresses, the female wasps that construct nests and subsequently colonies, are recognized for their dominance or submissiveness through their unique markings; this aids in knowing which individuals are in fact kin, aiding in colony security/defense, sharing of offspring rearing, and food distribution (Tibbetts 2002).

Pheromones - Kin

As previously mentioned, while facial/abdominal markings identify the individual, colonial wasps can determine kinship through a similarity of pheromones produced on the cuticle of the exoskeleton. Identifying 20 different hydrocarbon-based pheromones produced in total by P. fuscatus, Espelie (et. al.) found three specific pheromones involved in "colony specificity, efficacy in assigning wasps to the appropriate colony, heritability, and lack of differences between foundresses and workers" (Espelie et. al. 1994).

Figure 2: A few of the many faces of P. fuscatus. Credit: Science.

Complementary Adaptation: Enhanced Eyesight

With the adaptation of unique markings that distinguish individuals from one another, greater eyesight is required to be able to ascertain these differences. In contrast to the general assumption among biologists that good eyesight evolved with the need for hunting or survival successes, one wouldn't suspect social interaction would be cause for such adaptation. Dr. Michael Sheehan, author of a study on the visual adaptation and acuity on Polistes wasps found that “larger facets in their compound eyes mean better vision, but we found that as these wasps get smaller, they have larger than expected eyes,” he said. “This demonstrates that they evolved improved acuity relative to size in order to discriminate among different individuals in the colony.” This ability to see in better resolution further aids in socialization between colony inhabitants, as well as enhancing the ability to determine if a wasp is unknown, aiding in colony defense (Sheehan et. al. 2011).

Social Foraging & Queen Determination

Foraging for resources in P. fuscatus is divided between the sexes, serving different roles. All females (workers and queens) forage for nest building materials, which consists of first imbibing from a random water source, followed by seeking dead tree limbs and harvesting wood fibers through masticating with powerful mandibles. The dead wood fibers mix with the water to form a papery substance that is regurgitated and used to form a nest. Water is a vital substance for the overall well-being of the colony, and is collected by both sexes (West-Eberhard 1969). Males actively forage for carbohydrates and proteins, usually from plant sources and dead arthropods, respectively. These foraged foods are largely distributed to the brood for consumption, softened up by the males and regurgitated with water to feed larvae, or deposited to the side as a food store (Hunt et. al. 1979).