European paper wasp

Appearance

Little variation occurs among individuals of "P. dominula"; the wing lengths of males range from 9.5 to 13.0 mm, while those of females range from 8.5 to 12.0 mm. Its body is colored entirely yellow and black, similar to that of "Vespula germanica", one of the most common and aggressive wasps in its native range. The female mandible is black and sometimes has a yellow spot. Females have a black subantennal mark that rarely has a pair of small, yellow spots. The female vertex sometimes has a pair of small, yellow spots behind the hind ocelli. Females have yellow, comma-shaped scutal spots.

Naming

Before 1995, "P. fuscatus" was the only species of "Polistes" in Michigan. In the spring of 1995, one single foundress colony of "P. dominula" was discovered nesting in the "Polistes" nestbox at the Oakland University Preserve in Rochester, Michigan. In 2002, about one-third of the "P. dominula" colonies at the preserve were removed because of the concern about losing the resident population of "P. fuscatus". Although the removal of "P. dominula" population did slow down their expansion, in 2005, 62% of the colonies at the Preserve were "P. dominula". A number of researchers concluded that "P. dominula" was likely replacing "P. fuscatus" through indirect or exploitative competition, which was consistent with their finding that "P. dominula" was significantly more productive than "P. fuscatus".

Distribution

The native range of "P. dominula" covers much of southern Europe and North Africa, and temperate parts of Asia as far east as China. It has also been introduced to Australia, New Zealand, South Africa, and North and South America. Since the mid-1980s, the population of "P. dominula" has expanded to rather cooler regions, especially towards northern Europe. Global warming is speculated to have raised temperatures of certain areas, allowing "P. dominula" to expand to originally cooler regions.

The first North American occurrence of "P. dominula" was reported in Massachusetts in the late 1970s, and by 1995, this species had been documented throughout the northeastern USA. However, the species is also likely present in additional states, but has just not yet been reported. Although detailed mechanisms of the species' dispersal are still unknown, some number of individuals, including the foundresses, may have hidden inside transportable items such as shipping crates, trailers, boats, or other man-made structures used during international trading between countries.

Status

Black facial patterns are associated with the male "P. dominula" dominance and conditions. Facial patterns of the male "P. dominula" vary from being “unbroken” to “scattered” - unbroken black spot represents “low quality” while scattered spots represent “high quality”. Males generally avoid fighting with “high quality” males and fight for resources that “low quality” males are protecting to reduce the cost of aggressive competition. Naturally, such behaviors give rise to social hierarchy, placing males with more spots on top of the social class.

Similar to the abdominal spots that imply strong fighting fitness and mating success in male "P. dominula", the salient patterns on the female's clypeus demonstrate strong correlation to its dominance and is used to facilitate rival assessments.

Behavior

Abdomen rubbing of the female "P. dominula" occurs during the egg stage of the colonies, more in multiple-female colonies than in solitary colonies. Several functions of female abdominal rubbing are possible, one of them being painting predator-resistant chemicals on the surface of the nest for defense. A second possible function is to communicate the dominance status of the female to the young brood. Alpha females perform abdomen stroking more than subordinate females. After an alpha female is removed, subordinates increase their abdomen stroking rate. The substances secreted during the rubbing have two potential functions - repressing future ovarian development In the brood or informing the brood of which adult female is the dominant individual.In the first 12 days of the nesting period, 75% of foundresses leave their original nests, and travel to around three nests before settling permanently, choosing the nest with the highest reproductive payoff. Foundresses choose nest sites by weighing the benefit of an expanded colony with the cost of predation risk. Multiple-foundress nests have a higher chance of survival compared to single-foundress nests, and in general, foundresses found nests with those with which they hibernate in the same aggregation.

Habitat

"P. dominula" generally lives in temperate, terrestrial habitats such as chaparral, forest, and grassland biomes. They also have the propensity to colonize nearby human civilizations because man-made structures can act as great shelters and also are located close to the resources such as food.

Reproduction

Because the chemicals coated on the nests are equivalent to that present in adult "P. dominula" bodies, young wasps learn this chemical template in the very early state of the adult life to later on be able to distinguish their nest mates from non-nest mates. The CHC composition of the larvae and adults are very different, in that the larvae's relative abundance of low-molecular-weight CHCs is higher and that the larval profiles are more uniform than those of adults. Adults are also able to distinguish odors of their own colonial larval CHCs from those of foreign colonys.

Food

"P. dominula" has a more generalist diet than many other "Polistes" species, giving it a more flexible selection of prey. One study in Europe found that the prey items brought back to nests by "P. dominula" colonies represented three insect orders while in contrast, North American "Polistes" primarily only use caterpillars to feed their offsprings. Some other theories, however, suggested not that individuals have a more general dietary, but rather the response of colonies may be more opportunistic relative to resources. For example, "P. dominula" uses more workers to increase the amount of foraging, use eggs to feed the offspring, and reduce allocation of protein to nest construction to take advantage of poorer quality prey during periods of low prey availability.

Defense

Another strength of "P. dominula" in terms of survivorship is their ability to suffer less nest predation than other "Polistes". "P. dominula" is a less attractive prey for birds mainly due to its aposematic coloration and he relatively strong attachment of the comb to the substrate – typically tree branches or man-made structures. Unlike "P. fuscatus", which is colored brown with a few faint, thin, yellow stripes, "P. dominula" is colored bright yellow with alternating black, similar to the warning coloration of "Vespula germanica", a common and aggressive yellowjacket. In addition to their alerting coloration, "P. dominula" comb strength also contributes to their higher chance of survivorship. "P. dominula" might have an advantage over "P. fuscatus" against avian predators because their combs are less likely to be dislodged from the substrate by birds because the side force required to dislodge it is greater for "P. dominula" than for "P. fuscatus" combs.