European Paper Wasp (lat. Polistes dominula)

Taxonomy

The European paper wasp was originally described in 1791 by Johann Ludwig Christ as Vespa dominula. The specific epithet dominula is a noun meaning “little mistress”, and following the International Code of Zoological Nomenclature, species epithets which are nouns do not change when a species is placed in a different genus. Authors who were unaware that dominula was a noun have misspelled the species name as “dominulus” for decades. P. dominula is often referred to as the European paper wasp because of its native distribution and its nests, which are constructed from paper and saliva. It is also frequently referred to in older literature as Polistes gallicus, a separate species with which it was often confused.

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 New Zealand, Australia, 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 human-made structures used during international trading between countries.

Life cycle

Overwintering founding queens, or foundresses, spend about a month in the spring constructing a nest and provisioning offspring, the first of which become daughter workers in the growing colony. One or more foundresses begin the colonies in the spring. If multiple foundresses are present, the one that lays the most eggs will be the dominant queen. The remaining foundresses will be subordinate and do work to help the colony. Males are produced later, and when they start to appear, a few daughters may mate and leave their nest to become foundresses the next season. The switch from production of workers to production of future foundresses (gynes) is not utterly abrupt, as has been considered the case for other species of Polistes. Males are often distinguished from female wasps by their curled antennae and lack of a stinger. The colony disperses in the late summer, with only males and future foundresses produced instead of workers, and individuals frequently clustering in groups (called a hibernaculum) to overwinter. Hibernation does not usually take place on former nest sites.

Social hierarchies established within the colony can also influence individual P. dominula’s longevity. Queens live longer than the males or the workers because the workers protect the queens from predators. The queen starts laying eggs in late March or early April, immediately after the “founding phase” of the newly built nest. Then, the colony disperses in the late summer, with only males and future foundresses produced instead of workers. Although individuals frequently cluster in groups (to overwinter), neither most nonreproductive males nor nonreproductive females survive the winter because their lifespans are shorter than a year (around 11 months) and they best survive during warm temperatures. Queens may survive the winter by hibernating.

Relatedness

P. dominula is a social insect that lives in colonies. They are haplodiploid insects, as are other Polistes species. The haploid males produce identical haploid sperm, and diploid females produce haploid eggs through meiosis. In most social insects, colonies are composed of related individuals, and social insects are assumed to help close relatives according to W. D. Hamilton’s theory of kin selection. However, in P. dominula, 35% of the nest mates are unrelated. In many other species, unrelated individuals only help the queen when no other options are present. In this case, subordinates work for unrelated queens even when other options may be present. No other social insect submits to unrelated queens in this way. This seemingly unfavorable behavior parallels some vertebrate systems. This unrelated assistance may be evidence of altruism in P. dominula. The majority of nests had one or more females that were unrelated, especially in the winter before nests are formed and workers born. The nests tend to form from foundresses of different nests from previous years. The foundresses are also found overwintering with other wasp species, showing why unrelated wasps are found during winter. However, after winter when the nests are starting to be formed, an increase in relatedness in the nests is seen, which could result from foundresses searching for more related sisters, instead of unrelated wasps. After winter, as wasps leave their winter areas and return to their nests, an increase in relatedness occurs in the early nest phase. In later stages of the nest, more unrelated wasps are found, which could be because new wasps join established nests.