Description
Polistes dominula is aposematically coloured (black & yellow), unlike other native Polistes species, and look very similar to the infamous aggressive wasp Vespula germanica. One can easily distinguish them by the colour of their antennae. The lesser degree of predation experienced by Polistes dominula often attributed to this aposematic coloration
Distribution
The native range of Polistes dominula comprises predominantly of Mediterranean climates, including Europe, Asia and northern Africa. It was first recorded in North America during the late 1970s from where it rapidly spread southwards replacing native species within a few years. It is considered a highly invasive species especially in South Africa as it is not confined to Mediterranean climatic zones.
The first published observation of its presence in South Africa was made in the Western Cape Province in 2008 in the suburb of Kuilsriver. Its presence has now also been confirmed in Stellenbosch, Somerset West, Jonkershoek and Paarl
Behaviour & Life History
Polistes and Vespula species are however analogous in terms of their occurrence in temperate areas, formation of annual colonies and that future queens (foundresses) undergo diapause. Evidence do however suggest that Polistes dominula can be multi-seasonal and not undergo diapause.
Nest are established through the process of haplometrosis whereby a nest is founded by one or more fertilized, egg laying foundress (s). (Fig. 4)
Nests are constructed anew each year, but philopatry can occur. The foundress deposits one egg to a cell that hatch in several days. Larva are fed soft bodied insects until mature and emerge as worker females (ca. 40 days) taking over duties of food collection, nest construction and defence (Fig. 3).
Polistinae nests are aerial and commonly attached to manmade structures and in some cases plants, in contrast to other Vespidae nests mostly found below ground. Nest placement explaining why Polistes dominula is much more abundant in urban than natural areas.
Impact, Risks and Concerns
Invasive Polistes dominula compete directly with our native species (eg. Polistes fastidiousus and P. marginalis) for food and shelter to the extent of reducing the numbers of natives and disrupting natural processes and arthropod numbers.
