Polistes dominulus (Christ) (Hymenoptera: Vespidae: Polistinae) in British Columbia: first collection records of an invasive European paper wasp in Canada

Journal of the Entomological Society of British Columbia, Dec 2004 by Borkent, Christopher J, Cannings, Robert A

Two species of the cosmopolitan genus Polistes (paper wasps), P. fuscatus (Fabricius) and P. aurifer Saussure, are native to British Columbia (Carpenter 1996), although some entomologists consider P. aurifer a subspecies of P. fuscatus (Kenner 2002). These wasps are frequently confused with yellowjacket species (Vespinae) but are easily distinguished by their thread waist, their habit of trailing their legs in flight, and their nests of exposed cells. They frequently nest on manmade structures.

The European paper wasp, P. domimilus (Christ) (Fig. 1), native to Europe, Asia and North Africa, has been introduced into the USA, Australia and Chile (Carpenter 1996). It was first recorded in the USA from Massachusetts in the late 1970s (Eickwort 1978) and its range has since expanded south and west, covering most of the northeastern states (Judd and Carpenter 1996, Pickett and Wenzel 2000, Gamboa et al. 2004, Johnson and Starks 2004). It has also moved north to Kingston (sighted in 2002) and Sandfield (2004), Ontario (H. Goulet, Agriculture and Agri-food Canada, pers. comm.), but apparently no specimens have been collected in eastern Canada. Polistes dominnlus has recently appeared in the western USA from Washington to California and east to Colorado (Landolt and Antonelli 1999, Pickett 2003). It is not clear if these populations are the result of new introductions, possibly from Asia, or of a western expansion of eastern introductions (Johnson and Starks 2004).

In British Columbia, P. dominions was first recorded in late August 2003, when D. Manastryski (3808 Rowland Dr. Victoria, BC) photographed a nest (identified by H. Goulet) in Saanich. No specimens were collected, but the photograph was published on the back cover of the Entomological Society of Canada 2003 meeting program. On 5 September 2004, while walking along the shore of Shuswap Lake in Salmon Arm, the first author found a pre-hibemation cluster of about 25 unusual wasps under an overhang on a wooden signpost. One was collected and identified as P. dominulus. Art Borkent (Royal BC Museum, Victoria, BC) collected 10 wasps from the same cluster on 20 September 2004. There was no nest or nest-building activity; this late-season aggregation behaviour has been previously reported for the species (Landolt and Antonelli 1999).

On 30 September 2004, a P. dominulus nest was collected from a nail protruding from the eaves of a house in Saanich, BC. The nest had three female wasps on its surface (Fig. 1) and 17 between the eaves and the back of the nest. The wasps may have congregated for warmth; the temperature was 7 �C (2130 PDT). The nest held 206 cells, six of which contained larvae in various stages of development. A few other cells were less than a third filled with nectar. This cell number falls well within the range documented for the species by Pickett and Wenzel (2000). None of the specimens collected at either site showed signs of Strepsiptera parasitism. Voucher specimens from both localities are deposited at the Royal BC Museum, Victoria, BC, and the Canadian National Collection of Insects, Ottawa, Ontario.

Polistes dominulus is distinguished from the native P. aurifer and P. fuscatus by the yellow patterns on the thorax (Fig. 2). Polistes dominulus individuals are usually the size of yellowjacket wasps, making them smaller than native species.

Although P. dominulus is clearly expanding its range, the effect of this invasion on native species is not as easily determined (Pickett and Wenzel 2000, Johnson and Starks 2004). The recent appearance of P. dominulus in BC provides an opportunity to measure its effect on native Polistes populations. Probably it will increase in abundance within its new BC range, resulting in many more observations in and around human dwellings, where it prefers to nest.

We thank D. Manastryski, A. Borkent and H. Goulet for their help in collection and discussion of P. dominulus. The manuscript was improved by comments from J. Carpenter and an anonymous reviewer. This study was supported in part by funds from the Royal BC Museum.

REFERENCES

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Judd, T.M. and J.M. Carpenter. 1996. Polistes dominulus (Hymenoptera: Vespidae) found in Michigan. Great Lakes Entomologist 29: 45-46.

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