Invaded range and competitive ability of the newly invasive Polistes dominula compared to that of its native congener species in the Western Cape, South Africa

[摘要] ENGLISH ABSTRACT: The European paper wasp Polistes dominula (Christ)(Hymenoptera: Vespidae: Polistinae)established itself as a prolific invader across the globe and has been recorded and studied onall continents, except those with extremely low temperatures. In the invaded ranges it candisplace native wasp species. This invader was first recorded in the Western Cape Province ofSouth Africa in 2008 with little subsequent attention given to it after this initial record. In2012 it was recorded in Stellenbosch, some 28 kilometres from where it was first seen. It isnow fairly common in the region which prompted investigations into its ecology and effect onnative biodiversity.In this study the current invaded range and habitat preferences of P. dominula in the WesternCape of South Africa was determined. It was found to have increased its range into numeroustowns within the Western Cape Province. However, P. dominula seemed for the most part tobe confined to the Cape Metropolitan area. The Cape Fold Mountain belt to the east andAtlantic Ocean to the west apparently creating a hinderance to its dispersal. Even so, P.dominula was later also found outside of this area with human mediated distribution thoughtto be the main driving factor. This because, as demonstrated in this study, P. dominula preferhuman altered environments.To successfully invade and persist in a new range, P. dominula may possess a fewadvantageous characteristics over native species including release from enemies, greatercolony productivity, longer activity season and a smaller body size. Here I investigated thesefactors by comparing P. dominula and the South African native congener species Polistesmarginalis where these occur in sympatry. Over a period of 12 months (June 2013 to July2014) foraging wasp activity of both species was recorded and compared. At the onset ofwinter and when wasp activity ceased, nests from both species were collected in order todetermine enemy release, colony productivity and body size. Activity of the invasive P.dominula started earlier than the native P. marginalis allowing it to have greater abundancethan the native species at the onset of P. marginalis activity. Nests of P. dominula alsocontained more cells than that of P. marginalis denoting greater colony productivity. Bodysize was not found to be significantly different to that of the native and therefore was notdeemed to give P. dominula any advantage. Suprisingly, P. dominula had a greaterparatisation rate than that P. marginalis, refuting predictions under the enemy releasehypothesis.Polistes dominula is a prolific invader of newly acquired ranges in South Africa. It hasalready surpassed the natural barrier that once was the Cape Fold Moutain Range and thepossibility exists that it could now invade more inland locations towards the east. It alsooutperforms the native species on several aspects that may lead to an ability to outcompetenative congener species. Its effect on native arthropod taxa that forms part of its diet and onplant pollination has yet to be determined, but all evidence suggests that this species should becontrolled as much as possible in order to prevent negative impacts on native biodiversity.These programmes should be focussed in urban areas where these wasps proliferate.

[发布机构] Stellenbosch University