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

Benade, P. C. (2016-03)

Thesis (MSc)--Stellenbosch University, 2016.

Thesis

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 on all continents, except those with extremely low temperatures. In the invaded ranges it can displace native wasp species. This invader was first recorded in the Western Cape Province of South Africa in 2008 with little subsequent attention given to it after this initial record. In 2012 it was recorded in Stellenbosch, some 28 kilometres from where it was first seen. It is now fairly common in the region which prompted investigations into its ecology and effect on native biodiversity. In this study the current invaded range and habitat preferences of P. dominula in the Western Cape of South Africa was determined. It was found to have increased its range into numerous towns within the Western Cape Province. However, P. dominula seemed for the most part to be confined to the Cape Metropolitan area. The Cape Fold Mountain belt to the east and Atlantic 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 thought to be the main driving factor. This because, as demonstrated in this study, P. dominula prefer human altered environments. To successfully invade and persist in a new range, P. dominula may possess a few advantageous characteristics over native species including release from enemies, greater colony productivity, longer activity season and a smaller body size. Here I investigated these factors by comparing P. dominula and the South African native congener species Polistes marginalis where these occur in sympatry. Over a period of 12 months (June 2013 to July 2014) foraging wasp activity of both species was recorded and compared. At the onset of winter and when wasp activity ceased, nests from both species were collected in order to determine 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 abundance than the native species at the onset of P. marginalis activity. Nests of P. dominula also contained more cells than that of P. marginalis denoting greater colony productivity. Body size was not found to be significantly different to that of the native and therefore was not deemed to give P. dominula any advantage. Suprisingly, P. dominula had a greater paratisation rate than that P. marginalis, refuting predictions under the enemy release hypothesis. Polistes dominula is a prolific invader of newly acquired ranges in South Africa. It has already surpassed the natural barrier that once was the Cape Fold Moutain Range and the possibility exists that it could now invade more inland locations towards the east. It also outperforms the native species on several aspects that may lead to an ability to outcompete native congener species. Its effect on native arthropod taxa that forms part of its diet and on plant pollination has yet to be determined, but all evidence suggests that this species should be controlled 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.

AFRIKAANSE OPSOMMING: Die Europese papier perdeby Polistes dominula (Christ) (Hymenoptera: Vespidae: Polistinae) is nou gevestig as 'n effektiewe indringer regoor die wêreld en is aangeteken en bestudeer op alle kontinente, behalwe die met baie lae temperature. In nuutgevonde areas kan inheemse perdeby spesies verdring word deur hierdie indringer. Polistes dominula was vir die eerste keer in die Wes-Kaap Provinsie van Suid-Afrika in 2008 opgemerk. In 2012 was dit aangeteken in Stellenbosch, sowat 28 kilometer van waar dit vir die eerste keer waargeneem is. Dit is nou volop in die streek, wat die studie van hierdie indringer se ekologie en uitwerking op inheemse biodiversiteit belangrik maak. In hierdie studie is die huidige omvang en habitat voorkeure van P. dominula in die Wes- Kaap van Suid-Afrika bepaal. Daar is gevind dat sy verspreidingsarea toegeneem het na verskeie dorpe in die Wes-Kaap. Polistes dominula blyk om grootendeels beperk te wees tot die Kaapse Metropolitaanse gebied. Die Kaapse Vou Bergreeks in die ooste en die Atlantiese Oseaan in die weste skep klaarblyklik hindernisse tot sy verspreiding. Polistes dominula is wel onlangs buite hierdie area gevind en daar word vermoed dat die verspreiding aangehelp is deur die mens. Om 'n suksesvolle indringer te wees en te volhard in 'n nuwe habitat, kan P. dominula beskik oor 'n paar voordelige eienskappe wat nie by inheemse spesies voorkom nie: vyand ontwyking, uiters produktiwe kolonies, ‘n langer aktiewe seisoen en 'n kleiner liggaamsgrootte. Hier ondersoek ek hierdie faktore deur die indringer P. dominula en die Suid-Afrikaanse inheemse Polistes marginalis te vergelyk in areas waar beide spesies saam voorkom. Oor 'n tydperk van 12 maande (Junie 2013 tot Julie 2014) was perdeby getalle tydens hul jag aktiviteite aangeteken en vergelyk. Aan die begin van die winter (toe perdeby aktiwiteit gestaak het) was neste van beide spesies versamel om vyand ontwyking, kolonie produktiwiteit en liggaam grootte te bepaal. Aktiwiteit van die indringer P. dominula is vroeër aangeteken as die van die inheemse P. marginalis wat daartoe gelei het dat daar aansienlik meer aktiewe P. dominula was as die inheemse spesies by die aanvang van P. marginalis aktiwiteit. Neste van P. dominula het ook meer selle as dié van P. marginalis bevat wat 'n aanduiding is van meer effektiewe kolonie produktiwiteit van die indringer. Die indringer het egter nie beduidend verskil van die inheemse spesie in terme van liggaamsgrootte nie en dit was daarom nie oorweeg as ‘n voordeel nie. Polistes dominula was wel meer geparisiteer as die inheemse P. marginalis wat tot gevolg gehad het dat die vyand ontwykings hipotese nie ondersteun word nie. Polistes dominula is 'n produktiewe indringer van nuutverworwe areas in Suid-Afrika. Dit het reeds die natuurlike versperring van die die Kaapse Vou Bergreeks oorgesteek en die moontlikheid bestaan dat dit nou na die binneland in die ooste van Suid Afrika han versprei. Die indringer is ook meer effektief as die inheemse spesie op verskeie vlakke wat kan lei tot die onderdrukking van die inheemse P. marginalis. Die uitwerking van P. dominula op inheemse geleedpotige taksa wat deel van sy dieet uitmaak en die moontlikeid van effekte op plant bestuiwing moet nog bepaal word. Die resultate dui daarop dat hierdie spesie bestuur moet word om negatiewe impak op inheemse biodiversiteit te voorkom. Programme om die impak van P. dominula in Suid Afrika te bestuur moet gefokus word in stedelike gebiede waar dit meerendeels gevind word.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/98524
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