Masters Degrees (Conservation Ecology and Entomology)
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Browsing Masters Degrees (Conservation Ecology and Entomology) by browse.metadata.advisor "Carvalheiro, Luisa G."
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- ItemEffects of a highly invasive plant (Lantana camara) on an agricultural flower visitation network(Stellenbosch : Stellenbosch University, 2015-04) Nel, Lyndre; Pryke, James S.; Seymour, Colleen L.; Carvalheiro, Luisa G.; Stellenbosch University. Faculty of Agrisciences. Dept. of Conservation Ecology and Entomology.ENGLISH ABSTRACT: Invasive alien plants threaten natural and agricultural pollination systems as they integrate into and disrupt flower visitation networks. Mango (Mangifera indica) production on commercial mango farms in Hoedspruit, South Africa, is an important part of the local economy. Mangoes require pollination for fruiting success, and depend on the native insect community, facilitated by managed bee colonies (Apis mellifera), to pollinate flowers. Managed honeybees and wild insect flower visitors to mango have previously been observed visiting other flowering plants in surrounding natural vegetation, including the alien invasive plant Lantana camara. Lantana camara and mango share similar floral characteristics and co-occur in close proximity, so they may share pollinators/flower visitors. Here, I determined L. camara’s influence on mango flower visitation networks, specifically whether it facilitates visitation, through greater abundance and diversity of insect flower visitors (facilitation), or competes for flower visitors (competition), and whether it supports mango flower visitors when mango trees are not in flower. This study was conducted on the margins of three mango farms and bordering natural vegetation. Firstly, L. camara’s effect on mango flower visitation was investigated by comparing flower visitation to mango in plots with and without L. camara nearby. The presence of L. camara was associated with greater mango flower visitation, with increases in both flower visitor species abundance and richness. Secondly, the composition of flower visitor communities of mango orchard boundaries and bordering natural vegetation were evaluated. Although some flower visitors were shared between mango and naturally occurring plants, flower visitor community assemblages were significantly different between natural vegetation and mango orchard boundaries. In natural vegetation, flies, butterflies, wasps, wild bees and ants played a primary role in the visitation networks, whereas honeybees, wild bees and flies were the main visitors in mango orchards. The presence of L. camara significantly influenced community structure in both natural vegetation and orchards. Natural vegetation with L. camara had a more diverse flower visitor community than natural vegetation without L. camara. Lantana camara seems to facilitate mango flower visitation during mango flowering, attracting a larger visitor abundance and species richness where it occurs in bordering natural vegetation and nearby mango orchard boundaries. However, L. camara was seen to be visited by few species known to visit mango outside of mango flowering, suggesting that L. camara may benefit more from facilitation than mango. Given its extreme invasive nature and threat to local plants which sustain native pollinators, L. camara should be removed from mango orchards and bordering natural vegetation. Furthermore, farm managers are encouraged to plant and maintain indigenous flowering plants, especially plants with a facilitative value to mango, in land surrounding mango orchards to sustain native wild pollinators beneficial to mango pollination.