C. Baso1,2, J. Coetzee2 and B. Ripley1
1Dept. of Botany, Rhodes University, Lucas Ave, Grahamstown, 6139, South Africa
2Dept. of Zoology and Entomology, Rhodes University, African Street, Grahamstown, South Africa
The past two centuries have seen a rapid increase in atmospheric CO2 concentration and this trend is predicted to continue into the future. Studies have shown that plants grown above 600 ppm tend to have increased fitness. This has important implications for the management of invasive alien plants, especially for the field of biological control which is mostly dependent on herbivorous insects. Nevertheless, most of the studies on potential changes in plant-insect interactions under elevated CO2 are based on agricultural systems. However, climate change and invasive species are two of the most prevalent features of global environmental change. Therefore, this warrants active research to help prepare for the future predicted by the IPCC. Thus, the aim of this study was to investigate how elevated CO2 affects the biological control of four invasive aquatic weeds (Pistia statiotes, Salvinia molesta, aquaticum and Azolla filiculoides) that are a threat to natural resources but are currently being successfully controlled by their biological control agents in South Africa. To achieve this, the focal plants were grown at ambient (400 ppm) and elevated (800 ppm) CO2 concentrations with and without their respective biological control agents. The general trend from this study shows that we will continue to enjoy the current levels of control in future climates as the insects were able to reduce plant biomass under elevated CO2 to match those of plants that were grown without herbivory at ambient CO2.
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