Introduction:
Invasive Alien Plants (IAP) pose a serious threat to the natural and economic environment of South Africa. Invasive Alien Plants are plants that are not native to a country and have been introduced either intentionally or unintentionally but are now widespread and abundant in the natural ecosystem. Lantana camara is an alien invasive woody thicket forming shrub, native to tropical South-and Central America. L. camara invasion decreases native biodiversity, degrades land, causes intense fires and toxic to animals which often result in death. Lantana camara spreads by seeds which are dispersed by wind, water and frugivores (i.e. birds, fox and rodents) that feed on L. camara berries. Chemical and mechanical control methods are effective but are labour intensive, expensive and unsustainable. The use of biological control (biocontrol) method to control IAP is receiving much attention in South Africa. Aceria lantanae (Cook) (Eriophyidae) is an L. camara flower gall mite that has been released in South Africa. Aceria lantanae is dispersed by wind and flower-visiting insects. Aceria lantanae breeds inside the flower gall and feeds on it and induces it to develop into microphyllous gall (flower malformation). This will result in a decreased fruit production and stunted vegetative growth, thus reducing the rate of L. camara spread and the formation of dense impenetrable stands.
Aim:
To provide leaners with a basic knowledge of IAP, their impacts and the environmental friendly control method. Furthermore, to create a real world experience for learners, to encourage a sense of connection and a feeling of responsibility to their environment while learning important scientific principles.
Objectives:
- to give them an exposure to IAP biological control;
- to give them a hands on experience on biocontrol agent release and post release evaluation in the field;
- to teach them the basics of using a GPS in the field and projecting the study sites on Tshwane metropolitan municipality map using Arc GIS program.
Methodology:
Learners will be taken to the Agricultural Research Council-Plant Protection Research Institute in Rietondale where they will learn more about IAP and their biocontrol agents. They will also be taken to the University of Pretoria (UP) experimental farm to do an IAP identification exercise. To evaluate the efficacy of A. lantanae on L. camara seed production, two study sites will be selected, one at the UP experimental farm and the other one at the Hub koppie to minimize the chances of biocontrol agent dispersal to the control site by wind and/or flower-visiting insects. Eight 2x2 meters permanent plots will be established within the L. camara infestation. Four plots will have biocontrol agents (treatment) and the other four with no biocontrol agents (control). Before the release of biocontrol agents, all the L. camara inflorescence within the control and the treatment plots will be quantified. A field site monitoring will be done once a month to determine if the agent is establishing, spreading and making a notable impact within the plot.
This will be achieved by
- quantifying the number of damaged inflorescence and taking photos;
- quantifying the number of fruit bearing inflorescence, number of berries per inflorescence and the number of seeds per berry. Then a comparison of fruit production between the control and treatment will be done to measure the efficacy of A. lantanae.
Expected results:
- learners must be able to identify major IAP in South Africa;
- know their impacts in the terrestrial and aquatic ecosystems;
- have a basic knowledge of biocontrol;
- acquire basic skills of field work planning, data collection and analysis, and scientific report writing;
- acquire basic poster design and presentation skills;
- learn that "working together we can do more" strategy yields best results.
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