Prof. Julie Coetzee

Aquatic Weeds Programme Manager


PhD, University of the Witwatersrand (2003)

Julie completed her PhD at the University of the Witswatersrand in 2003. Currently her research focuses on the biological control of invasive aquatic plants. She started working on biological control agents of water hyacinth in 1998, and has never looked back. Recently she has shifted the focus of her work on floating aquatic plants to submerged and emergent aquatic plants. As we have gained excellent control of the floating species, this new suite of species has taken advantage of these new habitats, threatening indigenous aquatic flora and fauna. Tackling these new problem plants is a challenge, but we will benefit from experience gained elsewhere in controlling these species, as well as pioneering new methods of control for South Africa.

Research Interests
  • Biological control of weeds
  • Plant-insect interactions
  • Invasion biology
  • Insect thermal ecology
  • Aquatic plant ecology
  • Biostatistics
Recent Publications

Weyl, P.S.R., Thum, R.A., Moody, M.L., Newman, R.M. & Coetzee, J.A. 2016. Was Myriophyllum spicatum L. (Haloragaceae) recently introduced to South Africa from Eurasia? Aquatic Botany, 128: 7–12.

Weyl, P.S.R. & Coetzee, J.A. 2016. Morphological variations in the southern African populations of Myriophyllum spicatum: phenotypic plasticity or local adaptation? South African Journal of Botany, 103: 241–246.

Moody, M.L., Palomino, N., Weyl, P.S.R., Coetzee, J.A., Newman, R.M., Harms, N.E., Liu, X. & Thum, R.A. 2016. Unravelling the biogeographic origins of the Eurasian watermilfoil (Myriophyllum spicatum) invasion in North America. American Journal of Botany, 103: 1 – 10.

Madeira, P.T., Hill, M.P., Dray Jr, F.A., Coetzee, J.A., Paterson, I.D. and Tipping, P.W. 2016. Molecular identification of Azolla invasions in Africa: the Azolla specialist, Stenopelmus rufinasus proves to be an excellent taxonomist. South African Journal of Botany, 105: 299–305.

Paterson, I., Mangan, R., Downie , D., Coetzee, J., Hill, M., Burke, A., Downey, P., Henry, T., & Compton, S. 2016. Two in one: cryptic species discovered in biological control agent populations using molecular data and crossbreeding experiments. Ecology and Evolution 6, 6139-6150.

Moore, S.D., Kirkman, W., Albertyn, S., Love, C.N., Coetzee, J.A. & Hattingh, V. 2016. Partial cold treatment of citrus fruit for export risk mitigation for Thaumatotibia leucotreta (Lepidoptera: Tortricidae) as part of a systems approach. Journal of Economic Entomology 109(4): 1578-85

Weaver, K.N., Hill, M.P., Hill, J.M., Coetzee, J.A., Martin, G.D., & Paterson, I.D. 2016. Community entomology: insects, science and society. Journal for New Generation Sciences in press.

Sutton, G., Compton, S., & Coetzee, J.A. 2016. Naturally occurring phytopathogens enhance biological control of water hyacinth (Eichhornia crassipes) by Megamelus scutellaris (Hemiptera: Delphacidae), even in eutrophic water. Biological Control, 103: 261-268.

Hill, M.P. & Coetzee, J.A. 2017. The biological control of aquatic weeds in South Africa: Current status and future challenges. Bothalia 47(2): 1-12.

Kwong, R., Broadhurst, L., Keener, B., Coetzee, J., Martin, G. and Kerr, N. 2017. Genetic analysis of native and introduced populations of the aquatic weed Sagittaria platyphylla (Engelm.) J.G. Sm. - implications for biological control in Australia and South Africa. Biological Control 112: 10-19.

Coetzee, J.A., Hill, M.P., Ruiz-Tellez, T., Starfinger, U. and Brunel, S. 2017. Monographs on Invasive Plants in Europe: Eichhornia crassipes (Mart.) Solms. Botany Letters 164:4, 303-326.

Jones, R.W., Hill, J.M., Coetzee, J.A. and Hill, M.P. 2018. The contributions of biological control to reduced plant size and biomass of water hyacinth populations.  Hydrobiologia 807: 377–388.

Strange, E.F., Hill, J.M. and Coetzee, J.A. 2018. Evidence for a new regime shift between floating and submerged invasive plant dominance in South Africa. Hydrobiologia 817: 349.

Martin, G.D., Coetzee, J.A., Lloyd, M., Nombewu, S.E., Ndlovu, M.S., & Kwong, R.M. 2018. Invaded habitat incompatibility affects the suitability of the potential biological control agent Listronotus sordidus for Sagittaria platyphylla in South Africa. Biocontrol Science and Technology, 28:5, 468-485,

Martin, G.D., Hill, M.P., Coetzee, J.A., Weaver, K.N. and Hill J.M. 2018. Synergies between research organisations and the wider community in enhancing weed biological control in South Africa. BioControl, 63: 437 - 447.

Martin, G.D., Coetzee, J.A. and Compton, S. 2018. Plant–herbivore–parasitoid interactions in an experimental freshwater tritrophic system: higher trophic levels modify competitive interactions between invasive macrophytes. Hydrobiologia 817: 307.

Maseko, Z., Coetzee, J.A. and Hill, M.P. 2018. The effect of shade and eutrophication on the biological control of Salvinia molesta by the weevil, Cyrtobagous salviniae. Austral Entomology.

Owen, C.A., van Noort, S., Compton, S.G. and Coetzee, J.A. 2018. Nest site choice by the intertidal spider Desis formidabilis (Araneae: Desidae) and nest utilisation by its hymenopteran egg parasitoid. Ecological Entomology.

Mvandaba, S.F., Coetzee, J.A., Owen, C.A. and Hill, M.P. 2018. The thermal physiology of Stenopelmus rufinasus and Neohydronomus affinis (Coleoptera: Curculionidae), two biological control agents for the invasive alien aquatic weeds, Azolla filiculoides and Pistia stratiotes in South Africa. Biocontrol Science and Technology. DOI: 10.1080/09583157.2018.1525484

Last Modified: Tue, 30 Oct 2018 12:09:39 SAST