To celebrate National WeedBuster Day (16 October, 2013), staff from the Invasive Species Unit was joined by Walter Williams, from the Stormwater department of the City of Cape Town, to release a hopper insect (Megamelus scutellaris) into Zeekoevlei to help control the spread of invasive water hyacinth, the world’s worst aquatic weed.
The new water hyacinth hopper originates from Argentina and was released for the first time in South Africa after extensive research by entomologists at Rhodes University, Grahamstown, who work on the effectiveness of various biological control agents (insects, mites and pathogens) for water hyacinth.
In a pioneering joint venture between Rhodes University and the City’s Environmental Resource Department’s Invasive Species Unit, Zeekoevlei was chosen as the site for the release of the water hyacinth hopper. The area where the water hyacinth hopper insect was released at Zeekoevlei is largely inaccessible to control teams as it is the home range of the City’s hippopotamus family. Working in this area is therefore particularly dangerous for the Kader Asmal river warden teams. The chosen site is densely invaded with water hyacinth and is an ideal spot for releasing natural enemies to control the infestation because once released, they multiply and remain in the area.