Scientists Aim Natural Enemy at Water Weed. (22 October, 1996)

Lusaka - Zambian scientists, working to find a weapon against the fast-growing water hyacinth, an aquatic weed that has spread through parts of the Kafue River, have turned to a natural antidote - weevils, imported from South Africa's Plant Protection Research Institute. The tenacious water hyacinth, known locally as the obnoxious Kafue River weed or majavani, has clogged part of the river.

Its rapid growth is attributed to chemicals dumped into Zambia's longest interland river by factories. The chemicals provide nutrients for the aquatic plant pests. Zambian authorities are concerned about the weed-clogged river. Energy Minister Edith Nawakwi says the weeds threaten electricity generation at the Kafue Gorge power station. Various efforts against the hyacinth have proved unsuccessful. The war of the weeds has reached a stalemate at best.

In an attempt to fight the weed, the Environmental Council of Zambia (ECZ) and the National Council for Scientific Research (NCSR) are culturing weevils locally in ten tanks situated at the NCSR's research premise in Lusaka. The first batch of home-grown weevils has already been released into the river, according to Patrick Brigham, a technical officer with the council. 'We feel this is the ultimate panacea for the effective control of the problematic water hyacinth,' he said.

The ECZ is now monitoring the biological effects following the release of 16 000 weevils cultured from the local environment into the Kafue River stretching from the Kafue Gorge power generation station upstream to the Nitrogen Chemicals of Zambia intake pump. The release of 16 000 home-grown neochetna eichorniac, or weevils, is the second biological control measure against the aquatic weeds, wich have infested the 16 km-stretch downstream of the Kafue Gorge in recent years.

The weevils are host-specific, and do not feed on any other plants or crops apart from the hyacinth. Shadrack Nsongela, a senior education and communication officer with the Environmental Council, said biological remedies were the only remedial measures against weeds that had proven environmentally friendly. The Kafue weed control effort is funded by the Commonwealth Scientific Council in co-operationwith the Department of Entomology Research Organisation of Australia and the Plant Protection Research Institute of South Africa. Sapa-dpa. Courtesy of The Star.