Weevils tame unruly hyacinth

A new control methodology that uses weevils has resulted in a near 80% reduction of the notorious water hyacinth, Eichornia crassipes, in Uganda. As weevil damage reduces leaf area and root length, the affected plants cannot grow or produce new plants. Water hyacinth has been labelled the world's worst aquatic weed because of its detrimental effects. Floating in enormous mats, the weed chokes canals and harbours, blocks water intakes for hydropower plants and urban water supply, makes fishing virtually impossible, and provides a breeding ground for the vectors of such diseases as malaria and bilharzia. In eastern Africa, water hyacinth was first reported as a serious nuisance in the late 1980s. Initial attempts in Uganda to control the weed by physical eradication failed. In 1993, UgandaÕs National Agricultural Research Organisation (NARO) started trials with Neochetina weevils, the hyacinth's natural enemies. Neochetina bruchi and Neochetina eichorniae were imported from Benin, and mass reared in tanks on the shores of Lake Kyoga and Lake Victoria. Periodically, adult weevils were released by fishermen, who played a key role in the rapid distribution of the weevils in the lakes. Professor J K Mukiibi NARO PO Box 295, Entebbe, Uganda Fax: +256 41 321 070 Email: narohq@imul.com