BIOLOGICAL-CONTROL OF WATER HYACINTH, EICHHORNIA-CRASSIPES (PONTEDERIACEAE), IN SOUTH-AFRICA

Water hyacinth, Eichhornia crassipes (Mart.) Solms-Laub., is the most important aquatic weed in South Africa. Chemical and mechanical control of the plants has proved unsatisfactory, and biological control is considered the best long-term solution to the problem. A weevil, Neochetina eichhorniae Warner, which has provided effective control in other parts of the world, has been released and become established on E. crassipes in South Africa. In the fourth year after release, the weevil is showing some effect on the water hyacinth populations. Other insect species are under consideration for importation. The biocontrol programme against E. crassipes in South Africa is reviewed and discussed.