Resurgence and Control of Water Hyacinth at a Neochetina eichhorniae Release Site in Bangalore, India

Many of the large number of aquatic plants growing in India are of exotic origin (Gupta, 1976). Among these, water hyacinth (Eichhornia crassipes), the free-floating weed of south American origin, infesting more than 200,000 ha of water surface (Anon, 1989), is considered to be the most serious. Two weevils, Neochetina eichhorniae Warner and N. bruchi Hustache (Coleoptera:Curculionidae) introduced from the U.S.A., have proved to be effective biological control agents of water hyacinth under field conditions (Jayanth 1988 a, b).