Success in Biological Control of Aquatic Weeds by Arthropods

Aquatic vascular plants have successfully colonised fresh waters in all climatic zones and although most species are rooted in the substrate, a few float freely. Most species have structural modifications that enhance their ability to survive in or on water and some exhibit extreme phenotypic plasticity. There are tendencies for aquatic plants to reproduce vegetatively rather than sexually (Sculthorpe, 1967) and their high rate of assimilation of nutrients (Spencer and Bowes, 1990) results in rapid growth and increase in biomass. Often the explosive growth of aquatic weeds in tropical countries is caused by human interference with their habitat, by the introduction of an invasive exotic plant or by a combination of both (Pieterse, 1990).