Herbivores and Pathogens Used for Biological Weed Control

Biological weed control has been achieved through two routes: introduction of natural enemies against adventive and native weeds (usually using agents collected from an adventive weed’s native range), and augmentation of natural enemies which are released or applied at specific locations where control is needed (Wapshere et al. 1989). Introduction of natural enemies has employed mostly insects, a few other arthropods, some species of fungi, and one nematode. Biological control of weeds through the augmentation of natural enemies has employed almost exclusively various pathogenic fungi and generalist vertebrate herbivores, almost entirely fish. Potential may exist to exploit additional categories of plant pathogens. Fish have been employed for suppression of whole aquatic weed communities in irrigation canals, tanks, ponds, and lakes. This chapter reviews the taxonomic groups of herbivores and pathogens which have been employed in weed biological control and discusses basic elements of their natural history. Chapter 17 discusses key aspects of herbivore biology that are pertinent to weed biological control.