Lessons from three cases of biological control of native freshwater macrophytes isolated from their natural enemies

Abstract

Classical biological control–or biocontrol–is a form of pest management comprising the release of specialized natural enemies (biocontrol agents) of an exotic pest. Classical biocontrol agents are scientifically selected from among the natural enemies the pest has in its native region. However, biological control is firmly resisted in many countries because of the belief that it is more risky than not doing anything, or using the more familiar chemical and mechanical control methods. In this review, three classical biocontrol projects from Argentina are described. These projects had the peculiarity that native insects were used to control two native aquatic plants–Water Hyacinth and Water Lettuce–in isolated water bodies where their natural enemies were absent. In two of these projects complete control of the weeds were achieved, and preliminary results are quite promising for the most recent project, as well. This article stresses that classical biocontrol can be applied in a weed's native range under special circumstances, and describes why such cases can be used to promote biological control of native invaders while circumventing the more resisted aspect of classical biocontrol: introducing exotic species.