Biological control of weeds in Latin America

Abstract

 Biological Control of Weeds (BCW) has been successfully utilized worldwide since the beginning of this century. Between 1902 and 1980, 174 projects were initiated to control 101 species of weeds; 68 (39%) projects provided partial to total control of 48 species. At present, since the most difficult weeds remain uncontrolled, the success rate has decreased to about 15%. However, these results are permanent, highly economic and harmless for the ecosystems. In Latin America (neotropics) 13 species of natural enemies have been introduced against 10 species of weeds, five of which have been partially or totally controlled. The first project on BCW in the neotropics was carried out by Chile in 1952 with the introduction of two species of insects for the control of the weed Hyericum perforatum. In the last two decades the method has received some attention from other countries of the region but, nevertheless, the activities related to BCW are barely noticeable. Presently only 3 countries have projects in BCW: Chile (3), Brazil (5) and Argentina (3). This reflects the lack of interest in this method, specially if it is compared with the remarkable developments related to BC of insect pests which have taken place in the last decade in most of the neotropical countries. The possible causes of the low activity of BCW are discussed in this paper: lack of confidence in its effectiveness, ignorance regarding methodologies and the overestimated risk of introducing potential pests are mentioned here. Finally, means and ways to stimulate the use of BCW are proposed.