Latin American weed biological control science at the crossroads.

Abstract

Latin America is the centre of origin of many of the invasive alien weeds threatening natural and agricultural ecosystems throughout the world. As a result, it has been an important destination for expeditions in search of natural enemies for their control. Unfortunately, the role of local scientists has been mainly that of contracted explorers, cooperating on projects aimed at exploration for classical biological control agents. This is changing as the need to confront the growing threat from alien weeds in Latin America gathers pace. Nevertheless, with limited funding and a continuing ignorance by both the general public and the decision makers about the scale of the invasive weed problem in Latin America, target selection will be critical since this will determine the long-term viability of biological control in the region. In the proactive, new role to develop biological control in Latin America, should 'easy' targets be selected, for which there has been success on other continents, or instead, should targets be more challenging, potentially confrontational, such as African grasses which threaten not only the stability of unique ecosystems but which could also have global consequences? These issues will be discussed based on experiences gained from past and present collaborative projects. Latin American weed biological control: historical backgroundLatin America, including the Caribbean in this paper, is the centre of origin of many of the invasive alien weed threatening systems throughout the world. For instance, 59 of the 209 worst weeds on a worldwide scale are native to Latin America (Cronk and Fuller, 1995). They include aquatic weeds such as water hyacinth, Eichhornia crassipes (Mart.) Solms; alligator weed, Alternanthera philoxeroides (Mart.) Griseb.; capybara grass, Hymenachne aplexicaulis (Rudge) Nees; water lettuce, Pistia stratiotes L.; arrowhead, Sagittaria motevidensis Cham. and Schlecht.; and salvinia, Salvinia molesta D.S. Mitchell; and terrestrial weeds such as mistflower, Ageratina riparia (Regel) King and Robinson; Siam weed; Chromolaena odorata (L.) King and Robinson; lantana; Lantana camara L.; mile-a-minute Mikania micrantha H.B.K.; sensitive plant, Mimosa spp.; prickly pear, Opuntia spp.; strawberry guava, Psidium cattleianum Sabine; and Brazilian pepper tree, Schinus terebinthifolius Raddi.Latin America has played a major role in weed biological control since its inception at the beginning of the 20th century. Two early pioneering projects were involved in transcontinental transfers of natural enemies aimed at L. camara and Opuntia vulgaris Miller.

Optimal Integrated Strategies to Control an Invasive Weed

“…Blackberry also infests many natural ecosystems in the United States (Pemberton 2000), New Zealand (Quinn 1997), Latin America (Barreto 2009), and Australia (Anonymous 2006), the focus of this study. Blackberry is also a threat to the Canadian natural environment (Cogliastro et al 2006).…”