A global evaluation of classical biological control against weeds
Although only a small proportion of naturalised plant species have negative impacts on native biodiversity and ecosystem services, those that do can cause significant economic damage to agriculture, forestry and infrastructures as well as threatening native biodiversity. Some alien plant species have invaded such wide areas that commonly used control methods are often not economically viable to manage these species and other control techniques are needed. Classical biological control (the utilization of host specific natural enemies from the plants’ native range) is an alternative method for the management of invasive alien plants and has shown some significant successes in reducing invasive populations throughout the world. Using data from the fifth edition of the ‘Biological control of weeds: a world catalogue of agents and their target weeds’, the authors identified all cases where a weed biological control agent was intentionally released against a target up to 2012. In total, 1 555 releases of 468 biological control agents have been utilised against 175 plant species in 48 plant families in 90 countries. For 31.4 % of targets, only one agent has been introduced and the largest number of agents (44) released against one species was for Lantana camara. Of the 313 species where impact could be categorized, 172 (55 %) caused medium, variable or heavy levels of damage. In total, 65.7 % of weeds targeted for biological control experienced some level of control indicating the value of the management method.
Sources
Schwarzländer M, Hinz HL, Winston RL, Day MD (2018) Biological control of weeds: an analysis of introductions, rates of establishment and estimates of success, worldwide. BioControl 63, 319-311.