Biological control of weeds: an analysis of introductions, rates of establishment and estimates of success, worldwide

The foremost document that comprehensively reports on biological control introductions against weeds—‘Biological control of weeds: a world catalogue of agents and their target weeds’—has been updated and now includes all deliberate releases made through 2012. It includes data on 1555 intentional releases of 468 biological control agent species used against 175 species of target weeds in 48 plant families, in 90 countries. For 55 (31.4%) of the target weed species, only one biocontrol agent was introduced. The largest number of agent species (44) was introduced for the biological control of Lantana camara (Verbenaceae). Three insect orders (Coleoptera, Lepidoptera and Diptera) comprised about 80% of all biocontrol agent species released and releases made. Of the 468 biocontrol agent species introduced, 332 (70.9%) established in at least one instance. Of the 313 species, for which impact could be categorized, 172 (55.0%) caused medium, variable or heavy levels of damage (impacts). Of all releases made through 2012, 982 (63.2%) led to establishment. Forty-two releases were judged too early post-release to categorize impact, leaving 940 releases for which impact analyses were conducted. Similar to agent species, approximately half of the established releases (503 or 53.5%) caused medium, variable or heavy levels of damage on the target weeds, and almost a quarter of releases (225 or 23.9%) caused heavy impact. Across all countries and regions, 65.7% of the weeds targeted for biological control experienced some level of control. These data indicate the value of this practice, on its own, or as a supplement to other methods, in the management of invasive plants.