Weed biocontrol in the EU: from serendipity to strategy

Authors: SHAW, R - Commonwealth Agricultural Bureau International (CABI); ELLISON, C - Commonwealth Agricultural Bureau International (CABI); MARCHANTE, E - University Of Coimbra; PRATT, C - Commonwealth Agricultural Bureau International (CABI); SCHAFFNER, U - Commonwealth Agricultural Bureau International (CABI) - Switzerland; SFORZA, R - European Biological Control Laboratory (EBCL)

Submitted to: BioControl
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/31/2017
Publication Date: 10/31/2017
Citation: Shaw, R., Ellison, C., Marchante, E., Pratt, C., Schaffner, U., Sforza, R. 2017. Weed biocontrol in the EU: from serendipity to strategy. Biocontrol. 63:333. doi.org/10.1007/s10526-017-9844-6.
DOI: https://doi.org/10.1007/s10526-017-9844-6

Interpretive Summary: Controlling invasive weeds that damage natural ecosystems and crops is an increasing challenge in Europe. Biological control has been used in many countries around the world to control invasive weeds, but has been little used in Europe. This paper reviews both intentional and the serendipitous use of classical biological control agents to combat invasive weeds in Europe including: Japanese knotweed, common ragweed, long-leaved wattle, water fern, Himalayan balsam, and prickly pear. The European Union has recently developed regulations for permitting the introduction of classical biological control agents of weeds. The first insect agent authorized in Europe is a psyllid that was released in the UK in 2010 to control Japanese knotweed. It proved to be safe, but has not effectively controlled the weed. A gall wasp was authorized for introduction to Portugal in 2015 to control long-leaved wattle, and a rust pathogen to control Himalayan balsam was authorized for release in Europe in 2017. Meanwhile Europe has benefitted from the accidental introduction of several insects that are effectively reducing populations of prickly pear cactus, common ragweed, and water fern. A list of 37 plant species that are recognized as invasive aliens is beginning to be targeted for biological control.

Technical Abstract: Biological control of weeds is a globally-recognized approach to the management of the worst invasive plants in the world. Unfortunately, accidental introduction of agents account for most weed biocontrol in the EU, but do include a number of current or emerging successes. From the redistribution of the azolla weevil (Stenopelmus rufinasus) to small outbreaks of the weed, to the large scale control provided by the opuntia scale (Dactylopius opuntiae) and the ragweed beetle (Ophraella communa), EU Member States are certainly benefitting from weed biocontrol, but in a passive way. Recent programs involving the intentional introduction of agents against targets including Japanese knotweed (Fallopia japonica), Himalayan Balsam (Impatiens glandulifera) and long-leaved wattle (Acacia longifolia) show a shift from serendipity to strategy in the EU. The inclusion of new weed targets on the European Invasive Species Regulation should lead to a growth in the profile and use of this strategy though a success story from the current intentional releases would be welcome.