control options are mostly effective at a local scale but can 
also be effective at larger scales; these control options are 
limited by labour costs and generally provide short-term 
suppression but not sustained control (well established)
{5.4.3.2.a}. Furthermore, chemical control may have 
non-target impacts, needs to be implemented under 
regulatory compliance requirements and has decreasing 
societal acceptability (well established) {5.4.3.2.b}. Biological 
control has been very effective in controlling some invasive 
alien plants, invertebrates and, to a lesser extent, plant 
microbes and a few invasive alien vertebrates, but it may 
have non-target impacts if not well regulated (well 
established) {5.5.5.3}. To reduce the risks of unintended 
consequences, including non-target impacts, from biological 
control, international standards and risk-based regulatory 
frameworks (developed under the International Plant 
Protection Convention) have been applied and continue to 
be effective across many countries (well established) {5.5.2}. 
The use of biological control for invasive alien plants and 
invertebrates has been successful in more than 60 per cent 
of documented cases (Box SPM.3), with one third of the 
alien plant species requiring no further form of control, while 
also leading to benefits to biodiversity and ecosystem 
resilience (well established) {5.5.5.3}. Classical biological 
control to suppress invasive alien species populations at 
landscape scales has been effectively practised for more 
than 100 years (well established) {5.5.5.3}.
35SUMMARY FOR POLICYMAKERS
19SUMMARY FOR POLICYMAKERS
BACKGROUND
Box SPM 3 Classical biological control of Mikania micrantha (bitter vine): an example of 
effective suppression of a widespread invasive alien species.