Opportunities for classical biological control of weeds in European overseas territories.
European overseas territories are home to biodiversity and endemism of worldwide importance, vastly superior to that of continental Europe as a whole. They are, however, much more threatened by invasive species, including hundreds of alien invasive plant species having a huge impact on natural and agricultural habitats. As in continental Europe, invasive plants have only recently been recognized as a threat to the local environment and biodiversity. Mechanical and chemical control programmes - underway for several decades - have not been entirely successful for permanent, costeffective, environment-friendly management. Biological control of weeds has long been successfully used in other neighbouring countries with similar climates, environmental conditions and invasions, but has barely been implemented in European overseas territories. There have been very few attempts to set up classical biological control programmes in these regions - a few of the species that have been the focus of biological control are Lantana camara L., Rubus alceifolius Poir., Opuntia stricta (Haw.) Haw., Acanthocereus tetragonus (L.) Britton & Rose, Ligustrum robustum (Roxb.) Blume, Miconia calvescens DC., Ulex europaeus L., Prosopis juliflora (SW.) DC., and Leucaena leucocephala (Lam.) de Wit. Many invasive plants occurring in European overseas territories are also invasive elsewhere and already targets of biological control programmes. Biological control agent specificity requires particular attention due to the high level of endemism in such islands. This paper reviews some of the most threatening species for which classical biological control could be achieved through regional or international collaboration.