Risk-based strategies to prepare for and manage invasive tree borers (PREPSYS)
Extensive literature review and interactions with researchers and managers dealing with Agrilus planipennis (emerald ash borer, EAB) and Agrilus anxius (bronze birch borer, BBB) has assessed the ‘state of the art’ as a basis for potential invasion of Europe by these pests.
Although there is increasing information on the two pest species, further work especially from a European perspective is required to both anticipate and to react to incursions of the pests. The PREPSYS project addressed key questions and gaps in our knowledge on the pests’ biology, control (including firewood risks and treatments and biological control agents), dispersal and economic/environmental impacts. PREPSYS has pulled together the accumulated knowledge on EAB and BBB to prepare a European Toolbox for their detection and management and this has been published in a recent special edition of Forestry: An International Journal of Forest Research. This can form the basis for a coordinated approach to deal with the very real threats from EAB and BBB.
It is known from North America and European Russia that there is usually a gap of several years between arrival and first detection of EAB. PREPSYS has assessed the range of options for survey and early detection of EAB or BBB and concluded that girdling of trees (stressing the trees) is the most effective for this purpose. However, there are logistic problems in using this technique and so use of traps with chemical lures is often more practical; a range is available with similar efficiencies in capturing adult beetles.
Management of infestations is usually through felling of infested or dead trees and this is an expensive and time-consuming procedure. Extensive research in North America indicates that slowing progress of infestations using trunk injections of the insecticide Emamectin benzoate is an effective process to ‘buy time’ for selective felling and other measures. It is recommended that registration of the insecticide for use in Europe should be carried out urgently.
In the longer term, introduction of parasitoids (natural enemies) from the native ranges of EAB is now becoming more effective after a slow initial period after releasing species from China and Russia. There is also detailed knowledge of the climatic requirements of these classical biological control agents and this has improved establishment and efficacy. Since there is a need for assessment of possible adverse impacts on non-target species, tests for potential use of these agents in Europe should be carried out urgently. Methods for mass production are, fortunately, already developed in the USA.
Outreach and information provision are an important part of detection and management of EAB and information should be made increasingly available in Europe to prepare for the likely arrival of EAB from European Russia, Ukraine or any of the infested regions of the world.