Detection probability of forest pests in current inspection protocols – A case study of the bronze birch borer

Abstract

Increasing inter-continental trade of wood chips for biofuel represents a significant risk of introducing invasive pest species that can cause biome-scale impacts on forest ecosystems. Some potentially invasive species have the capacity to cause high tree mortality on the Eurasian continent and could cause significant impacts on biodiversity and ecosystem functions. Because eradication of established species is difficult, there is a need for scientific studies that can evaluate the reliability of current import control practices to ensure lowest possible risk of establishment of potentially harmful species. We used a stochastic simulation model and sensitivity analyses to evaluate the chance of detecting harmful pests in imported wood chips by sampling according to the current use of internationally accepted standards. As an example, we focused on the North American beetle Agrilus anxius (bronze birch borer) that can cause 100% mortality of European and Asian birch species in North America. We simulated the process from logging in North America to sampling the wood chips upon arrival in Europe. The probability of pest detection for current sampling protocols used by port inspectors was very low (B0.00005), while a 90% chance of detection may require sampling 27 million litres of wood chips per shipload.

A Review of Bronze Birch Borer (Coleoptera: Buprestidae) Life History, Ecology, and Management

“…Considering the high susceptibility of European and Asian birch species planted in North America to bronze birch borer (Nielsen et al 2011), the inadvertent introduction and establishment of this beetle to Eurasia could threaten birch species there on a continental scale (EPPO 2011, Nielsen et al 2011, Økland et al 2012, just as the establishment and spread of emerald ash borer in North America threatens the survival of ash species in North America (Poland and McCullough 2006). Birch species exist throughout most of Europe and Asia and are dominant in some areas, comprising as much as 28% of the total volume of growing stock (Hynynen et al 2010).…”

“…The high susceptibility of Eurasian birch species and climatic similarities of North America and Eurasia where Betula spp. exist, suggest a high risk of establishment and spread throughout Eurasia if bronze birch borer were to be inadvertently introduced (EPPO 2011, Nielsen et al 2011, Økland et al 2012.…”

Importing deciduous wood chips from North America to northern Europe – the risk of introducing bark- and wood-boring insects

“…Extensive tree killing and severe ecological consequences are also expected if A. anxius is introduced to northern Europe (EPPO 2011b; Nielsen et al 2011), as potentially susceptible birch species are important and widely distributed throughout Eurasia (Hultén & Fries 1986). Effects of widespread killing of ash and birch forest in Eurasia by A. planipennis and A. anxius may include changes in the composition of the fauna and flora associated with these forests due to altered tree species composition, extinction of species dependent on ash or birch, and extensive erosion and mobilization of carbon stores in the soil (Gandhi & Herms 2010;Økland et al 2012). Introduction of H. rufipes to northern Europe could increase the spread of DED, one of the most destructive forest pathogens of all times, which has killed hundreds of millions elms in Europe and North America over the past decades (Brasier & Buck 2001).…”

Invasion potential of Agrilus planipennis and other Agrilus beetles in Europe: import pathways of deciduous wood chips and MaxEnt analyses of potential distribution areas

“…One fundamental problem with using trade data to identify high‐risk imports and quantify risks is that the biological resolution of the Eurostat data tends to be low. Wood chip consignments often include a mixture of tree species with different probabilities of containing harmful Agrilus species, but unfortunately there is no information about tree species composition in the trade data and it is difficult and time‐consuming to obtain such data upon inspection (Økland et al ., ). The biological state of the wood used for chipping may also vary much between consignments, but again it is impossible to separate high‐ and low‐quality wood chips based on the trade data alone.…”