Wood Borer and Bark Beetle Risk Analysis E.G. Brockerhoff May 2009 Source: www.mountainpinebeetle.com Wood Borer and Bark Beetle Risk Analysis E.G. Brockerhoff Date: May 2009 Client: Forest Biosecurity Research Council Contract No: Disclaimer: In producing this publication reasonable care has been taken to ensure that all statements represent the best information available. However, the contents are not intended to be a substitute for specific specialist advice on any matter and should not be relied on for that purpose. SCION and its employees shall not be liable on any ground for any loss, damage, or liability incurred as a direct or indirect result of any reliance by any person upon information contained or opinions expressed in this work. EXECUTIVE SUMMARY Wood borers and bark beetles are among the most serious forest pests world-wide, and many species have become successful invaders beyond their native range. International trade in forest products and, in particular, the widespread use of wood packaging materials have been identified as significant pathways for the introduction of such borers. New Zealand already operates well developed high-risk site and forest health surveillance programmes which should facilitate the detection of new invaders. However, a recent external evaluation of New Zealand’s Forest Health Surveillance (FHS) programme, which was commissioned by the Forest Owners Association (NZFOA), recommended the implementation of a network of traps for detecting wood-boring insects across New Zealand on an operational basis. A trap-based surveillance programme may lead to earlier detection and, therefore, an increased likelihood of successful eradication or other emergency response. But such a programme also comes at a cost, and there is some uncertainty among stakeholders whether the risks posed by borers and the benefits of an additional surveillance programme justify this expenditure. The objectives of this report were, therefore, to estimate the risk of establishment of exotic wood- and bark-boring insects and the potential damages that could result, to determine the efficacy of traps for detecting a newly introduced wood- and bark-boring insect and the subsequent probability of successful eradication, and to weigh up the costs and potential benefits of a trap-based surveillance programme. A review of historical records of interceptions and establishments in New Zealand and overseas indicates that there have been numerous interceptions of borers that pose serious biosecurity risks to New Zealand’s plantation forests (and to trees in other production, natural or urban ecosystems). Among the more serious invaders are Dendroctonus valens which kills pines in China, and Ips grandicollis which currently has serious outbreaks in parts of Australia where it causes mortality of radiata pines. In New Zealand, relatively few establishments of such species have occurred but cases recorded in other countries demonstrate that the risk is high. Border interceptions and establishments of borers have increased in the last two decades as a result of growing international trade, although phytosanitary measures in New Zealand and internationally (e.g., ISPM 15) have counteracted this to some degree. Trap-based surveillance programmes for borers have been implemented in various countries (e.g., Australia, USA), and these have been successful. An ongoing programme in the USA that started in 2001 detected one new species per year, on average, over the following five years. Among the detections was one new species attacking pines (and other Pinaceae), Hylurgops palliatus. In New Zealand, a similar programme run by MAF-Biosecurity New Zealand was in operation for three years until 2005 (no new species were detected), but it was discontinued because of a lack of funding. However, a programme is most useful as an early warning system when it operates continuously, so it enables detections of new incursions as early as possible, ideally before any significant spread has occurred. The potential benefits of a reinstated borer surveillance programme, in terms of averted losses, need to be balanced against the costs of a programme. If there were no new establishments, costs would exceed the benefits. Conversely, if a trap- based programme were to lead to the early detection of a new borer with a potentially significant impact on New Zealand’s forests and forest industry, then there is a high probability of significant net benefits resulting from the ability to respond more rapidly to this incursion. TABLE OF CONTENTS 1. Introduction-----------------------------------------------------------------------------------------------------1 2. Background ----------------------------------------------------------------------------------------------------1 3. Methods---------------------------------------------------------------------------------------------------------4 3.1. Risk of establishment:--------------------------------------------------------------------------------------4 3.2. Potential damage and economic impacts: ------------------------------------------------------------4 3.3. Surveillance efficacy:---------------------------------------------------------------------------------------4 3.4. Costs and benefits of a surveillance programme: ---------------------------------------------------4 4. Results and discussion--------------------------------------------------------------------------------------4 4.1. Risk of establishment of wood- and bark-boring insects and current arrival rate ------------4 Exotic species established in New Zealand -------------------------------------------------------------4 Exotic species established overseas----------------------------------------------------------------------6 Historical and recent border interceptions in New Zealand and overseas -----------------------9 Pathways ------------------------------------------------------------------------------------------------------11 4.2. Potential damage and economic impacts -----------------------------------------------------------13 4.3. Surveillance methods and efficacy--------------------------------------------------------------------15 4.4. Costs and benefits of a surveillance programme--------------------------------------------------16 Costs of a surveillance programme ---------------------------------------------------------------------16 Potential benefits of a surveillance programme ------------------------------------------------------17 Arrival rate -------------------------------------------------------------------------------------------------17 Risk of establishment------------------------------------------------------------------------------------18 Averted costs due to surveillance --------------------------------------------------------------------18 Other benefits ---------------------------------------------------------------------------------------------18 Conclusions ------------------------------------------------------------------------------------------------------18 Acknowledgements---------------------------------------------------------------------------------------------19 References -------------------------------------------------------------------------------------------------------19 1. Introduction Wood borers and bark beetles are among the most serious forest pests. Numerous species have become established outside their native range, and some groups are generally regarded to present a high risk to forest biosecurity. Currently there are targeted surveillance programmes for such borers in Australia, the United States, and other countries (see below). In 2007, the New Zealand Forest Owners’ Association (NZFOA) commissioned an external evaluation of New Zealand’s current Forest Health Surveillance (FHS) programme (Liebhold and Callan 2007). One of the recommendations of the evaluation was to implement a network of traps for detecting wood-boring insects across New Zealand on an operational basis . Subsequently the need for further information about the rationale for such a surveillance programme was raised. Here we present a review of the risks associated with exotic wood- and bark-boring insects that have been recorded on Pinus species and other Pinaceae but are not present in New Zealand. Some relevant cases concerning other tree species are also discussed. The review will also discuss the kinds of damage that could potentially occur in New Zealand’s plantation forests if an exotic wood- or bark-boring insect did establish, based on experience in other countries. This work will contribute to an evaluation of the potential benefit of carrying out a trapping programme aimed at early detection of wood- and bark-boring insects, based on experience in New Zealand and overseas. The Forest Biosecurity Research Council commissioned this review to address the points above. Note: this report is not a standard pest risk analysis of wood borers and bark beetles. The objectives of this study were: • To estimate the risk of establishment of exotic wood- and bark-boring insects based on historical records of interceptions and establishments in New Zealand and overseas. • To estimate the potential for ‘damage’ to trees, forest products, or trade if a wood- and bark- boring insect became established in New Zealand, based on overseas and local experience. • To determine the efficacy of traps for detecting a newly introduced wood- and bark-boring insect and the subsequent probability of successful eradication. • To comment on the