Reducing pest risk in birch wood products - The effective heat treatment for bronze birch borer Agrilus anxius (Coleoptera: Buprestidae) prepupae

PURPOSE: Determine the time and temperature combinations that result in partial and complete mortality of larvae of the Bronze birch borer

DESCRIPTION: The protection of forest resources and the safe trade of forest products require phytosanitary measures which reduce the risk of pest movement to novel environments. Technically sound science to develop measures are required to support safe trade policies. Heat treatment is a widely available, efficient and effective method to produce phytosanitary wood products destined for trade. Defining the optimal heat treatment dose needed to kill insects in wood products reduces the risk of spreading exotic species to new environments with the lowest possible energy cost which in turn reduces environmental impacts and provides confidence in current guidelines for heat treatment regulations. The minimum effective heat treatment dose (time and temperature) for Agrilus anxius (bronze birch borer) prepupae was determined using the Humble water bath applying heat in vitro. Heat treatment was assessed using a controlled increase in temperature to simulate the heat ramp applied to wood in industrial kilns and conventional heat chamber operations. Target temperatures between 51 and 56 °C for exposure durations of 15 and 30 min were tested to determine the minimum effective dose. Prepupal A. anxius did not survive exposure to 53, 54, 55 or 56 °C for 30 min or 54 and 56 °C for 15 min. Chronic mortality was observed at 53 °C for 15 min treatments. Evaluating the effect of specific heat treatment parameters for other forest pests is recommended to identify and validate the minimum temperature and time required to kill wood pests in order to avoid introducing exotic species with wood products and limit pest movement.

Data was collected at the following sites: Insects for these experiments were collected from trees harvested in Victoria, British Columbia and the Valcartier Research Forestry Research Station, Valcartier, Quebec. Experiments were conducted at the Pacific Forestry Centre in Victoria, British Columbia and the Laurentian Forestry Centre in Ste Foy, Quebec.

研究目的：明确可导致青铜桦窄吉丁（Bronze birch borer）幼虫出现部分死亡与完全死亡的时间与温度组合方案。
森林资源保护与林产品安全贸易需通过植物检疫措施降低有害生物传入新生境的风险。支撑安全贸易政策的研发需依托技术可靠的科学依据。热处理是生产用于贸易的检疫木质产品的通用、高效且有效的手段。明确杀灭木制品中昆虫所需的最优热处理剂量（即时间与温度组合），可在最低能耗前提下降低外来物种随木制品扩散至新环境的风险，同时减轻环境影响，并为现行热处理监管指南提供可信度支撑。
本研究采用亨布尔恒温水浴装置（Humble water bath）开展体外加热实验，测定了青铜桦窄吉丁（Agrilus anxius）预蛹的最小有效热处理剂量。实验通过可控升温过程模拟工业窑炉与常规热处理舱中木材的升温速率。测试了51℃至56℃的目标温度区间，以及15分钟、30分钟的暴露时长，以确定最小有效剂量。结果显示，预蛹在53℃、54℃、55℃、56℃下暴露30分钟，或在54℃、56℃下暴露15分钟后均无法存活；在53℃下暴露15分钟时，预蛹出现慢性死亡。研究建议针对其他森林有害生物开展特定热处理参数的评估，以明确并验证杀灭木质害虫所需的最低温度与时长，从而避免外来有害生物随木质产品传入，并限制有害生物的扩散。
数据采集地点如下：
本实验所用昆虫采集自加拿大不列颠哥伦比亚省维多利亚市采伐的桦树，以及魁北克省瓦尔卡蒂尔林业研究站的林地。实验分别在不列颠哥伦比亚省维多利亚市的太平洋林业中心，以及魁北克省圣福伊的劳伦蒂亚林业中心开展。