Department of Environmental Biology, SUNY College of Environmental Science and Forestry, 1 Forestry Drive, Syracuse, NY 13210, USA.
USDA Animal and Plant Health Inspection Service, Plant Protection and Quarantine, Science and Technology, 1398 West Truck Road, Buzzards Bay, MA 02542, USA.
J Econ Entomol. 2023 Aug 10;116(4):1155-1164. doi: 10.1093/jee/toad111.
Forest stands infested by emerald ash borer (EAB), Agrilus planipennis Fairmaire, experience extensive mortality of mature ash trees. Post-invasion woodlands commonly have a small contingent of mature lingering ash, an orphaned cohort of seedlings/saplings, and low EAB densities. To protect regenerating ash against rebounding EAB populations, a suite of biocontrol agents are being reared and released. USDA APHIS guidelines currently recommend the release of parasitoids into forests prior to overstory ash mortality at sites containing a variety of ash size classes and low to moderate but building EAB densities. To understand if biocontrol establishment and control of EAB is feasible in post-invasion sites, we assessed the establishment of parasitoids in 6 post-invasion forest stands in 2 regions of NY and compared EAB mortality in these stands to 2 regions where releases were conducted during the early-invasion phase. Results of parasitoid trapping indicates Tetrastichus planipennisi Yang established under both release strategies. Spathius galinae Belokobylskij & Strazanac was only released in post-invasion stands, where it was established successfully. Artificial EAB cohorts were established and life tables were constructed at 3 sites per region. EAB mortality due to T. planipennisi parasitism was similar under both release strategies 2 yr after release in post-invasion stands versus 8 yr after release in early-invasion stands. Combined mortality from T. planipennisi and woodpecker predation resulted in consistently low EAB reproductive rates. Future biocontrol releases could target forests identified as economically or ecologically important, regardless of whether EAB populations are increasing or have collapsed following initial invasion.
受翡翠灰螟（EAB）侵袭的森林中，朴喙丽象甲（Agrilus planipennis Fairmaire）大量杀死成熟的白蜡树。入侵后林地通常有一小部分成熟的残留白蜡树、一批孤立的幼苗/幼树和低水平的 EAB 密度。为了保护再生的白蜡树免受反弹的 EAB 种群的侵害，正在培育和释放一系列生物防治剂。美国农业部动植物卫生检验局（APHIS）目前的指南建议，在含有各种白蜡树大小等级和低到中等但不断增加的 EAB 密度的地点，在林冠层白蜡树死亡之前，将寄生蜂释放到森林中。为了了解生物防治在入侵后地点的建立和对 EAB 的控制是否可行，我们评估了在纽约的 2 个地区的 6 个入侵后森林中的寄生蜂建立情况，并将这些地点的 EAB 死亡率与在入侵早期阶段进行释放的 2 个地区进行了比较。寄生蜂诱捕的结果表明，在这两种释放策略下，平腹小蜂（Tetrastichus planipennisi Yang）都建立了起来。横纹金小蜂（Spathius galinae Belokobylskij & Strazanac）仅在入侵后林分中释放，在那里成功建立。在每个地区的 3 个地点建立了人工 EAB 群体并构建了生命表。在入侵后林分中，释放后 2 年，T. planipennisi 寄生导致的 EAB 死亡率与释放后 8 年在入侵早期林分中的死亡率相似。T. planipennisi 和啄木鸟捕食的综合死亡率导致 EAB 的生殖率始终较低。未来的生物防治释放可以针对被认为具有经济或生态重要性的森林，无论 EAB 种群是在最初入侵后增加还是已经崩溃。
