Emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), is one of the most serious forest pests in the United States. Ongoing research indicates that establishment of larval parasitoids depends upon the season-long availability of host stages susceptible to parasitism. We monitored emerald ash borer overwintering stages at 90 sites across 22 states to: 1) produce a model of the percentage of emerald ash borer overwintering as non-J larvae; 2) link that model to establishment of Tetrastichus planipennisi; and 3) explore changes to our model under climate change scenarios. Accumulated growing degree days (GDD) is an important predictor of the proportion of emerald ash borer overwintering as non-J larvae (1-4 instar larvae under the bark; available to parasitoids emerging in spring) versus J-larvae (fourth-instar larvae in pupal chambers in the outer wood; unavailable to parasitoids). From north to south, the availability of non-J emerald ash borer larvae in the spring decreases as accumulated GDD increases. In areas where the model predicted >46-75%, >30-46%, >13-30%, or ≤13% of emerald ash borer overwintering as non-J larvae, the probability of establishment of T. planipennisi was 92%, 67%, 57%, and 21%, respectively. We determined that 13% of emerald ash borer overwintering as non-J larvae was the lowest threshold for expected T. planipennisi establishment. Additional modeling predicts that under climate change, establishment of T. planipennisi will be most affected in the Central United States, with areas that are currently suitable becoming unsuitable. Our results provide a useful tool for the emerald ash borer biological control program on how to economically and successfully deploy emerald ash borer biological control agents.

中文翻译：

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宿主越冬物候和气候变化影响 Tetrastichus planipennisi Yang（膜翅目：Eulophidae）的建立，这是一种用于生物防治翡翠灰螟的幼虫寄生蜂

翡翠灰螟（Agrilus planipennis Fairmaire）（鞘翅目：Buprestidae）是美国最严重的森林害虫之一。正在进行的研究表明，幼虫寄生蜂的建立取决于易受寄生的寄主阶段的整个季节可用性。我们在 22 个州的 90 个地点监测了翡翠灰螟越冬阶段，以：1) 生成翡翠灰螟作为非 J 幼虫越冬的百分比模型；2) 将该模型与 Tetrastichus planipennisi 的建立联系起来；3) 在气候变化情景下探索我们模型的变化。累计生长度日（GDD）是翡翠灰螟以非J幼虫（树皮下1-4龄幼虫）越冬比例的重要预测指标。可用于春季出现的寄生蜂）与 J 幼虫（四龄幼虫在外部木材的蛹室中；寄生蜂不可用）。从北到南，随着累积 GDD 的增加，春季非 J 祖母绿灰螟幼虫的可用性降低。在模型预测 >46-75%、>30-46%、>13-30% 或≤13% 的翡翠灰螟作为非 J 幼虫越冬的地区，T. planipennisi 的建立概率为 92% 、67%、57% 和 21%。我们确定 13% 的翡翠灰螟作为非 J 幼虫越冬是预期 T. planipennisi 建立的最低阈值。附加模型预测，在气候变化下，T. planipennisi 的建立将在美国中部受到最大影响，目前适合的地区将变得不适合。