Department of Entomology, University of Maryland, College Park, MD, USA.
Beneficial Insects Introduction Research Unit, USDA - Agricultural Research Service, Newark, DE, USA.
Pest Manag Sci. 2021 Jan;77(1):474-481. doi: 10.1002/ps.6041. Epub 2020 Sep 11.
The emerald ash borer (EAB) (Agrilus planipennis Fairmaire) (Coleoptera: Buprestidae) is now the most destructive invasive species in North America. While biocontrol using parasitoids shows promising results in natural forests, strategies are needed to protect high-value trees against invasive EAB populations. Emamectin benzoate is a commonly used systemic insecticide for the protection of valuable trees. Methods that optimize its use allow for reduced quantities of insecticide to be released in the environment and save time and money in efforts to protect ash trees from EAB. We hypothesize that a treated tree can also offer a protective neighboring effect to nearby untreated ash trees, allowing for an optimized spatial planning of insecticide applications.
We sampled 896 untreated ash trees, in the vicinity of treated trees, in Maryland and Washington DC. We recorded signs of EAB infestation (canopy condition, exit holes, wood pecks, epicormic growth, and bark splits). Two subsequent yearly samplings were made of 198 and 216 trees, respectively. We also present a novel proximity index for this particular application. Results show consistent decrease in EAB infestation signs in untreated trees as proximity to treated trees increases.
Results support that a neighboring effect occurs. However, proximity to treated trees must be high for a tree to be safely left untreated. This proximity seems rare in forests, but can happen in urban/planted landscapes. Future studies should test and validate these findings, and could lead to a more precise recommended safe index tailored across multiple ash species and geographic regions.
翡翠灰螟（EAB）（Agrilus planipennis Fairmaire）（鞘翅目：扁甲科）现已成为北美最具破坏性的入侵物种。虽然利用寄生蜂进行生物防治在天然林中有很好的效果，但仍需要制定策略来保护高价值的树木免受入侵 EAB 种群的侵害。甲氨基阿维菌素苯甲酸盐是一种常用于保护珍贵树木的内吸性杀虫剂。优化其使用方法可以减少杀虫剂在环境中的释放量，并节省保护灰树免受 EAB 侵害的时间和资金。我们假设，处理过的树木也可以对附近未处理的灰树产生保护邻接效应，从而优化杀虫剂的空间规划。
我们在马里兰州和华盛顿特区附近的 896 棵未处理的灰树上进行了采样，记录了 EAB 感染的迹象（树冠状况、出口孔、木啄、愈伤组织生长和树皮裂缝）。随后在两年内分别对 198 棵和 216 棵树进行了两次采样。我们还提出了一种用于这种特殊应用的新的邻近指数。结果表明，随着与处理树木的距离增加，未处理树木中 EAB 感染迹象持续减少。
结果支持邻接效应的发生。然而，树木要安全地不进行处理，其与处理树木的距离必须足够近。这种接近在森林中很少见，但在城市/种植景观中可能会发生。未来的研究应该测试和验证这些发现，并可能导致针对多个灰树物种和地理区域的更精确的推荐安全指数。
