Emerald ash borer (EAB), (Agrilus planipennis Fairmaire), first identified in 2002 in southeast Michigan, has caused catastrophic ash (Fraxinus spp.) mortality in forests within the core of the invasion and has spread to 35 states and five Canadian provinces. Little is known about persistence and densities of EAB populations in post-invasion sites after most ash trees have died. We monitored EAB populations from 2014 to 2016 using double decker (DD) traps set in the midst of white ash (F. americana) trees in 30 post-invasion sites in southeast and south-central Michigan. Two DD traps were deployed at each site. One trap had a dark green upper prism and light purple lower prism, both baited with cis-3-hexenol lures. The other had two dark purple prisms baited with cis-3-hexenol on the upper prism and Manuka oil on the lower prism. In 2014 and 2016, size and condition of ash trees were recorded and area of live white ash phloem was estimated in an 18-m-radius plot centered around each of the DD traps. Area of live white ash phloem per site ranged from approximately 24 to 421 m² in 2014 and from 24 to 411 m² in 2016. Canopy condition of live white ash trees generally improved; 65% and 89% of the trees had healthy canopies (<20% dieback) in 2014 and 2016, respectively. Traps in 28, 29 and 30 of the sites captured a total of 580, 585, and 932 EAB adults in 2014–2016, respectively. Area of live ash phloem explained relatively little of the variation in total EAB captures in all three years. Low trap catches, along with relatively stable canopy conditions and continued abundance of live white ash, indicate that EAB populations remain below the carrying capacity of the sites, and ash phloem availability is not a limiting factor for EAB abundance. Further monitoring to track both EAB dynamics and tree condition is needed to determine the long-term outlook for white ash in these sites.

中文翻译：

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在入侵后的白灰现场有不同数量的活韧皮部的翡翠灰Bor（Agrilus planipennis）成虫捕获

于2002年在密歇根州东南部首次发现的翡翠灰bore（EAB）（Agrilus planipennis Fairmaire）在入侵中心的森林中造成了灾难性的灰烬（Fraxinus spp。）死亡，并已扩散至35个州和加拿大的五个省。大多数灰树死后，入侵后地区EAB种群的持久性和密度知之甚少。我们使用密歇根州东南部和中南部的30个入侵后站点的白蜡木（F. americana）树中间设置的双层（DD）陷阱，对2014年至2016年的EAB种群进行了监测。每个站点部署了两个DD陷阱。一个陷阱有一个深绿色的上棱镜和一个浅紫色的下棱镜，都用顺式诱饵-3-己烯醇诱剂。另一个有两个深紫色棱镜，上棱镜上装有顺式-3-己烯醇，下棱镜上有麦卢卡油。在2014年和2016年，记录了灰树的大小和状况，并在以每个DD阱为中心的18米半径的样地中估算了活白灰韧皮部的面积。2014年每个站点的活白灰韧皮部面积范围从大约24到421 m ²，从24到411 m ²在2016年，活白灰树的树冠状况总体得到改善；在2014年和2016年，分别有65％和89％的树木拥有健康的树冠（<20％死皮）。2014-2016年，分别有28、29和30个地点的陷阱捕获了总共580、585和932个EAB成年人。活灰烬韧皮部的面积解释了在过去三年中总EAB捕获量的变化相对较小。陷阱捕获量低，加上相对稳定的树冠条件和持续大量的活白灰表明，EAB种群数量仍低于该地点的承载能力，并且烟碱韧皮部的可利用性不是EAB丰度的限制因素。需要进一步监测以跟踪EAB动态和树木状况，以确定这些场所中白灰的长期前景。