A Comparison of Girdled Ash Detection Trees and Baited Artificial Traps forAgrilus planipennis(Coleoptera: Buprestidae) Detection

Abstract

Detection of newly established populations of Agrilus planipennis Fairmaire, the most destructive forest insect to invade the United States, remains challenging. Regulatory agencies currently rely on artificial traps, consisting of baited three-sided panels suspended in the canopy of ash (Fraxinus spp.) trees. Detection trees represent another survey option. Ash trees are girdled in spring to attract ovipositing A. planipennis females then debarked in fall to assess larval presence and density. From 2008-2010, systematic grids of detection trees and artificial traps were established across a 390-km(2) area for the SLow Ash Mortality pilot project. We compared probabilities of detection associated with detection trees and artificial traps along varying A. planipennis density proxies estimated as distance-weighted averages of larval counts (detection trees) or adult captures (traps) within 800 m of each detection tree or trap. Detection trees were consistently more likely to be positive, that is, detect A. planipennis, than traps in all three years, even when traps were placed in canopies of detection trees. Probability of detection with a single detection tree was >50% when density proxies for the area were <5 larvae per detection tree, while the probability of detection with an artificial trap placed in the same area was <35%, even when density proxies exceeded 25 larvae per detection tree. At very low densities of <5 larvae per detection tree, using three detection trees would increase detection probabilities to 90%, while five artificial traps would increase the detection probability only to 40%.

Comparison Of Trap Types and Colors for Capturing Emerald Ash Borer Adults at Different Population Densities

“…The probability of detection with girdled trees was Ͼ50%, even in areas with low A. planipennis densities, where an average of only Þve larvae per tree were present when the girdled trees were debarked. In contrast, even where average larval counts exceeded 25 larvae per tree, the probability of detection with canopy traps was Ͻ35% (Mercader et al 2013).…”

“…Canopy traps can be difÞcult to hang, and it is not uncommon for traps to blow out of trees. In a recent large scale project, girdled trees and baited purple canopy traps were used to track A. planipennis distribution and density from 2008 to 2010 over an area of Ͼ750 km 2 (Mercader et al 2013). Only 3.5% of the canopy traps that were hung in girdled ash trees that were infested with A. planipennis larvae captured an adult beetle.…”

“…It also reduces the time available for municipalities and private landowners to develop plans to protect, replace, or harvest ash in landscapes and forested settings. Given the consistently higher detection or captures rates reported for girdled trees , Mercader et al 2013) and double-decker traps (Marshall et al 2010, modifying A. planipennis detection survey protocols warrants consideration. Detection methods are not mutually exclusive, and incorporating girdled trees and double-decker traps, in particular those at high risk sites, along with canopy traps and visual surveys to check declining ash trees could increase the likelihood of an early detection.…”

Condition of green ash (Fraxinus pennsylvanica) overstory and regeneration at three stages of the emerald ash borer invasion wave

“…Detection of low-density A. planipennis populations with traps or visual surveys, however, is exceedingly difficult (McCullough et al 2009a;McCullough et al 2011;Herms and McCullough 2014). The Ohio sites were almost certainly infested years earlier, given the semivoltine A. planipennis development typical in new infestations Tluczek et al 2011), the poor efficacy of the baited canopy traps at low A. planipennis densities Mercader et al 2012Mercader et al , 2013, and the tendency of A. planipennis beetles to colonize upper canopy limbs before laying eggs on the trunk (Tluczek et al 2011). There was little evidence of A. planipennis presence when our Cusp sites were originally selected, but by 2011, nearly 20% of the ash trees was dead and severe canopy dieback was apparent on another 17% of the ash.…”

Forest Health Management and Detection of Invasive Forest Insects

“…Improvements to EAB lures are still a focus of EAB detection research and the (Z)-3-hexanol lure is the current recommendation by the USDA APHIS (Animal and Plant Health Inspection Service) for trap deployment [78,88,101]. Girdled trap trees are more likely to detect EAB at low populations compared to artificial baited traps [102]. The study by Ryall et al [103] developed a detection method for urban trees that involves the collection of branches that are subsequently debarked and inspected for EAB feeding activity.…”