338 Anulewicz et al.: Emerald Ash Borer Density and Canopy Dieback in Ash Arboriculture & Urban Forestry 2007. 33(5):338–349. Emerald Ash Borer (Agrilus planipennis) Density and Canopy Dieback in Three North American Ash Species Andrea C. Anulewicz, Deborah G. McCullough, and David L. Cappaert Abstract. Emerald ash borer (Agrilus planipennis Fairmaire) (Coleoptera: Buprestidae), a phloem-feeding insect native to Asia, was identified in 2002 as the cause of widespread ash (Fraxinus) mortality in southeast Michigan, U.S. and Windsor, Ontario, Canada. Little information about A. planipennis is available from its native range and it was not known whether this invasive pest would exhibit a preference for a particular North American ash species. We monitored A. planipennis density and canopy condition on green ash (F. pennsylvanica) and white ash (F. americana) street trees in four neighbor- hoods and on white and blue ash (F. quadrangulata) trees in two woodlots in southeast Michigan. Green ash street trees had significantly more canopy dieback and higher A. planipennis densities than white ash trees growing in the same neighborhood. Density increased by two- to fourfold in both species over a 3-year period. Canopy dieback increased linearly from 2002 to 2005 as A. planipennis density increased (R2 0.70). In each of the woodlots, A. planipennis densities were significantly higher on white ash trees than blue ash trees. Woodpecker predation occurred in all sites and accounted for 35% of the A. planipennis that developed on trees we surveyed. Results indicate that surveys for A. planipennis detection in areas with multiple ash species should focus on the relatively preferred species. Key Words. Blue ash; emerald ash borer; Fraxinus; green ash; host preference; insect survey; invasive pest; white ash; woodpecker. The emerald ash borer (Agrilus planipennis Fairmaire), an invasive buprestid, was identified in July 2002 as the cause of widespread ash (Fraxinus) mortality in southeast Michigan, U.S. and Windsor, Ontario, Canada (Cappaert et al. 2005c). Dozens of additional infestations have been found since 2003 in other areas of Michigan, Ohio, Indiana, Illinois, and Mary- land (www.emeraldashborer.info 2006). Agrilus planipennis is native to China, Korea, and other Asian countries (Yu 1992) but is not a major pest in its native range (Akiyama and Ohmomo 2000). It was likely introduced into North America through solid wood packing material (Cappaert et al. 2005c; Poland and McCullough 2006). In southeast Michigan, A. planipennis adult emergence be- gins in mid to late May (Brown-Rytlewski and Wilson 2005; Cappaert et al. 2005c). On emergence, beetles feed on ash foliage for 5 to 7 days before mating and another 5 to 7 days before females begin oviposition (Bauer et al. 2004; Lyons et al. 2004). Individual adult beetles live for 3 to 6 weeks and adult activity peaks from late June to early July (Cappaert et al. 2005c). Eggs laid in July and August hatch in ≈2 weeks (Lyons et al. 2004). Larvae feed on phloem for several weeks, often scoring the outer sapwood (McCullough and Katovich 2004; www.emeraldashborer.info 2006). Most A. planipennis overwinter as prepupal larvae in shallow chambers excavated ©2007 International Society of Arboriculture in the outer sapwood or in the bark of thick-barked trees. Recent evidence has shown that some larvae overwinter as early instars and complete their feeding during the second summer. The underlying cause of this extended development is not understood, but it seems to be most common in healthy trees with low densities of A. planipennis (Cappaert et al. 2005c). Woodpecker predation of prepupal larvae is common in many sites and occurs mostly during winter and early spring (Cappaert et al. 2005b; Lindell et al., unpublished data). Pupation begins in late April or May and adults emerge roughly 2 weeks later, leaving distinctive D-shaped exit holes, 3 to 4 mm (0.12 to 0.16 in) in diameter (McCullough and Katovich 2004). In North America, A. planipennis is aggressively attacking healthy, as well as stressed, ash trees. An estimated 20 mil- lion ash trees in southeast Michigan alone were dead or dying by late 2006. This invasive pest could potentially spread throughout North America through natural dispersal by adult beetles and artificial spread caused by humans moving in- fested ash material. In the United States, there are at least 16 native species of Fraxinus (Harlow et al. 1991) and more than 8 billion ash trees on forest land (FIA 2006). At least 800 million ash trees occur on timberlands in Michigan, including green ash (F. pennsylvanica), white ash (F. americana), black
September 2007
| Title Name |
Pages |
Delete |
Url |
| Empty |
Search Text Block
Page #page_num
#doc_title
Hi $receivername|$receiveremail,
$sendername|$senderemail wrote these comments for you:
$message
$sendername|$senderemail would like for you to view the following digital edition.
Please click on the page below to be directed to the digital edition:
$thumbnail$pagenum
$link$pagenum
Your form submission was a success. You will be contacted by Washington Gas with follow-up information regarding your request.
This process might take longer please wait
