Under Siege: Ash Management in the Wake of the Emerald Ash Borer
Total Page：16
File Type：pdf, Size：1020Kb
Journal of Integrated Pest Management, (2017) 9(1): 5; 1–16 doi: 10.1093/jipm/pmx029 Recommendations Under Siege: Ash Management in the Wake of the Emerald Ash Borer Houping Liu Pennsylvania Department of Conservation and Natural Resources, Bureau of Forestry, 400 Market Street, RCSOB, 6th Floor, P.O. Box 8552, Harrisburg, PA 17105–8552 ([email protected]) Subject Editor: Dr. Eric Rebek Received 24 April 2017; Editorial decision 27 October 2017 Abstract A conceptual framework designed to protect and preserve ash trees (Fraxinus spp.) from the emerald ash borer, Agrilus planipennis Fairemaire (Coleoptera: Buprestidae), at the community level was created in Pennsylvania in 2012. Advancements in the most recent Fraxinus systematics, taxonomy, distribution, and biogeography were reviewed. Description, biology, hosts, damage, invasion, spread, and potential impacts of A. planipennis were summarized. Ash resources at risk were identified, and pest status ofA. planipennis was evaluated. Current management strategies for A. planipennis (containment and eradication, host resistance, silviculture, chemical control, biological control, and slow ash mortality) were incorporated into the model plan. A template with step- by-step instructions was made available for communities to develop their own management plans by selecting from four management options (no action, selective management, preemptive management, and aggressive management) to fit their needs. Follow-up training and promotion of the model plan, coupled with technical support and financial assistance to participating communities resulted in 12 finished plans across the state, with more than 7,000 hazard trees removed, 5,000 trees treated, and 3,000 non-host trees planted. Case studies for three communities with implemented plans provided details to the plan development and execution process. The future of ash species and the direction of A. planipennis and ash management in North America are discussed. Key words: ash management, Fraxinus, emerald ash borer, community Ash trees (Fraxinus spp.) are commonly found in temperate and sub- northeastern China in the 1950s and 1960s (Zhang et al. 1995, Liu tropical regions from North America to Eurasia. Most of them are large et al. 2003). During the most recent outbreak in the late 1990s, thou- to medium-sized deciduous trees in their habitats, although there are a sands of velvet ash trees along streets and in urban parks were destroyed few evergreen shrubs and small trees adapted to arid environments (Wei in Tianjin City (Zhang et al. 1995). However, when EAB was acciden- and Green 1996). Ash are important timber species in many countries tally introduced to North America in 2002, it wreaked havoc in the where the wood is widely used for the manufacture of tool handles, Great Lakes region and Midwest and Northeast states. baseball bats, furniture, cabinetry, basketry, and solid wood packing This article examines management options for ash trees in the material (Stewart and Krajicek 1973). Cultivars of many ash species wake of EAB by 1) identifying ash resources at risk, 2) evaluating EAB are widely planted in urban communities for their aesthetic beauty and pest status, 3) introducing current management strategies, 4) sharing ability to thrive in those areas (MacFarlane and Meyer 2005). ash management plans from Pennsylvania, and 5) offering general The emerald ash borer (EAB), Agrilus planipennis Fairmaire conclusions and perspectives. Instead of managing EAB populations (Coleoptera: Buprestidae), is a woodboring beetle from northeast Asia over large areas, it is time to direct our limited resources to the pro- (China, Korea, Japan, and Russia’s Far East) (Yu 1992, Haack et al. tection of valuable individual trees and the conservation of the entire 2002, Xu 2003). Synonyms include Agrilus marcopoli Obenberger (in Fraxinus genus. This paradigm shift could have profound impact on China), A. marcopoli ulmi Korosawa (in Korea and Japan), and Agrilus the future directions of EAB/ash management programs nationwide. feretrius Obenberger (in Taiwan) (Jendek 1994). In the native range of EAB, it is generally considered a minor pest of ash species (Yu 1992; Liu Ash Species (Fraxinus spp.) et al. 2003, 2007; Wei et al. 2004; Baranchikov et al. 2008). Outbreaks are rare and only occurred when North American species such as white Systematics and Taxonomy (Fraxinus americana L.), green (Fraxinus pennsylvanica Marsh), and Ash is a group of flowering plants in the genus Fraxinus, one of velvet ash (Fraxinus velutina Torr.) were introduced into northern and the 24 extant genera in the olive family (Oleaceae). The genus was © The Author(s) 2018. Published by Oxford University Press on behalf of Entomological Society of America. This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/), 1 which permits non-commercial re-use, distribution, and reproduction in any medium, provided the original work is properly cited. For commercial re-use, please contact [email protected] Downloaded from https://academic.oup.com/jipm/article-abstract/9/1/5/4830135 by guest on 27 May 2018 2 Journal of Integrated Pest Management, 2017, Vol. 9, No. 1 described by Linnaeus in 1753. More than 450 described taxa Himalayan ash (Fraxinus griffithii C.B. Clarke) in east and southeast (mostly synonyms) have been described since then. Lingelsheim Asia, Chinese ash (Fraxinus chinensis Roxb.) in China, European ash (1920) included 64 species in his monograph, while Jeandroz (Fraxinus excelsior L.) in northern and central Europe to western et al. (1997) placed 34 species in five sections in their study based Russia, narrow-leaved ash (Fraxinus angustifolia Vahl) in southern on internal transcribed spacer sequences of nuclear ribosomal DNA. and central Europe to central Asia, and Manna ash (Fraxinus ornus In a systematic study on the genus, Wallander (2008) recognized 43 L.) in central and eastern Mediterranean. Those not mentioned are worldwide species in six sections (Dipetalae, Fraxinus, Melioides, more limited to certain areas with specific climatic and site condi- Ornus, Pauciflorae, and Sciadanthus) and one group of uncertain tions (Wallander 2008). placement (incertae sedis) (Table 1). This phylogeny of Fraxinus was Ash trees originated from North America in the Eocene (be- later adopted by Hinsinger et al. (2013) except for some differences tween 34 to 56 million years ago [mya]) (Call and Dilcher 1992, in the use of synonyms and the placement of Fraxinus platypoda Jeandroz et al. 1997, Besnard et al. 2009, Hinsinger et al. 2013). Oliv., Fraxinus cuspidata Torr., Fraxinus chiisanensis Nakai, and Dispersal between North America and Eurasia occurred during the Fraxinus spaethiana Lingelsh. Oligocene (between 23 to 34 mya) through a North Atlantic bridge Fraxinus is a monophyletic genus that is separated from others in (the Atlantic track) and the Beringia (the Pacific track) (Wallander the family by the large imparipinnate leaves and one-seeded samaras 2008, Hinsinger et al. 2013). Major events in the biogeographical (Wallander and Albert 2000). There is much variation in leaf morph- history of Fraxinus chronologically include: the appearance of the ology, including shape, size, texture, number of leaflets, and charac- genus in North America, early divergence of section Dipetalae, diver- teristics on leaf margin, petiolule, indumentums, epidermal papillae, sifications of sections Melioides and Pauciflorae, lineage migration rachis wings, etc. among different species. About one-third of the to Asia for the appearance of section Ornus and species F. platyp- ash species are entomophilous (insect pollinated) and two-thirds oda, expansion of section Sciadanthus in Eurasia and into Africa, are anemophilous (wind pollinated). Most anemophilous species divergence of Asian section Fraxinus, backward lineage migration are dioecious (having male and female flowers on separate plants) to North America for the appearance of F. nigra, differentiation of or polygamous (having male, female, and bisexual flowers on the F. mandshurica in Asia, and lineage expansion to Europe for the same plants). Most entomophilous species are androdioecious (both diversification of section Fraxinus though Eurasia (Jeandroz et al. bisexual and male flowers on the same plant), whereas a few are 1997, Wallander 2008, Hinsinger et al. 2013). hermaphrodites (both male and female flowers on the same plants). The ash flower is small with one pistil and two stamens. It may or may not contain a corolla and calyx. If present, the synsepalous EAB (A. planipennis Fairmarie) calyx is small, cup-shaped, and usually dentate, and the corolla is Description and Biology consisted of two or four white, linear and free petals. The petalifer- EAB adults (Fig. 1A) are metallic to coppery–green beetles in the ous flowers of the entomophilous species emerge with leaves from family Buprestidae. The body is slender and elongate, measuring 7 terminal buds in large showy panicles, while the apetalous flowers to 14 mm long. Eggs (Fig. 1B) are cream-colored initially, becom- of the anemophilous species occur before the leaves in lateral or ter- ing yellowish brown before hatching, oval, and measure 1.0 × minal inflorescences. There are four ovules in the syncarpous ovary, 0.6 mm (long axis × short axis). Larvae (Fig. 1 C–E) are white to although usually only one develops into a samara with one seed in- cream-colored and dorso-ventrally flattened with a mostly retracted side (Wallander 2008). brown head and a 10-segmented abdomen. The last abdominal segment has a pair of brown, pincer-like appendages (urogomphi). Distribution and Biogeography Pupae (Fig. 1F) are cream-colored and 7–14 mm long with visible Of the 43 recognized species of ash trees, 16 are found in the United appendages and a slightly curved abdomen (Yu 1992, Chamorro States, 4 in Mexico and Central America, 20 in eastern Asia, and 3 et al. 2012). Closely related species in the same family in North in Europe and western Asia (Table 1). White ash is a mesophytic America include the two-lined chestnut borer (A.