A Defra Network partnership delivering interdisciplinary plant health FUTURE PROOFING research to improve biosecurity and build capability Plant Health Task 5.3. Preparing for pests and diseases Task 5.3.2. Management of Agrilus planipennis, the emerald ash borer Review of the Control and Management Strategies for Emerald Ash Borer (Agrilus planipennis) Rachel Down and Neil Audsley 31st March 2017 Work Package 5 Control Table of contents Abstract……………………………………………………………………………………………………………………………… 3 Chapter 1: Introduction (biology, host range, disperal)………………………………………………………. 4 Chapter 2: Surveillance, detection and monitoring.……………………………………………………………. 9 Chapter 3: Chemical control options…………………………………………………………………………………. 21 Chapter 4: Biological control (parasitoids)…………………………………………………………………………. 31 Chapter 5: Microbial control agents………………………………………………………………………………….. 48 Chapter 6: Lure and kill decoys……………………………………………………………………………………….... 53 Chapter 7: Quarantine treatment of wood packaging material and logs…………………………… 55 Chapter 8: Slow Ash Mortality (SLAM) for emerald ash borer management……………………… 56 Chapter 9: Case study - Emerald ash borer in the U.S.A. and Canada....……………………………. 66 Chapter 10: Emerald ash borer in Europe and European Russia..……………………………………… 74 Chapter 11: UK contingency plans……………………………………………………………………………………. 77 Conclusions……………………………………………………………………………………………………………………… 81 Recommendations…………………………………………………………………………………………………………… 84 References………………………………………………………………………………………………………………………. 87 Control and management strategies for emerald ash borer ∣ March 2017 Page 2 Abstract Emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), is a highly destructive insect that attacks and kills Fraxinus species of ash trees. In its native range in Asia emerald ash borer is only a sporadic pest, mainly attacking non native Fraxinus species, leaving the native species of ash unharmed unless already stressed by other factors. In 2002, the beetle was discovered in Michigan (U.S.A.) and Ontario (Canada), and has rapidly spread. In 2007 it was also discovered in Moscow (European Russia). In all instances the beetle was established, with increasing populations, upon discovery and was thought to have been present, but undetected, for several years. In these invaded areas, the native species of ash are highly susceptible to emerald ash borer, presumably because they have not co-evolved with the insect and built up resistance as a result. When emerald ash borer was first discovered in North America there was very little information available about the pest. Regulatory agencies and scientists were fully aware that if the spread of the pest was to be contained and managed, research would be required to understand its biology, interactions with host plants and natural enemies, and control and management strategies would need to be evaluated. This review details the research that has been conducted since 2002 in order to develop methods to help with detection, monitoring, management and control of the pest. Personnel in North America quickly realised that the beetle was too established and widespread to make eradication possible, and so in both the U.S.A. and Canada, management now focusses on slowing the rate of spread using a variety of methods determined according to factors specific to each outbreak site. These methods are continually being developed and improved. A range of methods for detection and monitoring of the beetle are available, all with their own advantages and disadvantages. Current methods for suppression of the pest include chemical control (considered appropriate for urban and sub-urban areas) and the use of non-native parasitoid wasps, originally found in China and the Russian Far East, and released into the U.S.A. as part of a classical biological control programme (considered more appropriate in rural and forested areas). In addition, new methods are continually coming onto the scene, for example, decoys capable of attracting beetles and then delivering an electric shock to kill them. In European Russia the story is very different. There are no official control measures in place because emerald ash borer is not a regulated pest in Russia. This therefore poses a serious concern to the remainder of Europe, which has a continuous distribution of European ash (Fraxinus excelsior L.) throughout. European ash is known to be susceptible to the pest, and as such emerald ash borer is a very serious threat to ash trees throughout Europe. At its current rate of spread it is estimated that emerald ash borer will reach the Russian/Belarus border around 2020, although of course it could enter Europe via human-assisted dispersal at any location and point in time beforehand. It is therefore advised that European countries have robust strategies and contingency plans in place such that if an outbreak was detected, management strategies can be quickly implemented. Control and management strategies for emerald ash borer ∣ March 2017 Page 3 Chapter 1: Introduction (biology, host range and dispersal) The Emerald ash borer (EAB; Agrilus planipennis Fairmaire (Coleoptera: Buprestidae)) is a xylophagous woodboring insect that attacks and kills ash trees belonging to the Fraxinus species of the Oleaceae family (Poland et al., 2015). It is a native species of Asian countries, including northeastern China, Japan, Korea, Mongolia, Taiwan and Eastern Russia (Cappaert et al., 2005; Haack et al., 2002; Poland et al., 2015). Agrilus planipennis has several synonyms including A. marcopoli Obenberger (1930; type China), A. marcopoli ulmi Kurosawa (1956; type Japan) and A. feretrius Obenberger (1936; type Taiwan) (Haack et al., 2002). In its native range emerald ash borer is generally only considered to be a sporadic pest. However, in North America, Canada and European Russia, where the emerald ash borer is an invasive species, it is a devastating pest responsible for the destruction of tens of millions of ash trees resulting in hundreds of millions of dollars of economic losses in the U.S.A. (Kovacs et al., 2010; Emerald Ash Borer Information Network, 2017). Biology of emerald ash borer Adult emerald ash borer emerge in spring (late May – early June depending on location) by chewing D-shaped exit holes (2-4 mm; Straw et al., 2013; Herms and McCullough, 2014). It has been suggested that growing degree day accumulations of 450-550 days (McCullough et al., 2011a; Herms et al., 2014), based on a threshold of 10°C and starting date of 1st January, are required for emergence. Adults are most abundant after 1000 growing degree days (Herms et al., 2014). In contrast, Brown-Rytlewski and Wilson (2005) recorded the start of emergence between 348-584 growing degree days, with peak emergence between 572-1027 growing degree days (all based on a threshold of 10°C) in Michigan, U.S.A. depending on year and location. In 2004 they also noted a second wave of emergence later in the year (mid-August to early September). These data would suggest that other factors may influence the timing of emergence. The adult beetles feed on the leaves causing crenulation to the edges, but do not cause significant damage to the canopy (Smitley et al., 2010a). The emerald ash borer lifecycle in Michigan, U.S.A. has been documented as follows. Adults live for three to six weeks, and are most active from late June to early July (Cappaert et al., 2005; Herms and McCullough, 2014; Poland et al., 2015, 2016). Reports on timing of mating and oviposition vary. Herms et al. (2014) and Herms and McCullough (2014) both report that they mate after five to seven days of feeding and females oviposit after feeding a further five to seven days, whereas McCullough et al. (2011a) suggests that they mate after seven days and start to oviposit 10-14 days later. Multiple matings can occur (Lyons et al., 2004). The eggs are laid individually in crevices on the bark and sometimes under bark flaps (Herms and McCullough, 2014); initially they are cream in colour but deepen to a reddish brown after a few days (Bauer et al., 2004a; Cappaert et al., 2005). In laboratory conditions the females typically lay 60-90 eggs, although up to 258 eggs during the course of a six week life span has been observed (Lyons et al. 2004; Cappaert et al., 2005). In the field, females typically lay 40-80 eggs (Herms and McCullough, 2014; Poland et al., 2015). Egg hatch occurs in late July/early August after about two weeks (Herms and McCullough, 2014). Larvae grow rapidly, passing through four larval stadia, tunnelling through the cambium layer under the bark, feeding on the phloem and scarring the xylem, resulting in tree girdling, and therefore inhibiting the flow of water and nutrients through the tree (Cappaert et al., 2005; Smitley et al., 2010a; Herms and McCullough, 2014; Poland et al., 2015). Tunnelling leads to Control and management strategies for emerald ash borer ∣ March 2017 Page 4 the creation of characteristic serpentine galleries (Herms and McCullough, 2014; Poland et al., 2015). Around October/November the larvae stop feeding and excavate a 1 cm deep cell in the sapwood or outer bark and overwinter as prepupal larvae (Cappaert et al., 2005; Herms and McCullough, 2014; Poland et al., 2015). Pupation begins in mid-April and lasts for approximately 3 weeks after which the adults emerge (Cappaert et al., 2005; Herms and McCullough, 2014; Poland et al., 2015). Usually emerald ash borer has a one year life cycle (univoltine) but in some instances two years are required for its development (bivoltine);