Invertebrate species at risk from Ash Dieback in the UK

Abstract

Ash Dieback, a disease of Ash (Fraxinus excelsior) trees caused by the ascomycete, Hymenoscyphus pseudoalbidus, was first noticed in the UK in February 2012 and has since been found through much of the country. Evidence from elsewhere in Europe suggests that most infected Ash trees succumb to the disease and, hence, UK woodlands and landscapes are at risk of large scale changes. A wide range of taxa either depends on Ash or makes significant use of it and is likely to be detrimentally affected if the UK's Ash trees are seriously depleted. Invertebrate species that use Ash exclusively or are highly associated with the tree were identified from existing literature. We categorised 36 invertebrate species as ''obligate'' on Ash in the UK and a further 38 as ''highly associated''. Hemiptera, Diptera and Lepidoptera were the most significant groups amongst the obligate species with Coleoptera, Lepidoptera and Diptera dominating the highly associated species. Most obligate species are phytophagous in their use of Ash. Highly associated species were evenly split between those that are phytophagous and those classified as saproxylic with a smaller number of species employing a range of additional feeding strategies. Among highly associated species that are phytophagous, Privet (Ligustrum sp.) was the most frequent alternative plant used. This and other alternative trees and shrubs could be used to help mitigate the effects of Ash Dieback in limited localised situations, where rare species might be affected. Additional suggestions for managing the impact of Ash Dieback on invertebrates are discussed.

Ash dieback due toHymenoscyphus fraxineus: what can be learnt from evolutionary ecology?

“…In theory, emerging infectious diseases can lead to the extinction of host populations (McCallum, ). Thus, the wide range of the ash dieback outbreak is worrying, not only for F. excelsior (and F. angustifolia ), but also for the many organisms associated with ash trees (Ellis et al ., ; Heilmann‐Clausen et al ., ; Littlewood et al ., ) and the ecosystem services they provide (Pautasso et al ., ; Freer‐Smith & Webber, ; Mitchell et al ., ). Exotic, virulent tree pathogens such as H. fraxineus effectively act as agents of niche destruction, although the massive, one‐off production of deadwood is leading to niche construction for saproxylic organisms adapted to ash deadwood (Pautasso et al ., ).…”

Biological Flora of the British Isles:Fraxinus excelsior

“…; Lõhmus & Runnel ), insects (Littlewood et al . ) and fungi specific to F. excelsior (see IV (B) and IX(C)). More generally, Mitchell et al .…”

“…If the loss of ash due to ash dieback and the emerald ash borer becomes severe, which appears highly probable, this will cause large-scale change to many communities (see III) and many associated organisms will also decline (Pautasso et al 2013) including lichens (J€ onsson & Thor 2012;Ellis et al 2013;Lõhmus & Runnel 2014), insects (Littlewood et al 2015) and fungi specific to F. excelsior (see IV (B) and IX(C)). More generally, Mitchell et al (2014a) suggests that 1058 species are associated with ash or ash woodland including 12 birds, 55 mammals, 78 vascular plants, 58 bryophytes, 68 fungi, 239 invertebrates and 548 lichens species, many of which are threatened or endangered.…”

The susceptibility of Asian, European and North American Fraxinus species to the ash dieback pathogen Hymenoscyphus fraxineus reflects their phylogenetic history

“…With a history of around 20 years in Europe, common ash is now heavily affected by ash dieback throughout most of its natural range . Being a keystone species in European riparian forests, heavy losses of F. excelsior will have substantial effects on associated species (Jönsson and Thor 2012;Littlewood et al 2015;Lõhmus and Runnel 2014;Lygis et al 2014;Mitchell et al 2014;Pautasso et al 2013).…”