The beginning of the 21st century has seen an unprecedented assault on the UK by invasive forest pests and diseases (Defra 2013; Figure 1). Some of these new pests and diseases have attracted much media attention and have increased political awareness, e.g. the large scale death of larch caused by Phytophothora ramorum and ash dieback caused by Chalara fraxinea. In this article, however, I will concentrate on the insect threats to our forest landscape, both amenity and commercial, and suggest some possible solutions to the problem.
Exotic and invasive pests
Exotic and invasive insects are not a new phenomenon in the UK; the European spruce sawfly Gilpinia hercyniae was first recorded here in 1906, the Douglas fir woolly aphid (Adelges cooleyi) and the fir seed wasp (Megastigmus spermotrophus) since at least the late 1940s, the large larch bark beetle (Ips cembrae) since at least 1955 and the great spruce bark beetle (Dendroctonus micans) since at least 1973 (Crooke & Bevan, 1957; Bevan 1987). Apart from the last pest, none of these insects has however, had landscape level effects or caused huge public disquiet, although they have had sporadically serious implications for the UK forest industry.
Since the beginning of the current century, the situation has changed dramatically, the influx of tree pathogens has continued to rise at an almost exponential rate and the number of potentially landscape damaging insect pests has also seen an increase e.g. the horse chestnut leaf miner (Cameraria ohridella), first seen in London in 2002 (Straw & Williams, 2013), and now rampaging as far north as the Lake District and Newcastle-upon-Tyne the pine tree lappet moth (Dendrolimus pini) established in Scotland since 2004, the oak processionary moth (Thaumetopoea processionea) firmly established in London since at least 2006 and looking set to spread further north and west (Townsend, 2013), and the Asian longhorn beetle (Anoplophora glabripennis) an outbreak of which was found in 2012 in Kent.
This is an abstract of the full article published in: Outlooks on Pest Management – February 2014 issue.
Author: Simon leather, Director of the Harper Adams Centre for Integrated Pest Management. Department of Crop and Environment Sciences, Harper Adams University, UK.