The Asian long-horned Beetle (ALB) originates from Japan, Korea and China. They are wood-boring beetles, with the females chewing a hole into the bark of the tree and then laying a single egg into the hole. Larval development can last between 10 to 22 months, depending on climatic conditions and the time of year that the egg was laid. The larvae bore into the tree, creating tunnels that can affect the vascular functioning of the tree. This disruption in vascular flow weakens the tree and can lead to tree death. There are several symptoms of infested trees, including holes on branches and the trunk, sap emerging from the holes, sawdust (or frass) on branches and at the base of the tree. However, most of these symptoms occur at least 1.5 m above ground level and upwards towards the crown.
This makes initial symptoms harder to spot. The beetle infests a variety of hardwood trees, such as ash, maple, chestnut, birch and willow and once established the beetle is very hard to control.
It is a quarantine pest for Europe and was found in various parts of North America (New York, Chicago, New Jersey, Ontario) in 1996. Since then, quarantine zones have been set up around infested areas to contain the beetle, but they have been discovered in warehouses in the USA and Canada (http://www.uvm.edu/albeetle/) as well as Europe. ALB
has been found regularly in North America in imported wood and in wooden packaging, but there had only been five outbreaks until 2008 (Smith and Wu 2008).
16.1.1 Ea rly Era dica tion Cos ts
An outbreak on four trees in northern Italy, with only one adult beetle, caused the four infested trees to be cut down and destroyed along with uninfested trees of susceptible species (genera Acer, Betula, Salix and Populus) within a 500 m radius of the infestation. A total of 309 trees were destroyed. In addition to these clearance measures, the area was replanted with trees from non-susceptible species together with six sentinel trees. This area is thoroughly inspected periodically and will continue to be inspected until no sign of ALB has been detected for four years (Herard et al. 2009). The cost of removal of the 309 trees is estimated at £10,000 and the cost of 309 replacement and 6 sentinel trees, at £30 each, plus ten days labour for planting them at £250 a day. Surveillance was carried out six times per year for a period of 2 days, for 4 years i.e. 48 days. At an estimated cost of £250 per day surveillance costs therefore amount to £12,000. Despite efforts to contact those involved, details about the financial cost of the Italian outbreak could not be obtained. Hence, this figure does not include the cost of compensation for landowners, and the cost of removal and replanting are approximate estimates. Despite those limitations, the estimated cost for this very small outbreak is £33,950, indicating how even limited infestations can have large associated costs.
16.1.2 Wide s pre a d Era dica tion Cos ts
Fera has reported that environmental conditions in most of England and Wales as well as warmer coastal regions in Scotland would allow the establishment and breeding of this beetle. According to American research, the beetles are very resistant to cold temperatures, being able to tolerate -25.8 °C (Roden et al. 2008). It is therefore anticipated that the Asian long-horned beetle could potentially become established throughout Great Britain, with an associated increase in damage that would be very widespread and costly if initial outbreaks are not sufficiently contained.
Current control costs within the USA provide an indication of likely costs. Eradication attempts rely on the removal and destruction of infested trees and ‘high risk’ trees within a certain radius. Transport of woody material out of this area is banned and prophylactic treatment of at risk trees with systemic insecticides is carried out. An encapsulated contact insecticide is also used against adult beetles. Estimated costs provided by the US
Government Accountability Office associated with invasive populations of ALB include costs of eradication and costs resulting from the loss of tree cover. The Animal and Plant Health Inspection Service (APHIS) estimated the costs of eradication from 1998 to 2006 at $249 million (2006) (£18.7 million per annum), including the costs for survey and detection, tree removal, public outreach, and preventive treatment of landscape trees (Smith et al. 2009). A 1996 infestation in New York State cost more than $4 million (USDA 199884), and by December 2007 over 400,000 trees had been removed and over 97,000 trees treated in an attempt to eradicate this beetle.
If the beetle did become established in Great Britain, eradication would pose huge challenges, partly due to its biological nature and the difficulties in identifying infested trees when most of the signs of infestation are found above 1.5 m from the ground towards the crown of the tree. However, it is assumed that all hardwood forests could become infested, as well as trees found in gardens, parks and hedgerows. It is likely that similar methods would be used to eradicate the species as are currently used to control it in the USA and Italy.
There are 1,191,000 ha of hardwood forest in Great Britain. If it is assumed that for one infested tree, all trees within a radius of 500 m are to be felled, this corresponds to an area of 78.5 ha. The quantity of timber, hence the value of the crop, varies among tree species, but it is assumed for this calculation that the hardwood yield per ha is an average of the yield for oak, birch and beech (155 m3 ha-1) and the current average timber value is £28.5 m-3. Felling 78.5 ha of forest to contain a single infestation with ALB would consequently cost about £346,774, or £4,417.5 per ha worth of lost timber crop. It is assumed for this calculation that the market value of timber is such that it includes, felling, management, replanting and profit. Using these assumptions and assuming that 25% of the hardwood forests are infested, the cost of a widespread infestation could cost England £843,743,107, Scotland £331,312,739 and Wales £141,360,102. Therefore if ALB became established in Britain it could cost an £1,316,415,948 to eradicate the species (if it was actually possible).
This figure does not include the cost of eradication from other habitats, such as parks and gardens or hedgerows, so the cost of eradication could be even higher.
Each year, about 0.15 million m3
84www.aphis.usda.gov/oa/alb/
of sawn hardwood is produced in the UK, approximately 0.43% of the annual US hardwood production. The cost of the beetle to the US hardwood industry, if uncontrolled, has been estimated as $138 billion (Meyer 1998). Therefore, if ALB
became established in the UK, it could cost an estimated £434.69 million today to the forestry industry alone, based on the assumption that the cost of ALB is similar per unit of wood produced in Britain and USA. The calculated estimate is higher but it is assumed that the species would be eradicated by felling all infested trees and the trees surrounding them, which is costlier than accounting for the loss of crop only.