European spruce bark beetle
- Order: Coleoptera
- Family: Curculionidae
- Latin: Ips typographus L.
- English: European spruce bark beetle
- French: Typographe européen de l'épinette
Vector of Ceratocystis polonica Siemaszko.
This disease is dealt with in a number of Canadian Food Inspection Agency directives:
- D-98-08: Entry Requirements for Wood Packaging Materials Produced in All Areas Other than the Continental United States
- D-01-12: Phytosanitary Requirements for the Importation and Domestic Movement of Firewood
- D-02-12: Import requirements of non-manufactured wood and other non-propagative wood products, except solid wood packaging material, from all areas other than the continental United States
Since neither the insect (Ips typographus L.) nor the bluestain fungus (Ophiostoma polonicum) is present in Canada, the purpose of the primary measures implemented in Canada is to keep these pests from establishing here. Wood imports are regulated under Directive D-02-0-12 administered by the Plant Health Division of the Canadian Food Inspection Agency (http://www.inspection.gc.ca/english/plaveg/protect/dir/d-02-12e.shtml). Traps can be installed around locations where wooden dunnage is present to monitor areas at risk and to capture any bark beetles that may have been transported into Canada on this wood. Wood-boring insects often act as vectors of fungal pathogens. The European spruce bark beetle is the primary vector of Ophiostoma polonicum Siemaszko (Ceratocystis polonica), one of the most virulent bluestain fungi known to attack spruce species. Inoculation studies have shown that, in addition to Norway spruce, the following native spruce species are susceptible: Picea sitchensis, Picea glauca and Picea mariana (Nappo 2005).Ophiostoma polonicum is so virulent that it is capable of slowing diameter growth within a few weeks after it infects a tree—a rare ability among bluestain fungi. The lesions it causes deprive the tree of resources, causing the foliage to wilt (about 15 weeks after mass inoculation) and tree tissues to dry out, which eventually leads to mortality. The bark beetle–O. polonicum complex is a lethal combination for Norway spruce, and it is easy to understand the efforts devoted to managing this threat in Europe.The control measures described here are those applied in Europe to mitigate the impact of the European spruce bark beetle.
1. Mechanical and silvicultural
Bark beetle outbreaks are often associated with extreme weather conditions, such as windstorms and drought, which are beyond human control. Nonetheless, certain management measures can be implemented to reduce the bark beetle population and the subsequent damage level (Bakke 1989). Sanitation felling of infested trees before a new generation of beetles emerges is one way to keep the Ips typographus population in check. The cut logs cannot be left on the harvest site, however, which complicates matters. The infested timber should be buried or burned. Bark beetles are attracted to trees killed in windthrow events. Timely removal of windthrown timber is essential; ideally the wood should be removed after the infestation associated with the spring flight of the beetles but before the emergence of the summer broods (Wermelinger 2004). This allows the infested logs to act as “trap trees”.
Trap trees are trees that are wilfully killed to attract bark beetles in search of egg-laying sites. A tree selected for this purpose is either treated with a herbicide that causes drying of the tissues or the tree is girdled by making incisions around the stem or simply cut down. Between the time the bark beetles infest the trap tree to lay their eggs and the emergence of the new generation, the tree will be cut down, if not already done and destroyed. Because bark beetles are more attracted to dying trees than healthy ones, the trap tree method can reduce bark beetle numbers substantially. Ips typographus outbreaks tend to be smaller in heterogeneous stands in which spruce is not a major component (Wermelinger 2004). Monitoring should be stepped up during periods of weather unfavourable for spruce, such as drought and storms (Wermelinger 2004). In addition, all forest management interventions should be aimed at increasing the vigour of the stand.
Trapping is widely used as a control measure for the European spruce bark beetle. Various traps and baits are available commercially. The traps are baited with sex pheromones in order to attract bark beetles. However, their real efficacy depends on several factors, including the location of the device and local environmental conditions. Although traps have limited effectiveness in reducing bark beetle populations, they are useful for monitoring fragile stands and for drawing bark beetles away from living trees, thus limiting their reproduction. Traps can be used for prevention by creating a barrier of traps that will slow the advance of an infestation front (Wermelinger 2004).
Trap trees treated with pheromones and insecticides are much more efficient than artificial traps (Wermelinger 2004). Sacrificing lower-value trees can help to protect the rest of the stand.
Insecticide registered for use against the European spruce bark beetle in Canada: none
Insecticide registered for use against the pest in Europe: deltamethrin
If an infestation of European spruce bark beetles is detected, the forest manager should quickly determine whether any products (e.g., chlorpyrifos or azadirachtin) registered for use against other exotic insects can be used.
According to Warzée and Grégoire (2003), the coleopteran Thanasimus formicarius (L.) is a major predator of bark beetles. It has a flight period lasting more than four months, in Wallonia (Belgium) at least, which coincides with the emergence over time of several bark beetle species. It can serve as a control agent, supplementing mechanical and silvicultural measures and even chemical control.
5. Stages in an integrated disease management program
An integrated management program can only be implemented when the infestation is below the epidemic level. Here is the program recommended by Abgrall and Soutrenon (1991):
- For prevention purposes, systematically remove all weakened or dying spruces; avoid leaving cut timber and logging debris on cutovers; and remove windthrown timber. Commercial synthetic pheromone lures for European spruce bark beetles can be used in forests to monitor beetle populations.
- As soon as an Ips typographus infestation is detected, action must be taken to fell and debark affected trees. During the risk period, from May to October, this must be done within six weeks after harvesting. Treatments should be carried out simultaneously: deltamethrin can be sprayed on the bark and logging residues (for Europe) or this material can be burned.
- If major infestations are present, the trap tree method is recommended. A dozen trees are sacrificed per hectare each year, at a rate of two stems per hectare each month, repeated every two months. The trap trees should be debarked, burned or treated with chemicals only after the following are observed: entrance holes, signs of egg laying or the start of larval development. Synthetic pheromones can be used to enhance and simplify the trap tree technique by eliminating the need for debarking. The trap trees are treated with insecticide and then a pheromone dispenser is attached to them: any adult beetles that try to penetrate the bark will be killed.
- The cut timber should be removed from the forest within the prescribed time frames to prevent the bark beetles from completing their life cycle. This should be done before mid-March to mid-June, depending on the region, for logging done between October and May of the previous year. The wood should be removed at most six weeks after harvesting during the risk period, from May to October (Anonymous 2004).
- This material should be stored at a sufficient distance (at least 5 km) from forested areas, or it should be processed within a short time period.
- [Anonyme]. 2004. Lutte contre le typographe 2004. Département de la santé des forêts juin 2004, http://www.forestpests.org/france/LuttetypographeA4.pdf Consulté le 26 janvier 2009
- Abgrall, J.F. et A. Soutrenon. 1991 La forêt et ses ennemis, 3ième édition. CEMAGREF Grenoble pp. 191-194.
- Bakke, A. 1989. The Recent Ips typographus Outbreak in Norway: Experiences from a Control Program. Holarctic Ecology 12(4): 515-519.
- Humphreys, N., and Allen, E. 1999. Eight-spined spruce bark beetle - Ips typographus. Exotic Forest Pest Advisory Pacific Forestry Centre, Canadia Forest Service(3): 4.
- North American Plant Protection Organisation. 2005. Nappo phytosanitary alert system - Ceratocystis species. http://www.pestalert.org/viewNewsAlert.cfm?naid=1 consulté le 26 janv.-09
- Warzée, N. et Grégoire, J.C. 2003. Le cas exemplaire de Thanasimus formicarius L. Forêt Wallonne no 66. http://homepages.ulb.ac.be/~nwarzee/FW66_02-06.pdf Consulté le 26 janvier 2009
- Wermelinger, B. 2004. Ecology and management of the spruce bark beetle Ips typographus - a review of recent research. For. Ecol. Manag. 202: 67-82.
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