Pine Shoot Beetle (Tomicus piniperda (L.))

Forest Health Alert - Pine Shoot Beetle (Tomicus piniperda (L.))

 

Introduction

 

The pine shoot beetle is native to Europe, North Africa and Asia. It was first found in Ohio in 1992.

Pine Shoot Beetle
 
Adult beetles are 3-5 mm long, black or dark brown in color, cylindrical in shape


Subsequent surveys since then have found the insect in 26 counties in southern Ontario, several locations in Quebec and over 180 counties across 8 states in the northeastern United States. Although the pine shoot beetle was first found in Ontario in 1992, it has probably been present for 10 or more years.

 

Originally the pine shoot beetle was thought to be mostly a benign pest, causing limited damage to pines, primarily Scots pine. In 1998 the situation changed in Ontario; the pine shoot beetle was found to be attacking Scots pine and native pines in high numbers, resulting in tree mortality in several stands. Like many other introduced organisms it is thought to have arrived in North America through imports shipped using wooden crates, wooden pallets, or with logs used to brace loads. The Canadian Food Inspection Agency working in conjunction with the Canadian Forestry Service and the Ministry of Natural Resources are continuing surveys for this pest in Ontario.

 

The Threat

  • This pest attacks both healthy and stressed trees.
  • All native pines in Ontario are at risk, as well as Austrian, Scots and mugo pines.
  • Some current harvesting practices provide an excellent environment for this pest to reproduce.
  • No practical insecticide treatment exists.
  • The beetle attacks trees in 2 ways:
    • adults attack 1-3 year old healthy shoots by tunneling in the pith towards the tip, resulting in shoot death.
    • adults bore under the bark of the main stemof the tree, construct a brood chamber, mateand lay eggs. Developing larvae then feed on the cambium resulting in tree death by girdling.
  • if the insect expands its range it poses a serious threat to Ontario and Canada’s natural forest resource.

 

What to look for:

 

Eggs, larvae or puae located under the bank of stumps, slash, cut trees or on the main stems of stressed trees. Shoot damage is highest in the upper crown and the least in the lower crown of the tree.

Wilted, drooping, yellowing or fallen shoots
Wilted, droopoing, yellowing or fallen shoots
Pin head sized (2mm) exit holes and boring evidence on the main stems of the trees
Pin head sized (2mm) exit holes and boring evidence on the main stems of trees.
Adult beetles inside the shoots
Adult beetles inside the shoots
Shoots with resin encrusted borer holes
Shoots with Resin encrusted borer holes
Characteristic brood galleries under the bark
Characteristic brood galleries under the bark
Shoots with the pith cleanly bored out
Shoots with the pith cleanly bored out.

What it does:

 

The pine shoot beetle has the ability to cause whole tree mortality in only two years.
The pine shoot beetle can create its own brood material by first attacking the shoots of a healthy tree. This shoot attack stresses and weakens the tree, allowing the beetle to overcome the tree defenses and then breed in the main stem. This eventually results in the death of the tree. This demonstrated ability makes all stands of pine a potential candidate for attack by the pine shoot beetle.

 

Life Cycle

 

  • There is one generation per year.
  • Adults may overwinter in the fallen shoots in warmer climates, but generally spend the winter under bark scales at the base of the tree or in the soil where they are insulated by snow.
  • Adult beetles are 3-5 mm long, black or dark brown in color, cylindrical in shape.
    Adults search for brood sites during the first warm days of spring when day time high temperatures reach 10 - 12° C.
  • Adults may fly several kilometers in search of host material for breeding or shoot feeding.
  • Breeding sites are usually in freshly cut stumps, logs or slash, however living trees are also attacked. These trees may be stressed by insects or abiotic factors such as drought.
  • Females lay eggs in galleries constructed between the bark and the sapwood of the host tree.
  • Egg galleries are 10 - 25 cm long, eggs are 1mm long, oval and shiny white.
    Upon hatching, larvae feed in separate feeding galleries radiating from the original gallery made by the adult female beetle.
  • Approximately mid-June the larvae stop feeding, pupate and emerge as adults. Adults may lay eggs more than once in a season. These are called "sister broods".
  • The adults then chew a pin sized hole (2 mm) as they emerge from under the bark.
  • The beetles fly to the top of pine trees, attack shoots by boring into them, and feed in the pith as they tunnel towards the tip of the shoots.
  • Adults attack living pine trees of all sizes except seedlings.

 

History of invested areas

 

The pine shoot beetle was first thought to be only a pest of Scots pine Christmas trees or unhealthy plantations. In 1998, considerable damage, including tree mortality, was found to be occurring on Scots, red, white and jack pine in several counties in southwestern Ontario.

Damage caused by the Pine Shoot Beetle
Beetles emerge and attack native white pine

 

It is not known whether Scots pine must be present to enable pine shoot beetle to reach populations high enough to damage healthy trees of other pine species. Research is ongoing.

 

Some of the current harvesting practices used in Ontario may create a favorable environment for this pest to thrive. For example, pine slash left on site after harvests provides ideal brood material for the beetle.

 

Quarantines

 

The Canadian Food Inspection Agency (CFIA) has responsibility under the Plant Protection Act for introduced pests.

 

A quarantine has been imposed by CFIA on all known infested counties, restricting the movement out of these counties of: pine logs with bark attached, unprocessed bark, foliage, Christmas trees and nursery stock.

 

Under the North American Plant Protection Organization, comprised of Canada, United States and Mexico, CFIA intends to require that all imports use only dunnage, crating and packing material that is kiln dried, fumigated, or treated with insecticide. The intent is to reduce the risk of introducing pine shoot beetle and other pests.

 

What is Being DoneTree Mortality caused by the Pine Shoot Beetle

 

  • Beginning in 1998, the Ministry of Natural Resources carried out surveys for this pest to determine its severity.
  • Follow up work during the fall has also been carried out by the Ministry of Natural Resources to confirm damage to all species of pine.
  • Further surveys by CFIA, CFS, and MNR are expected to continue.
  • CFIA, and partners are reevaluating Pine Shoot Beetle management in light of the increased risk to natural pine forests.

 

How the Public Can Help

 

  • Report signs and symptoms of infested trees to the CFIA by phone 1 800 442-2342 (toll free) or online at www.inspection.gc.ca, or contact the OMNR at 1 800 667-1940 (toll free), or your local municipal parks or forestry department.
    Known Distribution in North America
    Known Distribution in North America
  • Manage for healthy trees and healthy forests. Follow best management practices for woodlots, and encourage a diversity of tree species.
  • All potential brood material should be removed from infested areas. These pine materials include:
    • recently cut stumps
    • cut trees with bark attached
    • branches over 5cm in diameter
    • stressed or dying trees
  • All material should be chipped, burned or buried under at least 30 cm of soil no later than May 31.

 

For more information on forest health issues, contact the Ontario Ministry of Natural Resources Information Centre at 1-800-667-1940