English names: Northern Pine Weevil, Deodar Weevil
Nordic names: (DK),(FI), (NO), (SE)
Major host plants
P. nemorensis is a weevil pest to coniferous trees. It has a very wide host range within the species of Pinus, Picea and Cedrus.
Nursery plants less than 30 cm are killed by the larvae. Resin flow can be seen on older twigs. Removal of bark will reveal the pupal chip cocoons and cavities covered with long wood fibers of frass. Whole trees may be attacked, from the roots up to branches of more than 1.25 cm in diameter. Trees of up to 8 m may change their colour to a reddish-brown when adult weevils feed on the sap wood. Heavily infested trees may die or the crown may appear burnt and needles fall prematurely.
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P. nemorensis is native in North America, but it has probably been introduced to Russia, Japan and South Africa.
A map can be downloaded from EPPO´s website. See instructions here.
Adult weevils become active in fall. They feed and mate and females lay eggs in the holes made while feeding in the bark. Larvae emerge from the eggs and feed in the inner bark. The pupae occupy chambers (chip cocoons) made by the larvae. New adults emerge in spring. The length of the life cycle of P. nemorensis varies somewhat in the different climatic regions.
The natural spread of Pissodes spp. is determined by their flight ability which seems to be up to 100 km. International spread would most probably occur via the shipment of living conifer plants, including Christmas trees. P. nemorensis may attack all parts of the tree, so that there is a possibility of chip cocoons being present on or in wood below any remaining bark.
Detection and inspection
P. nemorensis is difficult to detect, because the pupae are concealed by chips. Cocoons are found below the bark on or in the surface of wood.
Pest status and importance
Trees of all ages are susceptible to weevil damage. Therefore, introduction of P. nemorensis could have severe economic and ecological impacts.
Source of information
See further information here:
Author: Elise T. Yamamoto Buch