Insects on lodgepole pine in Sweden - current knowledge and potential risks

Eighty species of forest insects have thus far been recorded feeding on lod gepole pine in the Nordic countries (61 in Sweden). The list includes speci es that have Scots pine as their main host and which feed on needles, flowe rs, cones, and shoots, as well as species boring in the phloem and xylem of dead or dying Norway spruce. Contrary to our expectations, most of the ins ect species that have colonised lodgepole pine in Sweden can be considered specialists (with regard to host plant range and feeding mode) rather than generalists. We suggest that the current dominance of specialised insect he rbivores is related to the similarity in chemistry and morphology between l odgepole and Scots pine. Only a few of the species considered to be pests have caused considerable d amage in lodgepole pine stands in the Nordic countries. The most severe dam age has been caused by the needle feeders Neodiprion sertifer and Anthonomu s phyllocola. Hylobius abietis, the most harmful forest insect species in S candinavia, attacks lodgepole pine seedlings to about the same degree as it attacks Scots pine and Norway spruce and causes similar levels of mortalit y. Other pest species reported to have caused considerable damage to lodgep ole pine are Pissodes validirostris (cones) and Rhyacionia boulliana (shoot s). No insect species native to North America and living on lodgepole pine have yet to become established in the Nordic countries since the introduction o f this exotic tree species. The risk of large-scale damage in Sweden is dis cussed in relation to the distribution and management of lodgepole pine. (C ) 2001 Elsevier Science B.V. All rights reserved.