THE EFFECT OF CONSTITUTIVE RESISTANCE IN LODGEPOLE PINE (PINUS-CONTORTA) AND SCOTS PINE (PINUS-SYLVESTRIS) ON OVIPOSITION BY 3 PINE FEEDINGHERBIVORES

The acceptance of different provenances or seed origins of lodgepole p ine Pinus contorta and Scots pine P. sylvestris as suitable ovipositio n sites was found to vary as a function of both tree age and insect sp ecies. Experiments on seedling lodgepole pine revealed that the pine s awfly, Neodiprion sertifer Geoffroy (Hymenoptera: Diprionidae), and th e larch bud moth, Zeiraphera diniana Guennee (Lepidoptera: Tortricidae ), preferred more southerly provenances of lodgepole pine. The pine be auty moth, Panolis flammea Denis & Schiffermuller (Lepidoptera: Noctui dae), however, preferred more northerly provenances. On mature lodoepo le pine however, P. flammea exhibited a host change, preferring the mo re southerly provenances. Neodiprion sertifer showed a similar prefere nce on both seedling and mature provenances. The results of this study suggest that some provenances of lodgepole pine become more resistant to attack by P. flammea as they mature, while others become more susc eptible. This may be related to the feeding strategies of the two inse cts: P. flammea larvae feed on current year foliage while N. sertiJeu feeds only on previous year foliage. It is possible that the mechanism for chemical defence of new shoots changes as the trees mature, and t o a varying degree in different provenances, while defence of the prev ious years foliage remains unchanged. Results also indicate that odour alone as opposed to odour plus visual stimulation may invoke differen t ovipositional behaviour in N. sertifer.