ENANTIOMERIC COMPOSITION AND RELEASE RATES OF EXO-BREVICOMIN INFLUENCE AGGREGATION OF THE WESTERN BALSAM BARK BEETLE, DRYOCOETES CONFUSUS SWAINE (COLEOPTERA, SCOLYTIDAE)

Field experiments demonstrated that the western balsam bark beetle, Dr yocoetes confusus, responded best to multiple-funnel traps baited with mixtures of (+)- and (-)-exo-brevicomin. (+/-)-exo-Brevicomin release d at 0.8 mg per 24 h performed as well as or better than release rates of from 0.2 to 1.0 mg per 24 h in terms of the number of baited trees which were mass attacked (80%), average attack density, and average n umber of trees attacked within a 10-m radius of baited trees. Baiting more than one tree in a spot resulted in an intensification of attack on baited trees and increased the number of trees attacked within 10 m of each spot.