SEMIOCHEMICAL-BASED COMMUNICATION IN INTERSPECIFIC INTERACTIONS BETWEEN IPS-PINI (SAY) AND PITYOGENES-KNECHTELI (SWAINE) (COLEOPTERA, SCOLYTIDAE) IN LODGEPOLE PINE

The pine engraver, Ips pini Say, and Pityogenes knechteli Swaine often co-exist in lodgepole pine, pinus contorta var. latifolia Engelmann. We tested the hypotheses that P. knechteli produces an attractive pher omone and that the attraction of P. knechteli and I. pini to conspecif ics is inhibited by die presence of the other species. Pityogenes knec hteli males and females were attracted to bolts infested with conspeci fic males and to bolts infested with I. pini males; however, there was no significant cross-attraction of I. pini males or females to bolts infested with P. knechteli males. Attraction of P. knechteli and I. pi ni males and females to bolts infested with conspecific males was not inhibited in the presence of bolts infested with males of the other ba rk beetle species. Pityogenes knechteli has no potential for competiti ve displacement of I. pini but may enhance the adverse effect of I. pi ni on the mountain pine beetle, Dendroctonus ponderosae Hopkins.