RESPONSE OF EASTERN LARCH BEETLE (COLEOPTERA: SCOLYTIDAE) IN ALASKA TO ITS NATURAL ATTRACTANT AND TO DOUGLAS-FIR BEETLE PHEROMONES

Abstract

AbstractIn tests conducted in the McKinley River drainage, Alaska, seudenol combined with α-pinene attracted the most eastern larch beetles, Dendroctonus simplex LeConte. The next most attractive treatments included tamarack log sections infested with either unmated female D. simplex or unmated female Douglas-fir beetles, Dendroctonus pseudotsugae Hopkins, Neither frontalin nor trans- verbenol with α-pinene was attractive. Addition of niethylcyclohexenone (MCH) to the seudenol + α-pinene treatment repressed its attraction by 83%. Sex ratios of simplex responding to logs infested with female simplex or pseudotsugae were equal or favored females, but favored males in the case of seudenol + α-pinene. Addition of MCH shifted the sex ratio in favor of females. Two other scolytid species, Orthotomicus caelatus (Eichhoff) and Ips perturbatus (Eichhoff), were trapped, but were too few to relate to treatments. Two species of clerids were caught on traps: Thanasimus undatulus Say and Thanasimus dubius (L.); the latter is a new Alaskan record.