IPSDIENOL AND LANIERONE INCREASE IPS PINI SAY (COLEOPTERA: SCOLYTIDAE) ATTACK AND BROOD DENSITY IN LODGEPOLE PINE INFESTED BY MOUNTAIN PINE BEETLE

Abstract

AbstractAttack and emergence of the engraver beetles Ips pini Say and I. latidens LeConte were measured in lodgepole pine (Pinus contorta var. latifolia Engelm.) naturally attacked by the mountain pine beetle, Dendroctonus ponderosae Hopk., in 1991. Sample trees were baited with the Ips pheromones ipsdienol and lanierone 1 week and 3 weeks after attack by the mountain pine beetle and again the following spring to observe the effects of the timing of bait placement. The densities of attack, egg gallery length, emergence, and hibernation of Ips species were measured. Ips latidens did not attack either the baited or unbaked trees at breast height until the spring of 1992 and the relatively low emergence was not significantly different by treatments. Among the 1991 treatments, the densities at breast height (1.3 m) of I. pini attack, egg gallery length, adult emergence in the fall of 1991, and numbers of hibernating adults in the duff were all highest for the 3-week treatment and lowest for the unbaked treatment. Significantly higher densities of beetles emerged and hibernated in the duff on the north sides of trees. Ips pini emergence in late summer 1992 from trees additionally baited in spring 1992 was significantly higher than for trees baited only in fall 1991. The density and temporal distribution of the emergence of both Ips species is discussed in relation to that of the mountain pine beetle.