Aggregation behaviour of the beetle Ips grandicollis in response to host-produced attractants.
This paper reports an investigation of host selection of an engraver beetle, Ips grandicollis (Eichh.). Males of Ips grandicollis initiated attacks in weakened trees in response to olfactory stimuli of the preferred host, Pinus taeda. These stimuli were volatile terpenes isolated from the host phloem. Geraniol, limonene, methyl chavicol, and myrcene were strong stimuli for males, and camphene was attractive to females. Alpha and beta pinene were less attractive to either. The heaviest male attacks were related to the greatest concentration of attractive terpenes. Host attractiveness was dependent on the qualitative and quantitative composition of terpenes, which were related to the physiological condition of the host.