Comparative white-pine weevil attack susceptibility and cortical monoterpene composition of western and eastern white pines

Cortical monoterpene composition of western white pine (Pinus monticola Douglas) and eastern white pine (Pinus strobus L.) was examined to interpret differential susceptibilities to white-pine weevil (Pissodes strobi (Peck)) attack. Concentrations of 7 of the 8 monoterpenes detected differed significantly between samples of the two species growing in the same plantation. Higher concentrations of beta -pinene and lower concentrations of camphene found in western white pine were the only differences between the two species that were consistent with differences reported by others. Concentrations of alpha -pinene and limonene in the more resistant species, western white pine, were similar to those previously found in the most susceptible eastern white pine individuals. It is unlikely that any of the individual cortical monoterpenes studied is the primary factor responsible for the differences in weevil attack susceptibility of the two species.