Dynamics of the Volatile Defense of Winter “Dormant” Balsam Poplar (Populus balsamifera)
Journal of Chemical Ecology
Clausen, T. P., Chen, J., Bryant, J. P., Provenza, F. D., & Villalba, J. (2010). Dynamics of the Volatile Defense of Winter “Dormant” Balsam Poplar (Populus balsamifera). Journal of Chemical Ecology, 36(5), 461-466. doi:10.1007/s10886-010-9788-0
6-Hydroxycylohex-2-en-1-one (6-HCH) has been reported as a major chemical defense of the winter-dormant internodes of balsam poplar (Populus balsamifera) against feeding by herbivores such as the snowshoe hare (Lepus americanus). We report that the concentration of 6-HCH in the fall internodes is triggered by a single hard frost, and then undergoes an exponential decline through volatilization over the winter that results in barely detectable quantities by early spring. We conclude that the role of 6-HCH in the defense of mature balsam poplar is more complex than simply acting as a toxin. Rather, 6-HCH’s role as a defensive agent must evolve over the course of the winter from being a co-toxin to a cue for a conditioned flavor aversion (CFA) to finally having no role by late spring.