The leaves of some birch trees may help deter herbivory by adsorbing arthropod-repelling chemical compounds emitted from neighboring plants.

“Plant-emitted semi-volatile compounds have low vaporization rates at
20–25°C and may therefore persist on surfaces such as plant foliage. The
passive adsorption of arthropod-repellent semi-volatiles to
neighbouring foliage could convey associational resistance, whereby a
plant’s neighbours reduce damage caused by herbivores.

“We found that birch (Betula spp.) leaves adsorb
and re-release the specific arthropod-repelling C15
semi-volatiles ledene, ledol and palustrol produced by Rhododendron
when grown in mixed association in a field setup

“In assessments for associational resistance, we found that
the polyphagous green leaf weevils (Polydrusus flavipes)
and autumnal moth (Epirrita autumnata) larvae
both preferred B. pendula to R.
. P. flavipes also preferred
birch leaves not exposed to R. tomentosum to
leaves from mixed associations. In the field, a reduction in Euceraphis betulae aphid density occurred in mixed

“Our results suggest that plant/tree species may be protected by
semi-volatile compounds emitted by a more herbivore-resistant
heterospecific neighbour.” (Himanen et al. 2010:722)

Last Updated August 28, 2020