With only very few exceptions, plants emit green leaf volatiles (GLVs) when damaged. The GLVs released by damaged wild tobacco attract Geocoris bugs which attack herbivores, most importantly young herbivorous Manduca larvae: each Manduca larva, if allowed to grow to full size, can consume multiple full-grown wild tobacco plants! The emission of specific GLVs, including (E)-2-hexenal and related compounds, increases as soon as freshly hatched Manduca larvae start feeding on leaves and so Geocoris can tell whether the GLVs come from Manduca feeding as opposed to any other damage. In contrast, proteinase inhibitors (PIs) are synthesized in the leaves to interfere with the digestion of leaf proteins and thus render the plant less nutritious to herbivores; hence, they can weaken feeding caterpillars. Both GLVs and PIs have been shown to reduce the number of particular herbivores, or the amount of damage they cause, for plants growing in nature over the course of short field trials. This time, researchers asked the question: do these compounds increase yield, i.e. reproduction, over the full growing season of a plant? In other words, are plants which produce these compounds really fitter than those that don't?
In the summers of 2010 and 2011, Meredith Schuman, Kathleen Barthel and Ian Baldwin performed field experiments with
|Contact: Ian T. Baldwin|
Max Planck Institute for Chemical Ecology