The results of the first experiments with the tool done in a University of Illinois laboratory using leaves of wild parsnip (Pastinaca sativa) and hungry cabbage loopers (Trichoplusia ni) were published Jan. 15 on the online early edition of the Proceedings of the National Academy of Science.

Researchers found that damage to a leaf isnt relegated to a hole where tissue once was. In this case, it affects three to six times more of the leafs surface. The images gathered clearly recorded blue halos, representing damage to patches of cells surrounding the insect-caused holes, and varying levels of red fluorescence, denoting precise reductions in photosynthesis activity. They also found an almost 80-fold increase in the synthesis of furanocoumarins, a defensive chemical, suggesting that a plant may purposely turn down its photosynthetic machinery to boost its defensive capacity.

We dont know how our results will hold up in a real ecosystem, as weve only tested this instrument in a one plant-insect system under laboratory conditions, said Evan H. DeLucia, a UI professor of plant biology. But this study does suggest that we are greatly underestimating the impact of herbivores on plants. In the past, we knew tissue was removed. Now we know that the impact in terms of lost carbon gain can be much greater than just the tissue loss.

In a normal year, losses in agricultural and forest systems to dining insects range from 2 percent to 24 percent. The loss in plant photosynthesis, however, could be much greater and have potential management implications if carbon dioxide levels increase as projected under global warming scenarios. The device is now being tested on UI-gr
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Contact: Jim Barlow
b-james3@uiuc.edu
217-333-5802
University of Illinois at Urbana-Champaign
17-Jan-2002