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J Chem Ecol

Title:		Quantitative variability of direct chemical defense in primary and secondary leaves of lima bean (Phaseolus lunatus) and consequences for a natural herbivore
Author(s):		Ballhorn DJ; Schiwy S; Jensen M; Heil M;
Address:		"Department of Botany, University of Duisburg-Essen, Universitatsstr. 5, 45117, Essen, Germany. daniel.ballhorn@uni-due.de"
Journal Title:		J Chem Ecol
Year:		2008
Volume:		20080830
Issue:		10
Page Number:		1298 - 1301
DOI:		10.1007/s10886-008-9540-1
ISSN/ISBN:		0098-0331 (Print) 0098-0331 (Linking)
Abstract:		"Ontogenetic variability in chemical plant defenses against herbivores is a common phenomenon, but the effects of this variability on herbivore-plant interactions are little understood. In a previous study on lima bean (Phaseolus lunatus), we found a trade-off between cyanogenesis, a direct defense, and the release of herbivore-induced volatile organic compounds (VOCs; mainly functioning as an indirect defense). Moreover, the expression of these two defenses could change during plant ontogeny. The present study aimed at elucidating whether such ontogenetic changes in plant defense can affect herbivore-plant interactions. We quantified feeding rates of a natural insect herbivore, the Mexican bean beetle (Epilachna varivestis), on primary and secondary leaves of individual lima bean plants. These insects strongly preferred low cyanogenic primary leaves over high cyanogenic secondary leaves. Although weakly defended by cyanogenesis, lima beans' primary leaves showed protein concentrations and photosynthetic activities that did not differ significantly from secondary leaves at the time of analysis. Based on our findings, we suggest that lima beans' long-lived primary leaves function as efficient source organs, even beyond the stage of seedlings. This hypothesis may explain why primary leaves express a strong indirect defense by the release of herbivore induced VOCs"
Keywords:		Animals Coleoptera/*physiology Cyanides/chemistry Electron Transport/physiology Feeding Behavior/*physiology Larva/physiology Phaseolus/*chemistry Plant Leaves/*chemistry Plant Proteins/analysis;
Notes:		"MedlineBallhorn, Daniel J Schiwy, Susann Jensen, Manfred Heil, Martin eng Research Support, Non-U.S. Gov't 2008/09/02 J Chem Ecol. 2008 Oct; 34(10):1298-301. doi: 10.1007/s10886-008-9540-1. Epub 2008 Aug 30"