University of Cambridge > Talks.cam > Plant Sciences Departmental Seminars > Grasses bite back: Silica as an anti-herbivore defence

Grasses bite back: Silica as an anti-herbivore defence

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Many plants, particularly grasses, contain high levels of silica, but the functional significance of this remains unclear. Although silica-containing abrasive diets are thought to have driven the co-evolution between grasses and their mammalian grazers, the effectiveness of silica as a plant defence, particularly the mechanism by which it impacts on herbivore performance, remains largely untested. In this seminar I will show that increasing the levels of silica in a range of grasses does lead to them becoming more abrasive, and that this deters feeding by a range of herbivores, including voles. I will also report the first evidence that elevated levels of silica reduce the growth rates of herbivores by reducing the digestibility of grass leaves. The underlying mechanism for this is that female voles feeding on grasses containing silica fail to extract as much nitrogen from their food as voles feeding on grasses with very low levels of silica so have reduced body mass. Furthermore, feeding by voles actually induces high levels of silica in grasses, far higher than those produced by artificial damage. The vole-induced increases in silica are sufficient to deter further feeding, suggesting a dynamic feedback response defending grasses against future herbivore damage. I propose herbivore-induced silica defence as a mechanism by which food quality could influence the reproductive performance and population growth of small mammalian herbivores.

http://www.sussex.ac.uk/biology/profile118220.html

This talk is part of the Plant Sciences Departmental Seminars series.

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