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SUMMARY:Grasses bite back: Silica as an anti-herbivore defence - Professor
  Susan Hartley\, University of Sussex
DTSTART:20061130T160000Z
DTEND:20061130T170000Z
UID:TALK5290@talks.cam.ac.uk
CONTACT:3901
DESCRIPTION:Many plants\, particularly grasses\, contain high levels of si
 lica\, but the functional significance of this remains unclear. Although s
 ilica-containing abrasive diets are thought to have driven the co-evolutio
 n between grasses and their mammalian grazers\, the effectiveness of silic
 a as a plant defence\, particularly the mechanism by which it impacts on h
 erbivore performance\, remains largely untested. In this seminar I will sh
 ow 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 reducin
 g 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 le
 vels of silica so have reduced body mass. Furthermore\, feeding by voles a
 ctually induces high levels of silica in grasses\, far higher than those p
 roduced by artificial damage. The vole-induced increases in silica are suf
 ficient to deter further feeding\, suggesting a dynamic feedback response 
 defending grasses against future herbivore damage. I propose herbivore-ind
 uced silica defence as a mechanism by which food quality could influence t
 he reproductive performance and population growth of small mammalian herbi
 vores. \n\nhttp://www.sussex.ac.uk/biology/profile118220.html
LOCATION:Department of Plant Sciences\, Large Lecture Theatre
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