Skip to main content

Trade-Offs between Silicon and Phenolic Defenses may Explain Enhanced Performance of Root Herbivores on Phenolic-Rich Plants


Phenolic compounds play a role in plant defense against herbivores. For some herbivorous insects, particularly root herbivores, host plants with high phenolic concentrations promote insect performance and tissue consumption. This positive relationship between some insects and phenolics, however, could reflect a negative correlation with other plant defenses acting against insects. Silicon is an important element for plant growth and defense, particularly in grasses, as many grass species take up large amounts of silicon. Negative impact of a high silicon diet on insect herbivore performance has been reported aboveground, but is unreported for belowground herbivores. It has been hypothesized that some silicon accumulating plants exhibit a trade-off between carbon-based defense compounds, such as phenolics, and silicon-based defenses. Here, we investigated the impact of silicon concentrations and total phenolic concentrations in sugarcane roots on the performance of the root-feeding greyback canegrub (Dermolepida albohirtum). Canegrub performance was positively correlated with root phenolics, but negatively correlated with root silicon. We found a negative relationship in the roots between total phenolics and silicon concentrations. This suggests the positive impact of phenolic compounds on some insects may be the effect of lower concentrations of silicon compounds in plant tissue. This is the first demonstration of plant silicon negatively affecting a belowground herbivore.

This is a preview of subscription content, access via your institution.

Fig. 1


  • Allsopp PG (2010) Integrated management of sugarcane whitegrubs in Australia: an evolving success. Annu Rev Entomol 55:329–349

    CAS  Article  PubMed  Google Scholar 

  • Barton CVM, Ellsworth DS, Medlyn BE, Duursma RA, Tissue DT, Adams MA, Eamus D, Conroy JP, McMurtrie RE, Parsby J, Linder S (2010) Whole-tree chambers for elevated atmospheric CO2 experimentation and tree scale flux measurements in South-Eastern Australia: the Hawkesbury Forest experiment. Agric For Meteorol 150:941–951

    Article  Google Scholar 

  • Cooke J, Leishman MR (2011) Is plant ecology more siliceous than we realise? Trends Plant Sci 16:61–68.

  • Cooke J, Leishman MR (2012) Tradeoffs between foliar silicon and carbon-based defences: evidence from vegetation communities of contrasting soil types. Oikos 121:2052–2060

    Article  Google Scholar 

  • Johnson SN, Nielsen UN (2012) Foraging in the dark – chemically mediated host plant location by belowground insect herbivores. J Chem Ecol 38:604–614

    CAS  Article  PubMed  Google Scholar 

  • Massey FP, Hartley SE (2009) Physical defences wear you down: progressive and irreversible impacts of silica on insect herbivores. J Anim Ecol 78:281–291

    Article  PubMed  Google Scholar 

  • Massey FP, Ennos AR, Hartley SE (2007) Herbivore specific induction of silica-based plant defences. Oecologia 152:677–683

    Article  PubMed  Google Scholar 

  • Mithöfer A, Boland W (2012) Plant defense against herbivores: chemical aspects. Annu Rev Plant Biol 63:431–450

    Article  PubMed  Google Scholar 

  • Oksanen J, Blanchet FG, Kindt R, Legendre P, Minchin PR, O'Hara RB, Simpson GL, Solymos P, Stevens MHH, Wagner H (2015) vegan: Community Ecology Package. URL:

    Google Scholar 

  • Reidinger S, Ramsey MH, Hartley SE (2012) Rapid and accurate analyses of silicon and phosphorus in plants using a portable X-ray fluorescence spectrometer. New Phytol 195:699–706

    CAS  Article  PubMed  Google Scholar 

  • Salminen J-P, Karonen M (2011) Chemical ecology of tannins and other phenolics: We need a change in approach. Funct Ecol 25:325–338

    Article  Google Scholar 

  • Schaller J, Brackhage C, Dudel EG (2012) Silicon availability changes structural carbon ratio and phenol content of grasses. Environ Exp Bot 77:283–287

    CAS  Article  Google Scholar 

  • Wieczorek M, Zub K, Szafrańska PA, Książek A, Konarzewski M (2015) Plant–herbivore interactions: silicon concentration in tussock sedges and population dynamics of root voles. Funct Ecol 29:187–194

    Article  Google Scholar 

Download references


We thank the teams at Sugar Research Australia and the Hawkesbury Institute for the Environment for their support throughout this project, particularly Andrew Gherlenda, Allen Eaton, and Lisa Derby for their help and advice. Funding was provided by Sugar Research Australia (project no.2014/104) and the Hawkesbury Institute for the Environment, Western Sydney University.

Author information

Authors and Affiliations


Corresponding author

Correspondence to Adam Frew.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Frew, A., Powell, J.R., Sallam, N. et al. Trade-Offs between Silicon and Phenolic Defenses may Explain Enhanced Performance of Root Herbivores on Phenolic-Rich Plants. J Chem Ecol 42, 768–771 (2016).

Download citation

  • Received:

  • Revised:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI:


  • Carbon
  • Insect herbivory
  • Phenolics
  • Silicon
  • Sugarcane
  • Trade-off