Contrasting impacts of herbivore induction and elevated atmospheric CO2 on silicon defences and consequences for subsequent herbivores

Fikadu N. Biru*, Christopher I. Cazzonelli, Rivka Elbaum, Scott N. Johnson

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


Plants are often sequentially attacked by multiple herbivores; feeding by one herbivore can alter host plant quality that affects the performance of subsequent herbivores. Previous studies suggest that silicon (Si) is a highly inducible defence in grasses (Poaceae) following herbivory, so could mediate such temporally separated insect herbivore interactions. Elevated atmospheric CO2 concentrations (eCO2), in contrast, often reduce Si accumulation, which potentially weakens this interaction. We examined the effects of prior feeding by Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) on the performance of crickets, Acheta domesticus (L.) (Orthoptera: Gryllidae), subsequently feeding on the same plant. We used Brachypodium distachyon (L.) P. Beauv. grass supplemented or non-supplemented with Si and grown in the glasshouse maintained at ambient (aCO2) or eCO2 concentrations. As hypothesized, prior feeding by caterpillars induced Si accumulation. Despite eCO2 reducing Si accumulation, initial herbivore induction of Si negated the effects of eCO2. Both, previous caterpillar herbivory and Si supplementation reduced cricket performance. Si induction by successive herbivory was additive. Plant biomass was similar in plants attacked by caterpillars alone or both herbivores, suggesting that initial Si induction by caterpillars deterred feeding by crickets. Our results demonstrate that Si induction by one herbivore negatively impacts successive herbivores, as has been demonstrated for secondary metabolite-mediated interactions. Uniquely, however, Si induction is an irreversible defence and potentially a stronger, or perhaps longer-lasting mediator of such herbivore interactions in some plant taxa.

Original languageAmerican English
Pages (from-to)681-688
Number of pages8
JournalEntomologia Experimentalis et Applicata
Issue number8
StatePublished - Aug 2022

Bibliographical note

Publisher Copyright:
© 2022 The Netherlands Entomological Society.


  • Acheta domesticus
  • Brachypodium distachyon
  • Gryllidae
  • Helicoverpa armigera
  • Lepidoptera
  • Noctuidae
  • Orthoptera
  • Poaceae
  • carbon dioxide
  • caterpillars
  • crickets
  • induced plant defence
  • silicon


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