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  • Publication
    Métadonnées seulement
    Herbivore-induced plant volatiles mediate host selection by a root herbivore
    (2012)
    Robert, Christelle Aurélie Maud
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    Duployer, M.
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    Doyen, G. R.
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    In response to herbivore attack, plants mobilize chemical defenses and release distinct bouquets of volatiles. Aboveground herbivores are known to use changes in leaf volatile patterns to make foraging decisions, but it remains unclear whether belowground herbivores also use volatiles to select suitable host plants. We therefore investigated how above- and belowground infestation affects the performance of the root feeder Diabrotica virgifera virgifera, and whether the larvae of this specialized beetle are able to use volatile cues to assess from a distance whether a potential host plant is already under herbivore attack. Diabrotica virgifera larvae showed stronger growth on roots previously attacked by conspecific larvae, but performed more poorly on roots of plants whose leaves had been attacked by larvae of the moth Spodoptera littoralis. Fittingly, D similar to virgifera larvae were attracted to plants that were infested with conspecifics, whereas they avoided plants that were attacked by S similar to littoralis. We identified (E)-beta-caryophyllene, which is induced by D similar to virgifera, and ethylene, which is suppressed by S similar to littoralis, as two signals used by D similar to virgifera larvae to locate plants that are most suitable for their development. Our study demonstrates that soil-dwelling insects can use herbivore-induced changes in root volatile emissions to identify suitable host plants.
  • Publication
    Métadonnées seulement
    A specialist root herbivore exploits defensive metabolites to locate nutritious tissues
    (2012)
    Robert, Christelle Aurélie Maud
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    Marti, Guillaume
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    Doyen, G. R.
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    Gaillard, Mickaël David Philippe
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    Köllner, Tobias G.
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    Giron, David
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    Body, Mélanie
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    Babst, Benjamin A.
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    Ferrieri, Richard A.
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    The most valuable organs of plants are often particularly rich in essential elements, but also very well defended. This creates a dilemma for herbivores that need to maximise energy intake while minimising intoxication. We investigated how the specialist root herbivore Diabrotica virgifera solves this conundrum when feeding on wild and cultivated maize plants. We found that crown roots of maize seedlings were vital for plant development and, in accordance, were rich in nutritious primary metabolites and contained higher amounts of the insecticidal 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one (DIMBOA) and the phenolic compound chlorogenic acid. The generalist herbivores Diabrotica balteata and Spodoptera littoralis were deterred from feeding on crown roots, whereas the specialist D. virgifera preferred and grew best on these tissues. Using a 1,4-benzoxazin-3-one-deficient maize mutant, we found that D. virgifera is resistant to DIMBOA and other 1,4-benzoxazin-3-ones and that it even hijacks these compounds to optimally forage for nutritious roots.