Slippery or sticky? Functional diversity in the trapping strategy of Nepenthes carnivorous plants

Authors

  • Vincent Bonhomme,

    1. Université Montpellier II, CNRS, UMR AMAP: botAnique et bioinforMatique de l’Architecture des Plantes, CIRAD – TA A51/PS2 Boulevard de la Lironde, F-34398 Montpellier cedex 5, France
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  • Hervé Pelloux-Prayer,

    1. Université Montpellier II, CNRS, UMR AMAP: botAnique et bioinforMatique de l’Architecture des Plantes, CIRAD – TA A51/PS2 Boulevard de la Lironde, F-34398 Montpellier cedex 5, France
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  • Emmanuelle Jousselin,

    1. INRA, UMR CBGP, Campus International de Baillarguet, CS 30016, 34988 Montferrier-sur-Lez, France
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  • Yoël Forterre,

    1. CNRS, Université de Provence IUSTI, Technopole Château-Gombert, 13000 Marseille, France
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  • Jean-Jacques Labat,

    1. Pépinière Nature et Paysages et Jardin Botanique de Plantes Carnivores, Peyrusse-Massas, France
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  • Laurence Gaume

    1. Université Montpellier II, CNRS, UMR AMAP: botAnique et bioinforMatique de l’Architecture des Plantes, CIRAD – TA A51/PS2 Boulevard de la Lironde, F-34398 Montpellier cedex 5, France
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Author for correspondence:
Vincent Bonhomme
Tel: +33 (0)4 67 61 7166
Email: vincent.bonhomme@cirad.fr

Summary

  • The pitcher-shaped leaves of Nepenthes carnivorous plants have been considered as pitfall traps that essentially rely on slippery surfaces to capture insects. But a recent study of Nepenthes rafflesiana has shown that the viscoelasticity of the digestive fluid inside the pitchers plays a key role.
  • Here, we investigated whether Nepenthes species exhibit diverse trapping strategies. We measured the amount of slippery wax on the pitcher walls of 23 taxa and the viscoelasticity of their digestive liquid and compared their retention efficiency on ants and flies.
  • The amount of wax was shown to vary greatly between species. Most mountain species exhibited viscoelastic digestive fluids while water-like fluids were predominant in lowland species. Both characteristics contributed to insect trapping but wax was more efficient at trapping ants while viscoelasticity was key in trapping insects and was even more efficient than wax on flies. Trap waxiness and fluid viscoelasticity were inversely related, suggesting the possibility of an investment trade-off for the plants.
  • Therefore Nepenthes pitcher plants do not solely employ slippery devices to trap insects but often employ a viscoelastic strategy. The entomofauna specific to the plant’s habitat may exert selective pressures, favouring one trapping strategy at the expense of the other.

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