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Slippery surfaces and sticky fluids of carnivorous pitcher plants: biomechanics and ecology

Supervisors: Dr Walter Federle [co-supervisor Professor Ian Wilson]

Project summary:

Nepenthes pitcher plants possess leaves modified into slippery pitfall traps. Insect visitors loose grip on the microstructured, superhydrophilic peristome surface and fall into the pitcher fluid, which can immobilize insects via its polysaccharide-based viscoelastic properties1,2. How do microtopography and wettability of the peristome influence its capture efficiency? How do Nepenthes fluids vary in stickiness and composition, and how does this affect plants and associated arthropods? How do rheological properties vary over time and how can plants cope with fluid dilution by rain? How have trapping mechanisms evolved in the genus Nepenthes? How do specialized arthropods escape the plant’s trapping mechanisms?

Insect-plant interactions play an essential role for most ecosystems, but the detailed mechanisms underlying these relationships remain poorly characterized. Carnivorous plants have developed complex structural and functional modifications of plant organs to trap arthropods and extract nutrients, and some insects in turn have developed striking counter-adaptations to overcome the plants’ traps. The aim of this project is to clarify the function and evolutionary development of slippery superhydrophilic capture surfaces and specialized polysaccharide-based trapping fluids in Nepenthes pitcher plants, and to study mechanisms of insect counter-adaptations. The mechanisms evolved in these natural insect-traps may inspire novel synthetic surfaces and materials, as well as new methods for insect pest control.

What the student will be doing:

Laboratory and field work in SE Asia (mainly Brunei) will be conducted on selected Nepenthes species. The student will 1) characterize the wetting properties of natural Nepenthes surfaces, replicas and synthetic model surfaces 2) quantify insect attachment forces and climbing performance on natural and model substrates under wet and dry conditions, 3) characterize polysaccharide concentration, ion concentration and pH in the field and laboratory, 4) quantify the fluid’s rheology (shear-thinning properties and extensional viscosity) using portable set-ups in the field3, 5) quantify the fluid’s efficiency of capturing insects, 6) study the effects of temperature, humidity and dilution by rain on fluid properties and function, as well as temporal patterns of fluid/polysaccharide secretion, 7) analyze interspecific variation of fluid, peristome and pitcher properties in the context of available phylogenetic information, and 8) explore adaptations of selected specialist insects to avoid trapping or to move within the plant’s trapping fluids.


Bohn, H. F. & Federle, W. 2004. Insect aquaplaning: Nepenthes pitcher plants capture prey with the peristome, a fully wettable water-lubricated anisotropic surface. PNAS, vol. 101, pp. 14138-14143, DOI: 10.1073/pnas.0405885101
Gaume, L. & Forterre, Y. 2007. A viscoelastic deadly fluid in carnivorous pitcher plants. PLoS ONE, vol. 2, e1185, DOI: 10.1371/journal.pone.0001185
Collett, C., Ardron, A., Bauer, U., Chapman, G., Chaudan, E., Hallmark, B., Pratt, L., Torres-Perez, M. & Wilson, D. 2015. A portable extensional rheometer for measuring the viscoelasticity of pitcher plant and other sticky liquids in the field. Plant Methods, vol. 11, 16, DOI: 10.1186/s13007-015-0059-5