title: Oil adsorption ability of three-dimensional epicuticular wax coverages in plants.
abstract: Primary aerial surfaces of terrestrial plants are very often covered with three-dimensional epicuticular waxes. Such wax coverages play an important role in insect-plant interactions. Wax blooms have been experimentally shown in numerous previous studies to be impeding locomotion and reducing attachment of insects. Among the mechanisms responsible for these effects, a possible adsorption of insect adhesive fluid by highly porous wax coverage has been proposed (adsorption hypothesis). Recently, a great decrease in insect attachment force on artificial adsorbing materials was revealed in a few studies. However, adsorption ability of plant wax blooms was still not tested. Using a cryo scanning electron microscopy approach and high-speed video recordings of fluid drops behavior, followed by numerical analysis of experimental data, we show here that the three-dimensional epicuticular wax coverage in the waxy zone of Nepenthes alata pitcher adsorbs oil: we detected changes in the base, height, and volume of the oil drops. The wax layer thickness, differing in samples with untreated two-layered wax coverage and treated one-layered wax, did not significantly affect the drop behavior. These results provide strong evidence that three-dimensional plant wax coverages due to their adsorption capability are in general anti-adhesive for insects, which rely on wet adhesion.
authors.affiliation: Department of Functional Morphology and Biomechanics, Zoological Institute, Kiel University, Am Botanischen Garten 9, Kiel, 24098, Germany.
authors.forename: Elena V
authors.initials: EV
authors.lastname: Gorb
authors.affiliation: Department of Functional Morphology and Biomechanics, Zoological Institute, Kiel University, Am Botanischen Garten 9, Kiel, 24098, Germany.
authors.forename: Philipp
authors.initials: P
authors.lastname: Hofmann
authors.affiliation: Department of Functional Morphology and Biomechanics, Zoological Institute, Kiel University, Am Botanischen Garten 9, Kiel, 24098, Germany.|Department N5, Donetsk Institute for Physics and Engineering, R. Luxemburg Str. 72, Donetsk 83112, Ukraine.
authors.forename: Alexander E
authors.initials: AE
authors.lastname: Filippov
authors.affiliation: Department of Functional Morphology and Biomechanics, Zoological Institute, Kiel University, Am Botanischen Garten 9, Kiel, 24098, Germany.
authors.forename: Stanislav N
authors.initials: SN
authors.lastname: Gorb
mesh_terms: D000327:Adsorption; D000073559:Caryophyllales / Q000737:chemistry / Q000378:metabolism*; D020285:Cryoelectron Microscopy; D009821:Oils / Q000737:chemistry*; D014867:Water / Q000737:chemistry; D014885:Waxes / Q000737:chemistry*
chemical_list: D009821:Oils; D014885:Waxes; D014867:Water