Fig 3 -

Leaf anatomy and histochemistry of orchid species used in the experiments: A1. Parenchyma cells on adaxial side of leaf of C. triplicata. A2. Parenchyma cells on abaxial side of leaf of C. triplicata. A3. Parenchyma cell surface on adaxial side of leaf of C. triplicata. A4. Trichomes on abaxial side of leaf of C. triplicata. A5. Section through epidermal surface on adaxial side of leaf of C. triplicata. A6. Section through epidermal surface on abaxial side of leaf of C. triplicata. B1. Ornamentation of adaxial side of leaf of D. pallidiflavens. B2. Ornamentation of abaxial side of leaf of D. pallidiflavens. B3. Parenchymal cell surface on adaxial side of leaf of D. pallidiflavens. B4. Trichome on abaxial side of leaf of D. pallidiflavens. B5. Section through epidermal surface on adaxial side of leaf of D. pallidiflavens. B6. Trichome basal cell on abaxial side of leaf of D. pallidiflavens. C1. Surface of parenchymal cells on adaxial side of leaf of T. ferox. C2. Surface of parenchymal cells on abaxial side of leaf of T. ferox. C3. Paired trichomes on leaf of T. ferox. C4. Paired trichomes on leaf of T. ferox. C5. Section through epidermal surface on adaxial side of leaf of T. ferox. C6. Section through epidermal surface on abaxial side of leaf of T. ferox. 7–10: Histochemistry of parenchymal cells of the epidermis of leaves of C. triplicata (A), D. pallidiflavens (B), T. ferox (C). A-C7. Black arrows indicate trichomes. Staining with Etzold (lignin), A-C8. Staining with TBO (proteins), A-C9. Staining with PAS (polysaccharides), A-C10. Staining with van Kossa (calcium).</p

Fig 4 -

Relationship between A body mass (g) and footpad area (mm2) of S. octona and P. isabella. B body mass (g) and lateral side area (mm2) of S. octona and P. Isabella.</p

Schematic illustration of the centrifuge method used for measuring surface attachment forces of two different species of herbivorous snails.

The snail was placed on a freshly cut piece of orchid leaf that was clipped to an acrylic strip on a horizontally rotating platform, which was accelerated until the snail became detached. A high-speed video camera recorded the run from above and was used to determine the maximum force of detachment. D, distance from the camera to the center of the rotating platform; r, radius of platform.</p

Linear mixed model fit by REML.

Protective structures in the epidermis are essential for land plants to defend themselves against herbivores. In this study, we investigated the effect of different types of trichomes of three orchids, Calanthe triplicata, Dendrochilum pallidiflavens and Trichotosia ferox, on attachment of herbivorous land snails, using histochemistry and centrifuge experiments. Size, ornamentation and histochemistry of epicuticular trichomes on the orchid leaves were assessed with light microscopy, scanning electron microscopy and transmission electron microscopy. Total forces needed to detach two differently shaped snail species, Subulina octona and Pleurodonte isabella, were measured using a turntable equipped with a synchronized strobe. Snails were placed in two positions, either perpendicular or parallel to the main veins on the orchid leaves, both on the adaxial (= upper) or abaxial (= lower) side. The results obtained provided three new insights. First, a perpendicular or parallel position of the snails to the main veins did not significantly affect the attachment performance of either species tested. Secondly, snails detached significantly easier on leaf sides covered with a high density of lignin filled epicuticular trichomes. Thirdly, the removal of glandular trichomes did not affect the attachment forces; however, the absence of lignified trichomes increased the attachment of the snails. Our study highlights the importance of studying micro-ornamentation in combination with performance for obtaining a better understanding of the defense mechanisms employed by different species of orchids to deter herbivorous snails.</div

Safety factor of <i>Subulina octona</i> snails on trimmed orchid leaf surfaces.

Safety factor of Subulina octona snails on trimmed orchid leaf surfaces.</p

Analysis of deviance table (Type III Wald F tests with Kenward-Roger df) with mean.

Analysis of deviance table (Type III Wald F tests with Kenward-Roger df) with mean.</p

Different views of shells and live snails of the two species used in this study, <i>Pleurodonte isabella</i> (A-D) and <i>Subulina octona</i> (E-H) to illustrate the species differences in size and shape.

A, E, apical view of shells; B, F, apertural view of shells; C, G, extended (crawling) snails in lateral view; D, H, snail soles (crawling surface) attached to glass plate. Scale bar = 10 mm. Photographs by AJdW.</p

Overview of different characteristics and epicuticular properties of three species of orchids investigated in this study.

The ranges in T. ferox represent the ab/adaxial side and the ab/adaxial side respectively.</p

Mean detachment RCF and force for each combination of factors.

Mean detachment RCF and force for each combination of factors.</p

Details of herbivorous snails and orchids that were found together, both in cultivation and in the field in Indonesia.

Details of herbivorous snails and orchids that were found together, both in cultivation and in the field in Indonesia.</p