Patterns of nectar secretion in five Nepenthes species from Brunei Darussalam, Northwest Borneo, and implications for ant–plant relationships
ABSTRACT The distribution of nectaries and the temporal and spatial pattern of nectar secretion are compared for five Bornean lowland species of Nepenthes (N. a¬lbomarginata, N. b¬icalcarata, N. gracilis, N. mirabilis var. echinostoma, N. rafflesiana) based on results from field studies conducted in Brunei Darussalam, Northwest Borneo. Leaf development together with temporal and spatial pattern of nectar secretion is also given for cultivated Nepenthes bicalcarata, a myrmecophytic species that, in terms of nectar produc¬tion, appears to be exceptional within the genus.
The number of ants trapped in frequently visited pitchers of N. b¬icalcarata and N. mirabilis var. echinostoma was counted over a set period. The percentage of trapped individuals was remarkably small. It ranged from 0.75 to 1.59% of present ants in N. bicalcarata and from 0.34 to 0.42% in N. mirabilis.
The function of extrafloral nectaries in Nepenthes with special reference to N. bicalcarata as well as implications for ant-plant relationships are discussed.
Full-textDOI: · Available from: Marlis Merbach, Sep 26, 2015
[Show abstract] [Hide abstract]
- "Bohn and Federle, 2004; Bauer and Federle, 2009; Gaume and Di Giusto, 2009). These include the nectar glands (Merbach et al., 2001; Bauer et al., 2008), olfactory and visual cues (Moran, 1996; Moran et al., 1999, 2012; Bauer et al., 2011), the slippery peristome surfaces (Bauer et al., 2009, 2015), viscoelastic digestive fluids (Gaume and Forterre, 2007), and waxy inner surfaces (Gaume et al., 2004). "
ABSTRACT: Question: How does the pitcher plant Nepenthes hemsleyana facilitate roosting of mutualistic bats? Hypothesis: Pitchers have adaptations that match the shape and body size of small woolly bats. Organisms: The pitcher plant Nepenthes hemsleyana, its close relative N. rafflesiana, and the woolly bat Kerivoula hardwickii. Field sites: Peat swamps and heath forests in western Brunei Darussalam on the island of Borneo. Methods: We measured various morphological traits of N. hemsleyana that might facilitate bat roosting. We compared these traits with those of N. rafflesiana, which is not visited by bats. We compared the sizes and characteristics of the pitchers with the body sizes of roosting bats. Conclusions: As predicted, aerial pitchers matched the body size of bats and had lower digestive fluid levels than pitchers of a close relative. Thus, small morphological differences between closely related species have caused rapid dietary niche divergence.Evolutionary ecology research 08/2015; 16:581-591. · 0.90 Impact Factor
[Show abstract] [Hide abstract]
- "Nutrient gain in a myrmecotrophic relationship can only occur if the ants acquire nutrients from sources unavailable to the host plant itself. C. schmitzi ants have a cryptic lifestyle, and consistent with previous reports , , , we have only very rarely observed them outside N. bicalcarata (during at total of >200 hours of day and night-time observations, we saw them only twice walking on the leaves of another plant that was in direct contact with N. bicalcarata). Thus, if these ants are indeed nutritional mutualists, how can they increase the nutrient supply for N. bicalcarata? "
ABSTRACT: Many plants combat herbivore and pathogen attack indirectly by attracting predators of their herbivores. Here we describe a novel type of insect-plant interaction where a carnivorous plant uses such an indirect defence to prevent nutrient loss to kleptoparasites. The ant Camponotus schmitzi is an obligate inhabitant of the carnivorous pitcher plant Nepenthes bicalcarata in Borneo. It has recently been suggested that this ant-plant interaction is a nutritional mutualism, but the detailed mechanisms and the origin of the ant-derived nutrient supply have remained unexplained. We confirm that N. bicalcarata host plant leaves naturally have an elevated (15)N/(14)N stable isotope abundance ratio (δ(15)N) when colonised by C. schmitzi. This indicates that a higher proportion of the plants' nitrogen is insect-derived when C. schmitzi ants are present (ca. 100%, vs. 77% in uncolonised plants) and that more nitrogen is available to them. We demonstrated direct flux of nutrients from the ants to the host plant in a (15)N pulse-chase experiment. As C. schmitzi ants only feed on nectar and pitcher contents of their host, the elevated foliar δ(15)N cannot be explained by classic ant-feeding (myrmecotrophy) but must originate from a higher efficiency of the pitcher traps. We discovered that C. schmitzi ants not only increase the pitchers' capture efficiency by keeping the pitchers' trapping surfaces clean, but they also reduce nutrient loss from the pitchers by predating dipteran pitcher inhabitants (infauna). Consequently, nutrients the pitchers would have otherwise lost via emerging flies become available as ant colony waste. The plants' prey is therefore conserved by the ants. The interaction between C. schmitzi, N. bicalcarata and dipteran pitcher infauna represents a new type of mutualism where animals mitigate the damage by nutrient thieves to a plant.PLoS ONE 05/2013; 8(5):e63556. DOI:10.1371/journal.pone.0063556 · 3.23 Impact Factor
[Show abstract] [Hide abstract]
- "In fully developed, open pitchers (i.e. functional traps) the largest quantities of nectar are secreted on the peristome and under the pitcher lid . "
ABSTRACT: Carnivorous pitcher plants capture prey with modified leaves (pitchers), using diverse mechanisms such as 'insect aquaplaning' on the wet pitcher rim, slippery wax crystals on the inner pitcher wall, and viscoelastic retentive fluids. Here we describe a new trapping mechanism for Nepenthes gracilis which has evolved a unique, semi-slippery wax crystal surface on the underside of the pitcher lid and utilises the impact of rain drops to 'flick' insects into the trap. Depending on the experimental conditions (simulated 'rain', wet after 'rain', or dry), insects were captured mainly by the lid, the peristome, or the inner pitcher wall, respectively. The application of an anti-slip coating to the lower lid surface reduced prey capture in the field. Compared to sympatric N. rafflesiana, N. gracilis pitchers secreted more nectar under the lid and less on the peristome, thereby directing prey mainly towards the lid. The direct contribution to prey capture represents a novel function of the pitcher lid.PLoS ONE 06/2012; 7(6):e38951. DOI:10.1371/journal.pone.0038951 · 3.23 Impact Factor