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.
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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 01/2013; 8(5):e63556. · 3.53 Impact Factor
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ABSTRACT: Using a cryo-scanning electron microscope, we studied microstructure of the slippery zone in nine Nepenthes taxa. For N. fusca, N. macrophylla, N. mirabilis, N. ventricosa, N. dicksoniana, and N. veitchii, it was examined here for the first time. Three types of the slippery zone were distinguished among the studied taxa: (1) with well-developed crystalline wax coverage, (2) with greatly reduced wax coverage, and (3) without wax crystals. These data were combined with morphometrical measurements of the two pitcher zones primarily relevant to prey catching and retaining: the slippery zone and the peristome. In species with fully developed wax coverage, the slippery zone was longer and the peristome was narrower compared to those with reduced or lacking crystalline wax. We found statistically significant negative correlation between the relative length of the slippery zone and the relative width of the peristome. Based on the analysis of the relationship between the microstructure of the slippery zone and pitcher macromorphology, two main types of pitchers in Nepenthes are proposed: (a) traps based predominantly on the waxy slippery zone and (b) peristome-based traps.Arthropod-Plant Interactions 6(1). · 1.18 Impact Factor
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ABSTRACT: Here we report a complex food web and special fluid properties in pitchers of Nepenthes mirabilis in Zhuhai, Guangdong Province, China. It attracts ants and flying insects with floral and exrafloral nectaries, color of pitcher and flower, and possibly flower odor. Its slippery rim and collar trap preys, but some wasps can hold legs on the outside of the rim. Its preys include arthropods in four classes (with nine orders in insect class), plus very few snails and lizards. Fresh fluid sinks, kills, and digests preys (including lizards) quickly, but allows flogs to live in; while old fluid allows mosquitoes to hatch in it. Fluid reaches its maximum amount at pitcher opening. Then, the pH decreases gradually from 6 to 1.9, as the color changes slowly from colorless to yellow, and finally both pH and color reverse as pitchers dying. Proteinase nepenthesins could be resulted in these special conditions through long evolutionary adaptation.Acta botanica Gallica: bulletin de la Société botanique de France 06/2005; 152(2). · 0.24 Impact Factor