Lambir Nepenthes project (proposal)

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The Effects of Morphology and Pitcher Age on Insect Yield in Nepenthes in Lambir

Fikty Aprilinayati, Shana Caro, and Serena Zhao



Nepenthes is a genus of carnivorous plants with an especially diverse representation on the island of Borneo; there are 25 species found in Sarawak. The specialized leaves of the Nepenthes form a pitcher as a mechanism for carnivory: insects are attracted to the colour and nectar produced on the lid of the pitcher and are digested in the pooled fluid inside the pitcher. Nepenthes is a subject of study that provides an insight into the uncommon phenomenon of plant carnivory. This analysis of Nepenthes carnivory explores trade-offs in costly mechanisms of varying effectiveness.


  • What are the effects of differences in relative pitcher age and differences in pitcher morphology on insect yield in Nepenthes?


Because there is a wide variation in the morphology of costly pitchers, we expect it to have a greater effect on insect yield than pitcher age. Specifically, pitchers with higher capacities and wide peristomes (rims) can be expected to have a higher yield, regardless of pitcher age. The null hypothesis is that morphology is not the most statistically significant factor. We will also examine the environmental factors that may influence pitcher morphology, such as light exposure, soil type, and soil pH.


  • We will measure peristome width relative to height of the pitchers, as well as volume.
  • To quantify the yield of each pitcher, we will remove the contents of the pitcher and measure the concentration of insect heads with the dry matter suspended in a standard amount of water. We will also count the number of large, intact insects within each pitcher.
  • To estimate pitcher age, we will count leaves (since the newest pitchers form on the newest leaves), and so we can know the order of pitcher growth. We will also categorize approximate pitcher degradation by categorizing pitchers as healthy, with holes, healthy color vs. unhealthy color, and percentage dead.
  • We will categorize light exposure as: direct sunlight, indirect sunlight, or shaded. We will categorize environment as disturbed and polluted, disturbed and unpolluted, and undisturbed.
  • We will measure soil pH with litmus paper.
  • We will categorize soil type as: sandy loam, loam, fine loam, or clay.


To support our hypothesis, pitcher morphology must be closely correlated with insect yield. We will analyze the data using the correlation test. If morphology data is closely correlated with that of the insect yield, it indicates that the yield is more dependent on morphological factors of the pitchers, over the pitcher age. If pitcher age is more closely correlated with yield, morphology will not be expected to play as large a role as hypothesized.


Clark, C. and Lee, C. (2004). Pitcher Plants of Sarawak. Natural History Publications (Borneo), Kota Kinabalu.