User Tools

Site Tools


Group 8

Mind the Trap: Predator-Prey relationship in carnivorous pitcher plants

Wiki site of the practical exercise of the VIII Southern-Summer School on Mathematical Biology.

Here you will find the exercise assignment and the group's products.

If you are a group member login to edit this page, create new pages from it, and upload files.


Some specialized small insects, such as Tripteroides tenax, are able to lay eggs in the fluids present in carnivorous pitcher plants (e.g. species of Nepenthes genus). In their aquatic life stages, whilst developing, these small insects use and transform the compounds in these fluids into nutrients, such as ammonium, which Nepenthes can absorb and use for growth and reproduction.

 Figure 1: The web built by //X. beaveri// on the pitcher of //Nepenthes ampullaria// Nonetheless, some predatory species may take advantage of such relationship and also lay their eggs on the insides of carnivorous pitcher plants in order to prey on another species' emerging adults. In their larval stage, for example, Xenoplatyura beaveri build small webs at the liquid surface in pitchers (see figure), snaring their hasty neighbours to later prey upon them.

Figure 1:The web built by X. beaveri on the pitcher of Nepenthes ampullaria.

The role of predatory species such as Xenoplatyura beaveri in their relation with carnivorous pitcher plants has been studied recently. After devouring their prey, these larvae's feces, which contain nutrients for the plants, fall on the pitcher an contribute to the deposit of nutrients therein.

However, the net effect of this predator-prey relationship for Nepenthes remains in discussion. If, on the one hand, the increase of nutrients deposit may allow the net effect to be classified as positive for carnivorous pitcher plants, on the other, their main contributors' population size is decreased due to predation, leading to less nutrient in their pitchers and, consequently, reduced plant reproduction on the long run.


Build a mathematical model that incorporates the dynamics of this biological system. Analyze the model and use it to formulate and answer questions you may find along the way.

Suggested Questions

  • Is the presence of predators actually beneficial to Nepenthes population? How could you access the variation in plant population growth?
  • Is it possible for an excess of predators lead both the plants and their insect inquilines to extinction?
  • Another interesting aspect of this system is that, through the construction of nets, X. beaveri may end up catching Nepenthes' prey, configuring a kleptoparasitic relationship between these species.


  1. LAM, Weng Ngai et al. Predatory dipteran larva contributes to nutrient sequestration in a carnivorous pitcher plant, 2018, Biology Letters. Full text
  2. MOGI, M.; CHAN, K. L. Predatory habits of dipteran larvae inhabiting Nepenthes pitchers, 1996, Raffles Bulletin of Zoology. Full text
2019/groups/g8/start.txt · Last modified: 2019/01/14 00:43 by poloni