Foraging behavior of insect pollinators in the presence of ambush predators


Students investigate how ambush predators such as the common ambush bug (Phymata americana) or the common crab spider (Misumena vatia) influence the foraging behavior of insect pollinators on flowers. If pollinators detect ambush predators and avoid visiting a flower or inflorescence, the hosting plant may suffer decreased pollen uptake and deposition. This could result in decreased plant fitness (i.e. decreased seed production or siring success) through this indirect negative effect by ambush predators. This project involves an experimental manipulation of predator presence and subsequent pollinator observation over the course of a single or several lab periods. Students read introductory articles and take a pre-project online quiz, collect data in the field, analyze the class data, interpret literature sources and write a major report.


Ivana Stehlik1 and Christina Thomsen2

1- Department of Biological Sciences, University of Toronto at Scarborough, 1265 Military Trail, Toronto, ON, Canada, M1C 1A4; ivana.stehlik@utoronto.ca

2- Department of Biology, University of Toronto at Mississauga, 3359 Mississauga Road, Mississauga, ON, Canada, L5L 1C6; c.thomsen@utoronto.ca


3 lab hours (in addition to any travel time, if the instructor scouts for old field vegetation occupied by ambush predators).


9 - 10 hours to read two introductory articles, take a pre-project online quiz, analyze the data, collect and interpret literature sources and write a major report.


  • Online quiz as a motivation for self-directed learning and preparation
  • Class data set
  • Major report, in which students submit a formal report that includes an introduction to the research field and particular study question, the materials and methods used, the results of the statistical analyses, and a discussion about the findings, with reference to primary research articles


This field project is best conducted in meadows or old-field vegetation where ambush predators are generally abundant, and in late summer to fall when they are most active. There are many plant species suitable as arenas for observation, but good choices are generalist-pollinated species where flowers are arranged in inflorescences that can accommodate pollinators of different shapes and sizes. Queen Anneís lace (Daucus carota) or various representatives of Asteraceae (Solidago, or Euthamia) are prime examples. Because all of these plant species and genera flower in late summer to fall, they make this lab suitable for fall classes.


This field activity could be used in two ways: (1) in upper-level (specialized) ecology courses (e.g. behavioral ecology or field ecology courses) for 12-20 undergraduate students using the instructions outlined in the present document, where students cooperatively collect their data, and (2) in upper-level, two-week summer field course settings as an individual student project. In the latter, the project approach should be more inquiry-based.


Public research and undergraduate university of approximately 10,000 students.


This project would fit general ecology or upper division ecology courses at institutions of all sizes. The lab is simple in design and requires no special technical skills or tools thus could be transferred to non-majors general biology classes, but access to suitable old-field or meadow communities is key.


  • Full Article Text [doc], [pdf]

Description of other Resource Files:

  • Pre-lab quiz for formative evaluation [doc]
  • Sample student data sheet [doc]
  • Student instructions on how to write a major report [doc]
  • Scoring rubric for student reports [doc]
  • Sample student data [xls]
  • Sample data analysis [doc]


This field project was devised, formulated and optimized by CT during a summer field course in experimental ecology and evolution taught by IS at the University of Toronto, Koffler Scientific Reserve, as an independent research project. IS broadened in scope and adapted CTís protocol, and created the pre-formative quiz based on the suggested readings so that the project could be used as a whole-class exercise to create a class data set.


Ivana Stehlik and Christina Thomsen. 7 March 2011, posting date. Foraging behavior of insect pollinators in the presence of ambush predators. Teaching Issues and Experiments in Ecology, Vol. 7: Experiment #1 [online]. http://tiee.esa.org/vol/v7/experiments/stehlik_thomsen/abstract.html

A: A cryptic common crab spider (Misumena vatia) in a sit-and-wait position for insect pollinators on Queen Anneís lace (Daucus carota; picture taken by Janani Srinivasan). B: A crab spider that has captured a fly (Diptera; picture taken by Janani Srinivasan). C: Female (lighter in color and better camouflaged) and male (darker, holding on to the female) ambush bugs (Phymata americana) on goldenrod (Solidago sp.). Females are the primary hunters, while males, once paired up, often exploit females for foraging (picture taken by Christina Thomsen).

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