Beetles were probably the world’s first animal pollinators; they pollinated cycads long before flowering plants came on to the scene. What insects are in your garden and why are they there?
What insects are visiting our garden and why?
Pose focus question. List all answers and questions as they arise.
Engage students’ interest in the mutualism of plants and insects by viewing episode 4 of “Life in the Undergrowth” or show P2P presentation (see support materials). Create a concept map around plants and insects. (see support materials C: Plant Life Cycle and Processes)
Explore the playground/garden to address the focus question, or another hypothesis which the class has agreed on (see support materials F). See support materials for suggestions for structuring field observations (E), and use the Pollinator Preference Key (J) and Flowers and Insects Observation Matrix (I). Using a camera or sketches to record which insects are visiting which flowers, and which flower types there are – include colour scent, shape, include weather data, and time. Or collect invertebrates with nets or by leaf beating or similar techniques outlined in the Invertebrate Collection Manual to examine them closely and identify them (see the Bugwise Quick Invertebrate Guide).
Explain basic flower anatomy (see support materials A) using specimens of sunflowers, melon flower, lily, bottlebrush. Discuss flower shapes and classify–tubular, other (brush, open) (see support materials K)
Elaborate on field observations. What are the cues that flowers exhibit to attract insect pollinators? What other evidence of insect visits are there? (herbivory, eggs, larvae)
Evaluate the role of flower cues by creating flowers (from craft equipment) which would entice specialist insect pollinators. Display the flowers and hypothesise about the pollinators adaptations. Discuss the diversity of garden flowers and the consequences for invertebrate diversity. Use the calendar of flowering native plants and insect activity to assist in identifying common plants. (see support materials K)
- Life in the Undergrowth, episode 4 [DVD]
- General flower anatomy diagram (A)
- Pollinator Preference Key (J)
- Flowers and Insects Observation Matrix (I)
- Plant Life Cycle and Processes (C)
- Butterfly net
- Magnifying glass
- Flower and Insect Calendar (K)
- Invertebrate Collection Manual
- Quick Invertebrate Guide
- P2P presentation (M)
- Over millions of years flowers have evolved a remarkable range of strategies to guarantee that male pollen is transferred to female parts of the flower. Insects — especially bees and wasps, butterflies, moths, beetles and flies are the predominant animal pollinators.
- They have physical characteristics that make them extremely efficient in locating flowers and transferring pollen from one flower to another.
- The typical flower contains the necessary parts for enticing pollinators and producing seeds. The centre of a flower usually contains the female, pollen-receiving pistil or carpel. The stigma at its tip is often sticky designed to trap pollen. At the base of the pistil, the generally hidden ovary protects ovules (eggs), which become seeds when fertilized. The male parts, or stamens, typically surround the pistil. They may be quite long, to maximize exposure to wind and pollinators; hidden inside the flowers, to force pollinators to touch the stigmas on their way in or out; or able to lengthen and shorten over time, as needed.
- The stamen is made up of the filament that supports the anther which produces and releases huge quantities of pollen.
- The pollen descends down the style of the sigma and fertilizes an ovule, leading to seed production. Once fertilized, the ovary wall takes in moisture and swells, becoming the fruit, which surrounds and protects the developing seeds.