Can flower types be predictors of insect pollinators?
Fast fact: Even though insects make up more than 70% of Australia's biodiversity, plant scientists are concerned about our role in weakening the plant/pollinator relationship. Of the 220,000 species of insects in Australia, 35% remain undocumented, compared to 5% of vertebrate species.
|Bees||Flower types: tubular||Flies||Pollen|
|Beetles||Flower types: brush||Insects||Pollinator|
|Butterflies||Flower types: open||Nectar||Species|
Pose the focus question
Before you get to the focus question, ask your students some pre-assessment questions.
- Why do flowers need a pollinator?
- What types of pollinators are there?
- What types of flower shapes are there?
- How would you describe the NSW flower emblem (Waratah)?
- Why does an insect visit flowers?
- What attracts insects to flowers?
Dicuss the focus question: Can flower types be predictors of insect pollinators? List all answers, questions and concepts as they arise. Demonstrate plant insect interrelation with Plant life cycle and processes diagram. Discuss where bees, butterflies, beetles and other insects, including ants, fit in this cycle.
If your students get stuck, read through What is pollination as a class.
Using a digi-cam/microscope or magnifying glasses, look at butterflies, bees, wasps, flies, beetles that have been temporarily refrigerated. Focus on mouth parts that will suck up the food for the insect. Compare and contrast mouth parts. Draw the mouth parts, or use digi-cams to view on computers.
Move out to the school grounds or gardens to observe flower types. Use the Plants and insects in our garden matrix. Choose three contrasting flower types to dissect under a magnifying glass or digi-cam.
Hypothesise about the attractants and devise an experiment to test the hypothesis e.g Are colours an attractant? Experiment with different coloured pan traps (see Invertebrate Collection Manual) Revisit the garden with the Pollinator preference key. Create a profile of the insect life in the garden.
- Search for and watch videos on hand pollination techniques.
- Create a craft flower and pipe cleaner insect with our How to make a bee pollinator activity sheet.
- Create an experiment that tests the role of flower shape in attracting native versus feral bees in attracting (see P2P presentation).
As a class, discuss whether the school garden is a rich source of insect pollinators and visitors. Which plants would be bee attractors? Which would be butterfly attractors? Can you see evidence of the insects visit? What are those clues?
Choose a mature tree (e.g Acacia, Leptospermum) and observe the insects on it by leaf beating technique. Discuss the role of the insects collected: pollinators, predators or dispersers?
- 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.
- Plants attract pollinators in various ways, by offering pollen or nectar meals and by guiding them to the flower using scent and visual cues. This has resulted in strong relationships between plants and the animals that pollinate them. Long- tongued bees and butterflies, and the tubular plants they pollinate are examples of such adaptation.
- However pollination can be the result of a visit from any insect who has visited a flower for a variety of purposes. Insects do visit plants and their flowers for a variety of reasons, apart from the sweet reward of nectar and the nutritious benefits of pollen. Flowers can also provide food, shelter, brooding places, pollen feeding and collection, resin and oils for nest building.