Focus on Standards & Assessment
Materials Needed, Preparation & Planning, Management Strategies
Intro
Activity
Why Study Predator - Prey interactions?
Activity
1
Observation
of a predator-prey interaction
Activity
2
What
makes a predator successful?
Research
Project
Designing a predator - prey experiment
Optional
Activity
Biological
Control vs. Pesticides
Case
Study
Rabbits
in Australia
Overview
& Lesson Sequence
Courses
biology, agriculture
Grades
9-10
Topics
predator-prey relationships and biological control
Organisms
aphids and host plants (pea aphids and pea plants), green lacewing larvae,
ladybird beetle adults and larvae, big-eyed bugs (optional), and preying
mantids (optional)
Time
Required
Approximately three weeks not including time needed for plant propagation
and hatching mantid egg cases An additional two weeks for the Optional
Activity -- Biological Control versus Pesticides
In the Great Gravidity lesson, we looked at how resource availability affects the birth and death rates of a population. In this lesson we will expand our perspectives on population regulation to include interactions between species and between predators and their prey. While predator-prey relationships are interesting studies in themselves, this lesson approaches the topic from the perspective of predators as a form of biological control of insect pests. Biological control utilizes natural enemies to control pest populations and results in less harm to plants, people and the environment. We’ll use biological control of aphids as our model. Other examples of biological control are explored in the optional case study.
This lesson facilitates student use of scientific inquiry and increases knowledge and understanding of biological control and predator-prey relationships in populations and ecological systems. Through activities, a research project and a real-life case study, students explore predators, prey and their relationships including using predators as a form of biological control. This lesson’s long-term research project and associated activities mirror real-world scientific research in that students will be collaboratively setting up an experiment, collecting, organizing and interpreting data, then presenting their results. There are ample opportunities for students to ask their own questions, develop hypotheses and design experiments.
Lesson
Sequence
This lesson begins with three introductory activities that set up the
research project. Each activity can be extensive or take only a
couple of class periods depending on student questions. Activity 3 is
optional and Activity 4 brings the concepts together in a case study.
If Activity 3 is not done, some of the concepts in Activity 4 may be new
to the students.
Introduction: The introductory activity provides an opportunity to assess students’ understandings and misconceptions about predator-prey interactions. A list of student questions can be initiated and added to as the lesson progresses. The questions can be pursued as individual student research projects and/or be addressed at the end of the lesson to assess what students have learned.
"Observing predators and their prey" piques student interest with observation of encounters between live predacious insects and prey insects. Students are introduced to some of the laboratory techniques that may be used in the Research Project and Activity 3.
"What makes a predator successful?" encourages students to explore the adaptations that make a predator successful. Anatomical adaptations, especially mouthparts, of several insect predators are compared and contrasted.
Research Project--"Designing a predator-prey experiment": Based on the introductory activities, students come up with their own question and design an experiment to answer it. Depending on students’ prior knowledge of scientific investigations and/or their laboratory skills, the project may be very open-ended or there may be one or two questions they can all explore. If students are capable, the project offers an opportunity for them to engage in scientific research. Depending on their questions, students will discover interactions between predators and their prey, effects on prey populations, how many prey a predator can/does eat in a given period of time (saturation), carrying capacity of the environment (both prey and predator), predators as specialists or generalists, and competition among predators.
"Biological Control versus Pesticides" (optional): During a two-week study, students collect data that help them further explore the role of predators in the ecosystem. This activity also introduces insecticides and asks students to think about the advantages and disadvantages of using different methods of insect pest control.
"Case Study - Rabbits in Australia" encourages students to apply what they have learned in the previous activities to a historical "pest" problem. It can be extensive, involving students in role-playing, panel discussions and/or debates, or a basic activity that emphasizes some of the major concepts of biological control.
Learning
Objectives
The student will be able to:
- quantify predation success given predator and prey interactions.
- describe structural (morphological) and behavioral adaptations that have made the predators and prey successful.
- design a scientific investigation to answer their own question
- observe and make predictions about predator/prey interactions
- explain the role of predators and parasites in an ecosystem.
- describe the role of humans in altering a natural balance in an ecosystem.
Prior Knowledge Needed
- Familiarity with scientific research such as: defining a problem, selecting testing materials, differentiating between controls and variables, using observation and measuring tools, collecting and organizing data, and drawing conclusions from data
- General idea of ecosystems and populations; food webs and pyramids including roles and terminology - carnivores,herbivores,omnivores,parasites.
- Population growth and carrying capacity (see Great Gravidity).
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