What is biological control?

Learning Outcomes:

Students can describe what biological control is and can name a biological agent used for one of our common weeds.

Resources required:

1. Landcare Research Fact Sheets or Internet site
   
2. Weedbuster Biological Control Of Weeds Word Search
   
3. Biological control of Weeds board game

Activities:

1. Group Case Study! Choose a biological control agent used for one of our common weeds e.g. ragwort flea beetle used to help control ragwort.
   
   Research these questions and present your case study in an interesting format.
   
   1. What is the name of your biological control agent?
   2. Where does it come from?
   3. How does it work?
   4. Is your biological control agent successful in controlling your chosen weed?
   5. Are there any special safety procedures or things to consider with your agent?
   6. Draw a picture of your biological control agent.
      
2. Complete the Weedbuster Biological Control Of Weeds Word Search. Find and write the meanings to any words you are unsure of!
   
3. Play the Biological Control Of Weeds board game. What new ideas does the game contain? Find out the meaning of any new words.

Reflection:

Can you describe what biological control is?

Add any new ideas to your Pool of Knowledge.

Teachers' Notes:

Biological control

Biological control is when one living organism is used to control another. In recent years insects and fungi have been found which eat or damage particular species of plant. These insects are often bred and released to help deal with a particular weed problem.

All of our weeds are introduced plants which arrived here without the natural biological controls associated with them in their countries of origin. A good example is ragwort. The ragwort flea beetle was introduced into New Zealand a few years ago. It can only survive on ragwort. It lays its eggs at the base of the plant and these hatch into larvae. The larvae eat the roots of the plant, eventually killing it. It has been a very successful method of controlling ragwort and its population, and once introduced to an area is self sustaining. It has had obvious benefits for farmers.

Landcare Research is the organisation who research and import biological control agents. Biological control will rarely wipe out a plant but is a useful control aid. New biological control agents undergo years of trials and studies before being released. Scientists have to make sure they will not harm any other plants, carry diseases or pose any threat to the environment.

The Biological Control of Weeds board game gives an idea of the issues involved in this research.

You could bring a population of gorse spider mites into your classroom to study and rear. Landcare Research or your Regional Council Pest Plant Officer could assist you.

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