1. What strategies does the species you selected use to reduce the effects of herbivores? Explain them. Does the species you selected form mutualistic or parasitic association with another species? Does your species benefit or suffer from the association?

2. Herbivores have three immediate effects on plants: (i) the loss of photosynthetic tissue; (ii) the removal of meristems; and (iii) the loss of stored nutrients (Noy Meir, 1 993). Explain how each of these can influence the growth and survival of a weed.

3. Research the relationship between a weedy plant and its biological control agents. Was the agent successful at controlling the weed? Explain why or why not.

4. Explain why the cactus moth borer follows meta-population dynamics in Australia where it was introduced to control the prickly pear cactus.

5. Explain how parasitic weeds might be controlled by the use of 'trap' crops.

6. What is the relationship between weeds and their mycorrhizal associations?

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