1. Biological control methods.
Aphids eat my blackcurrant bush, and I get fewer blackcurrants to eat. I could
spray the bush with a pesticide, or
buy more ladybirds to add to my garden.
I should only have to apply ladybirds once to my blackcurrant bush, whereas I might have to spray it several times with pesticides to get the same length of effect. Suggest reasons for this difference.
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DDT kills ladybirds as well as pests. Thinking about food webs, why would using DDT make you more likely to keep using DDT in the future?
6 The disease malaria kills about a million people a year. DDT has saved millions of human lives from malaria, especially in Africa, by being used to kill mosquitos. Using what you’ve learned today, write a description in your books for the public about the advantages and disadvantages of using DDT.

2. Bioaccumulation