Pesticides And Biological Control

Question 1

What do pesticides disturb/affect? Why?

Answer 1

The food chain

Sprayed into creatures that destroy crops (pests) - but also kills organisms (bees and ladybirds)

Leads to animals in food chain being affected

Question 2

What is a danger of pesticides?

Answer 2

Killing animals further up in the food chain (not only bees and ladybirds)

Question 3

How were otters nearly extinct in southern England ? By which pesticides?

Answer 3

Pesticides called DDT

1. Pesticide seeps in river (like fertilisers - eutrophication)
2. Pesticides mix with water and small plants take in water with pesticide in
3. Little animals eat plants
4. Small fishes eat little animals
5. Eels eat small fishes
6. Otters eat eels with pesticide in

Question 4

What is biological control?

Answer 4

Using living organisms instead of pesticide (chemicals) to control pests

Question 5

What can be used for biological control?

Answer 5

Predators, parasites or disease to kill pests

Question 6

Give me examples used for biological control?

Answer 6

Ladybirds-
Eat aphids (pests), farmers release ladybirds in field and gardens to keep number of aphids down

Wasp and flies-
Produce larvae that developed on a host insect (the unwanted organism) to kill them.

Myxomatosis-
Kills rabbits when population grew out of control and ruined crops (in Australia)

Question 7

What are the advantages of biological control?

Answer 7

No chemical being used -
Less pollution
Less disruption of food chain
Less risk of people eating chemicals

No repeating of treatment -
Unlike pesticides that needs to be sprayed daily

Question 8

What are the disadvantages of biological control?

Answer 8

Predators might not even eat the pests

Predators could eat useful species

Predator population can increase and get out of control

Predator will not stay in the area it is needed in