5.4 - Pesticides and Biological Control

- Large fields of crops all at the same time - Monoculture 
- Monoculture - very susceptible to pests - they use the crop as a food source - this reduces the productivity of farming (food and financially)


1. Pesticides - chemicals - designed to kill the pest 


Advantages: 
- Chemicals - easy to obtain  
- Easy to apply - spray 
- Very effective 


Disadvantages: 
- Toxic - may kill other plants and animals other then the pests and may be harmful to humans 
- Bio accumulation - pesticide builds up through the food chain causing problems for higher trophic levels (DDT) 
- Mutation in the pest leads to resistance - pesticide must then be applied at higher concentrations which then make it more toxic





2. Biological Control 
Example in Australia 

Advantages: 
- No toxic chemicals involved 
- Less impact on man/wildlife 


Disadvantages: 
- Not 100% effective 
- Difficult to control - always a danger that the introduced species will find an alternative prey. e.g. Cane toad (australia) 
-  Difficult to match a predator to the prey. May not be able to find an animal that can remove the pest