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What are pesticides?
Chemicals which kill insects
What are the advantages of pesticides?
- Can potentially kill all pests on a crop
- Starts working immediately
What are the disadvantages of pesticides?
- Leaves residue on crops which can be poisonous to humans
- Will kill all insect species including helpful ones that eat other insects or pollinators, this also reduces food supplies for consumers such as birds
- Insects can evolve resistance to the pesticide
- Vary in how long they take to be broken down by bacterial enzymes and biodegrade
How could the use of a pesticide lead to bioaccumulation?
- If used in low concentrations some pests are not killed but contain low concentrations of the chemical
- Predators such as birds eat many of these insects and the pesticide accumulates in their fat stores
- Large predators eat many of the birds and levels of the pesticide in fat stores becomes fatally high
What is a biological control?
The introduction of a natural predator or parasite of the insect pest that will kill it
What are the advantages of biological control?
- It is specific to the pest species
- Cheaper as it only needs to be applied once and it can then reproduce rather than regular applications of chemicals
- Reduces the use of insecticides so pests are less likely to develop resistance
- No toxic residue left on plants
What are the disadvantages of biological controls?
- Takes time for the biological control organisms to reach numbers that reduce pest numbers
- Pest numbers will never reach 0 due to predator-prey relationships
- Control organism may become a pest due to the absence of a natural predator (cane toad)
What does integrated pest management combine?
- Chemical pesticides (starts work immediately whilst control organisms are reproducing)
- Biological control
- Selecting crops for pest resistance
- Providing habitats for natural predators (hedgerows)
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