Card Set Information
Biology Productivity camturnbull
AQA BIOL4 Productivity
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)
Selecting crops for pest resistance
Providing habitats for natural predators (hedgerows)