5.4b - Biological control

5.4 understand the reasons for pest control and the advantages and disadvantages of using pesticides and biological control with crop plants

Biological control:

Is when and alien specie is introduced from another country to eat the pest.

An example of this is in Australia when the prickly pear cactus (pest) of north america was first introduced into gardens and escaped into the countryside and flourished under the Australian climate system. The cactus spread all over Australia into a good deal of agricultural land and it was necessary to get rid of it since there was no natural herbivore of the cactus. Therefore and alien specie was introduced for another country (a moth). This moth was introduced and had no competitors so they started to remove the prickly pear cactus.

Advantages:

• No toxic chemicals involved
• Less impact on man and wildlife   

Disadvantage:

• Not 100% effective
• Difficult to control (Danger that the introduced alien specie starts feeding on native species causing native species to diminish)
• Difficult to match predator to the prey (cant find predatory herbivores to remove the pest)