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One way of controlling them is to find predators or parasites
which will kill them. This is called BIOCONTROL, because we are
using our understanding of their biology to control them. The predators
and parasites are called biocontrol agents.  Biocontrol
is used as a pest control strategy because 1.pest control is achieved forever with little or no more to be done 2. it is safe for humans and the environment 3. it is inexpensive in the long term (for every dollar spent on research into biocontrol, there is an economic benefit of thirty dollars).  Biocontrol
is not always used because 1.it is expensive to set up (cost of research) 2. no biocontrol agent can be introduced into Australia if they attack non-pest organisms. Such biocontrol agents cannot always be found. 3. pests are controlled satisfactorally using other control strategies Go to Careers to meet some people who are looking for biocontrol agents right now! Rabbit News Biological Control of Insects Examples of Biocontrol |
The parasitic wasp Encarsia formosa is an important biocontrol agent
of the whitefly, which is a widespread pest in glasshouses. The
Encarsia female lays her egg in the whitefly larvae which turn black
as the young wasp larvae develops. 
Prickly pear cactus was a problem in Australia earlier this century.
By 1925 an estimated 24 million hectares had been infested, mostly
in Queensland. Scientists searched through Mexico, United States
and Argentina for insects which would feed on the cactus and control
it's spread. A shipment of 2750 eggs of the moth Cactoblastis cactorum
was received from Argentina in 1925. By 1926, 2.5 million eggs had
been produced and 2.25 million were released into the field. Mass
destruction of prickly pear was evident by 1930, because the larvae
of Cactoblastis (see diagram on left) were eating the cactus plants.
Now, there are very few colonies of prickly pear left and most are
eventually found by Cactoblastis and destroyed. 
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