I have a biology assignment and we have to explain various methods and strategies for conservation, two of which are:

Biological control
Introduced Species

What is the difference between these? I was under the impression that they are essentially the same thing – biological control being the introduction of species to predate pests (eg. the abysmal failure of the cane toad).

Any clarification would be great.


2 Answers 2


After talking to my teacher, he said that biological control is the introduction of species to control another species, however species may be introduced for other reasons (the "Introduced Species" method), such as to "assist an ecosystem cope, flourish or re-establish itself."

The example he gave was the introduction of South African veldt grass to Western Australia in order to stabilise sand dunes, so that they can later be built upon further (eg. plants which may not perform well in sandy, unstable soil can then be planted).

Hopefully this helps anyone else with the same problem.


Biological control does not have to be with an introduced species. It can also be accomplished by either artificially inflating the number of existing predators.

E.g. Spruce bud worm has a natural predator in the form of a tiny wasp. But budworm can spread through a stand faster than the wasp can. By moving popluatins of the wasp to the forefront of the budworm advance, you get most of the 2nd generation budworms. The trees have a bad needle year but aren't killed.

It can also be done with habitat modification. If you create conditions that favour the existing predator, then there are more predators in place. E.g. create places for ladybug overwintering to reduce aphid populations. (I have no idea if this would work.)

Anohter example -- although ecological controll may be better than biological -- I had a significant mosquito problem. Lots of small puddles in spring. I created a permanent pond. This has resulted in much smaller mosquito population.

  • The pond is a local year round water supply for insectivorous birds.
  • The pond is by far the largest water body around, so tends to get most of the mosquito eggs.
  • The pond now has a permanent population of boreal and chorus frogs. Tadpoles of these make it tough to be a mosquito larvae.

Is this species introduction? Only if you consider immigrant species from neighborin populations to be introduction.


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