Chemical residues may cause harm to humans, especially farmers.
This has lead to the development of Biological control methods. This is a method of pest control that uses other organisms that are predators or parasites of the pest to reduce pest numbers to low levels at which there is little economic damage.
What are the advantages of biological control?
It is usually highly specific to a particular pest.
Although expensive to introduce (mainly due to research costs), it can be very cheap in the long term.
It can provide a long-term solution to a pest problem
There is no environmental contamination.
Pests do not become resistant.
What are the disadvantages of Biological control?
Successful examples are not all that common and mainly confined to ‘glasshouse pests’ and pest problems located in small areas, often on islands.
Research and development costs can be high.
The introduced species may have unknown ecological effects, and even become a pest itself. e.g. the cane toad and the harlequin ladybird.
The pest can remain in small numbers and to keep its damage to a level which is not economically damaging, frequent input is needed to maintain a population balance between predator and prey.