What is the ecological principle behind the biological control method of managing with pest insects?

Explanation

he prickly pear cactus introduced in Australia in the early 1920s caused havoc by spreading rapidly into millions of hectares of rangel and (vast natural grass lands). Finally the invasive cactus was brought under control only after a cactus feeding predator (a moth) was introduced in the country. Biological control methods adopted in agricultural pest control are based on the ability of the predators to regulate prey populations.