From ladybirds in rose gardens to monkeys patrolling palm plantations, biological pest control has long been hailed as nature’s answer to crop-destroying invaders. Instead of relying on chemical sprays or laborious hand removal, farmers and gardeners turn to a pest’s natural enemies to keep populations in check — sometimes it works with remarkable success, and sometimes with disastrous consequences.
What is biological pest control
Biological pest-control is the use of a pest’s natural enemy to eradicate it from crops, gardens and houses, and is an alternative to harsh chemicals or removal by hand.
There are three types of biological pest control:
- Importation (introducing a new enemy into an environment)
- Augmentation (the boosting of natural enemy populations)
- Conservation (where a habitat is modified to allow the enemy to thrive).
When has biological pest control worked?
There are many successful examples. Ladybirds have long been a popular control for aphids; cactus moths have been instrumental in constraining invasive prickly pears in multiple countries.
More recently, pig-tailed macaques in Malaysia have been found to be curbing rat populations in palm-oil plantations. The monkeys consume the fruit-hungry rodents at such speed that they are preventing significant crop losses.
Does biological pest control ever go wrong?
Oh yes – and spectacularly so. One famous failure was the introduction of cane toads to Australia in 1935, with the aim of controlling the beetles decimating sugar-cane crops. With would-be predators recoiling at their toxic skin, the toads started to multiply.
Today, they exceed 200 million and are highly destructive. To add insult to injury, there is no evidence that they had any impact whatsoever on the beetles.
