How Predators Can Boost Profits

If you are like many farmers, you use a spray programme because it gives you peace of mind. Yet, in many cases, you can have protection and peace of mind without the cost of spraying, which, of course, includes the expense of the chemical and running a tractor.

- Bill Kerr

When the leaf miner Liriomyza huidobrensis arrived in South Africa, it initially caused havoc, as it came after being subjected to many insecticides and had acquired resistance to most of them.

Today, however, a number of parasitoids can keep L. huidobrensis under control. But this means that farmers need to be very careful about what products they spray on crops attacked by this pest. One farmer I visited pointed to a tractor with a trailer making its way between the lands and said that before the leaf miner arrived, the tractor had been used solely for crop spraying. It would cover every land with insecticide, which would take a week; another chemical would be added the following week.