Insects Enlisted as Low-Tech Soldiers in War on Pests

NOT all insects are harmful," says Dale Bottrell, head of the entomology division at the International Rice Research Institute (IRRI).

"The insects we want to attract are pest predators. They are the natural enemies of rice pests," Dr. Bottrell says.

If genetic engineering represents the high-tech edge of agricultural research, then "integrated pest control" could be called a low-tech effort to correct one of the damaging side-effects of the green revolution.

The green revolution increased the use - even dependency - on chemical fertilizers and pesticides. Many rice farmers in Asia turned to these chemicals to provide the nutrients needed to grow new high-yielding varieties and to protect their crops from pests.

But pests developed increasing resistance to various chemical pesticides. And many farmers, even though they had adopted the attitude that pesticides were critical to a healthy crop, could not afford pesticides.

In response, research is being done here at IRRI and elsewhere in Asia on field ecology.

The idea is to promote natural means of discouraging pests - taking advantage of predators that feed on rice pests, such as certain types of spiders. Nongovernment organizations have led the field-level crusade.

Work is also being done in the lab that could enhance these chemical-free methods of stopping pests. One experiment aims to attract the predators by breeding scents into rice plants.

According to Bottrell, evidence is increasing that the scent of a pest's host plant - in this case, the rice plant - plays an important role in attracting predators and parasites.

Bottrell and his staff employ a device called an olfactometer to determine which rice varieties are preferred by the pest predator. "We can use these varieties as the parents of new rice lines" that are likely homes to "natural pest-control agents that live in them and kill the rice pests," the scientist says.

These new strains of rice promise to save the farmer "money he might have spent on pesticides," Bottrell notes.

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