Since the mid-1960s, Egyptian potato production has expanded at an annual rate of 5 percent, with production in 1995 estimated at 2 million tons. During roughly the same period, consumption increased from 8 to 32 kg per capita. These increases have taken place in a region where there is no appreciable rainfall, and where all farmland must be irrigated. Egyptian farmers till fewer than 3 million hectares, mainly in the Nile River delta. And it is here, unfortunately, where growth in potato production has been accompanied by huge increases in the use of highly toxic insecticides to control the potato tuber moth, Phthorimaea operculella.

Egyptian farmers have tried toxic pesticides to control the potato tuber moth in the past, but with disastrous results. The Egyptian government has established strict controls on pesticide use, mainly to protect consumers. It now prohibits the use of DDT and parathion on potatoes, and has begun to screen for detectable levels of pesticides on market potatoes. In 1995, the health ministry intercepted a load of contaminated potatoes. Sales dropped sharply and farmers were left with large amounts of produce they could not sell.

IPM safer, more effective

Many delta potato farmers harvest two-and sometimes three-crops per year. The most damaging pest in both seasons-in the field or in storage-is the potato tuber moth. Its short reproductive cycle allows it to wreak havoc with the crop. The adult tunnels through the soil and lays its eggs on the tuber's surface. Larvae hatch 3 to 5 days later, then bore into the tuber. Within a week, the moth emerges as an adult, and the cycle begins again.

Safe biological control agents have been tested to replace pesticides. One of these is the granulosis virus (GV), which is specific to the tuber moth and kills no other insects. Egypt's Plant Protection laboratory now manufactures GV-based sprays and powders that farmers claim work better than pesticides.  New products have been especially popular for protecting stored tubers.

The Plant Protection laboratory has also found a strain of the soil-borne bacterium Bacillus thuringiensis (Bt) that is lethal to the tuber moth. The lab multiplies Bt spores to make biological sprays and powders. Biological control technology is so promising that the Egyptian government is reportedly investing US$1 million in a new production facility.

With conventional pesticides, farmers spray on a schedule regardless of the severity of the infestation. With biological controls, they spray only when necessary, using pheromone traps to determine pest populations in the field.

Whereas most pesticides kill on contact, GV and Bt sprays can take days. Trainers help farmers understand what to expect in on-site demonstrations.

"I didn't think this would work," one farmer said during a training session. "But now that I've tried it, I can see that it's better...." Another farmer agreed: "Even if it costs as much, it works better, and it's better for our health."