|Quiet Revolutionaries - A Look at the Campaign by Agricultural Scientists to Fight Hunger (World Bank)|
The next step was to go back to the fields and find the natural enemies of those mealybugs. Some sixty species of predators and parasites were collected and sent off to the International Institute for Biological Control in Britain to be examined and put in quarantine .You want to make sure you're sending over just the pure species. Parasites have parasites-hyperparasites and we don't want those in Africa. It gets complicated'" Bellotti said.
Fifteen "natural enemies" were eventually released for trials. Two top candidates emerged: a beetle that had trouble surviving the rainy season, and the eventual winner, the one that proved to be the most effective, a tiny wasp called Epidinocarsis lopezi.
"What does this wasp actually do to the mealybug?" I asked
"It injects its eggs inside the mealybug. Then the wasps hatch out and develop inside the mealybug."
"How long does it take the mealybug to die?"
"About fifteen to sixteen days. The wasp is very effective," he said, showing slides that graphically and grotesquely proved his point. Nature is raw, not only in tooth and claw.
In Cotonou, Herren and his team had to overcome many hurdles. They first had to mass produce thousands and thousands of the wasps. This couldn't be like any other biological control program that had existed before, Herren said. It meant costly "machines of stainless steel. One of them cost $10,000 and we had eight of them"as well as air conditioning.
His critics thought that all this wasn't appropriate technology for Africa, and 1 hey were highly nervous about the costs. "My view is that what is appropriate technology is what is needed. Africans are running jumbo jets, all sorts of sophisticated machinery," he said. Eventually he got the support of some donors who believed in his ambitious largescale plans.
He then had a struggle to kind enough scientists to hire to work on this mass production. He needed scientists who understood insect behavior -who understood, for example, that if you have too many insects in one small space, they stop copulating and reproducing. "It's not a very academic subject," Herren explained. There's no publications. You don't make a career with this."
Ground and Air Release
Then, they had to figure out how to release all these wasps over an area one-and-a--half times the size of the United States. To release them on the ground, scientists earned from 5,000 to 20,000 wasps in vials to a number of fields and let them go in batches usually about 100 kilometers apart. The wasps spread rapidly. After twelve months, the fields were checked again. If the wasps were still there if they had survived a dry and a rainy seasonthen they were declared " established" in that area. But ground release was not enough. Because of the vast distances to be covered, there obviously also had to be some sort of release from the air.
Herren got a plane it cost him $800,000 a year-and in eight months worked out an imaginative system. Up to 210 wasps were packed in each vialthey were first cooled so they didn't move around too much anti taken aloft. At the right moment, air pressure blew out the vials' stoppers, and the wasps were propelled through a tube and out the back of the plane.
"They weren't damaged by this?" I asked.
"There was a mortality," he said. "But only about 2 percent of the wasps were killed."
"How high were you above the ground when you released them?"
"We flew anything between three meters and 100 meters. We had a former Royal Air Force pilot and he really enjoyed mowing the cassava with his propellers.''
From Cotonou, the aircraft flew out to western and central Africa. Sometimes it was based in Nairobi so it could fly out and back to areas in eastern and southern Africa. When that happened, the insects had somehow to get from their laboratories in Cotonou to meet up with the plane in Nairobi. This was no fob for an ordinary courier service. Herren said The cargo was far too precios. So technicians flew on commercial airlines "carrying the bugs on their laps." The wasps had to be released as quickly as possible, as their life span is only about one week. With this wellorganuled method, "we were able to release insects in Maputo, Mozambique, thirty-four hours after they were packaged in Cotonou," Herren said. "And we went into areas where there was war, where there was shooting"
Success was immediate. The South American wasps certainly found Africa to their liking, settling and multiplying in twentyfive countries of the cassava belt-over 2.7 million square kilometers. There they went to work on the mealybugs and saved the cassava crop. "It's under control in nearly 90 percent of the area," Herren said. One economist estimated that for every dollar spent by the control program, an African farmer had $149 in increased food productivity.
In addition, Herren said the experts now had a scientific base for biological control, a proper record of what they had done. Studies in the past were hardly ever done, which was one of the reasons why biological control was "always pushed aside as a method that didn't work. Out of 100 attempts, maybe only twenty worked in the past," he said. "And no one could tell you why the 80 percent didn't work because no one had done the proper studies. Now we really understand the system."