|Quiet Revolutionaries - A Look at the Campaign by Agricultural Scientists to Fight Hunger (World Bank)|
Originally, tibe biological control program was based at the International Institute of Tropical Agriculture (IITA) in Ibadan, Nigeria the sister organization to CIATbut soon Herren and his scientists needed more space. So in 1988 they moved their laboratories just across the border to Cotonou in Benin. Another reason for moving was that operating the aircraft from Nigeria had been frustrating. Herren said with a grin: "In Cotonou you just go to the airport and say, 'I'm going to Senegal,' arid you go. You don't have to do three days of paperwork ahead of time, to get in and out."
They were granted diplomatic status right away, allowing them free movement, whereas the scientists who remained in Nigeria received theirs only in 1991. Other scientists commented that the move was also made because Nigeria was becoming too expensive at that time and a bit lawless, and they wanted to decentralize because Nigerian concerns were dominating the Institute's projects to the detriment of other African countries.
Eastward Out of Africa
As for the future of the saga of man versus the cassava mealybug, the pest is obviously not going -to stay still. It moved into Uganda, for example, causing crop devastation right away, Herren said. So they kept a small production capacity going "to fight these new little flare-ups." And, certainly, it will eventually move eastward out of Africa and into Asia.
"It stops now at Africa's Indian Ocean coast But it'll move. It
came from South America to Africa. It'll go around the world. It'll go to
Madagascar, sooner or later," Herren said. "'Comoros. Then Mauritius."
"How will it move there?"
"Probably on gifts that families give to each other."
"Wouldn't it be possible to keep Madagascar, for example, somehow free of the pest?',
"You can have strong quarantine regulations, but you can't always catch the odd guy crossing in a little boat."
"And then it'll move to cassava-growing areas in Asia, such as India and Thailand?"
"But because of your biological control program, it can be fought in these new places?" Exactly" Everything is ready."
But the scientists can't rest on their laurels. "It's not something you solve once," explained Bellotti." "It's something you've got to keep on top of." And, of course, the mealybug is not the only (albeit the most devastating) pest that damages cassavathere's also the hornworm, the green mite, thrips, burrowing bugs, shoot flies, fruit flies, whiteflies (which spread a disease called mosaic), whitegrubs, cutworms, termites, ants, midges, stemborers, and grasshoppers, to name only some.
Enter the Hornworm
The hornwormits scientific name is Erinnyis ello-is unlovely and voracious. When it's a caterpillar, it chews on the leaves and can completely defoliate a crop, causing a loss of root yield of as much as 20 percent. The farmers in the Americas who can afford pesticidesits a pest in the Americas this time rather than in Africa-use sprays, but usually do that when they notice that the leaves are almost all gone.
"And then it's too late?" I asked Bellotti.
"It's then usually too late."
The strategy is to try and come up with an alternative to pesticides, which can harm the environment. The hornworm, like the mealybug, has lots of different natural enemies (there are about forty of them), including one wasp that simply "cuts up the hornworm like a piece of meat and takes it back to its nest to feed to its young" But why, if it has all these natural enemies, was it continuing to cause such havoc? Why wasn't it being controlled?
The insect is migratory," Bellotti explained. "The moths can fly hundreds of kilometres and can fly in mass. We've captured three to four thousand in one light trap in one night. When these adults come intens of thousands in one nighthere's a tremendous outbreak, and natural biological control isn't going to be good enough Migration has become a defense mechanism. They can migrate, for example, from the Atlantic coast of Costa Rica to the Pacific coast, back and forth." So the scientists had to look elsewhere.
They found the answer in a disease, a virus that is highly lethal to the hornworm. Spreading the disease turned out to be not too difficult. At least, Bellotti made it all sound as simple as mixing a cocktail.
"You take some diseased hornworms and stick then, in a blender.
Or you can just leave them in a rnayonnaise jar and a liquid will slowly ooze
out " He opened the door of a refrigerator which stood in the corner of his lab,
and pointed to a jar.
"That liquid has the virus disease in it" An innocent-looking milky substance was collecting on the jar's bottom.
"You use the blender just to speed the process up?"
"Sure. Then you add water and put it into a spray tank That's all you need. A back spray, and you apply it like any other insecticide."
"The virus slowly kills the hornworms. It breaks the cellstructure."
"Over some weeks?"
"No. In a matter of a flaw days. Almost 100 percent mortality "
"It sounds too good to be true."
"It's used now a fair amount in southern Brazil. It's being introduced into northeast Brazil and here in Colombia It's reducing pesticide use on cassava by about 60 percent. This is a different type of biological control-but it's very common and very important."