'Indian Jones' of the insect world: Hans Herren
Entolomogist might just have saved half of Africa
By Barry Shlachter
IBADAN, Nigeria - Call him the Wasp Man of Africa.
Hans Herren's name is probably unknown to the 200 million Africans whose staple food crop, cassava, he saved from a devastating pest. Cassava (pronounced kuh-SAH-vuh), from which Americans produce tapioca, provides half the caloric intake for people in 25 African countries.
Before Herren began his work, 80 percent of Africa's cassava production was threatened. Widespread starvation was feared and though a major crisis appeared imminent, the drama unfolded with practically no attention from Western news media.
The 45-year-old Swiss entomologist, after lengthy detective work, bred and dispersed countless tiny, stingless wasps that are harmless to humans but deadly to the cassava-destroying mealybug. The pest was contained two years ago in the largest project of its kind, and isolated outbreaks are still squelched by Herren's one-sixteenth-inch wasps.
In saving Africa's crop, Herren underscored his admitted preference for "biological control": attacking a pest with its natural predator instead of applying chemical insecticides or breeding resistant strains of food crops.
"Nothing of that magnitude had been done before," said Professor Fowden Maxwell, 61, head of Texas A&M University's entomology department, in a call from College Station. "Herren's work with the cassava mealybug is one of the bigger success stories in biological control. But generally, the public is not aware."
But Maxwell is not totally uncritical of Herren, whom he calls a "very outspoken, aggressive individual" of the "classical, die-hard" school of biological control.
Herren's approach works well on certain crops, such as buffalo grass in Texas, Maxwell said. But in most cases, specialists increasingly endorse "integrated pest management," which combines biological control with plant resistance, anti-pest farming techniques and, where necessary, safe insecticides that target a specific pest, he said.
In the case of the cassava mealybug, Herren argued that finding the predator of a destructive insect would be quicker and cheaper than developing hybrid crops and would be less risky to the environment than chemical pesticides. Moreover, it would save millions of imperiled people.
The trick was identifying the pest and then locating its natural enemy.
Like an Indiana Jones of insect science, Herren made five three-month forays through Central and South America, where cassava had originated, trying not to let guerrilla ambushes and counterinsurgencies slow his search for the elusive mealybug.
"Eight hundred times I was told, `Hands up!' Army troops mistook my boots for those worn by parachutists and thought I was a guerrilla," he said.
"I found all kinds of mealybugs - I have two species named after me - but never the right one."
Before returning to West Africa, Herren asked an American friend, entomologist Tony Bellotti, to be on the lookout. On a visit to his ex-wife in Paraguay, Bellotti found an unfamiliar mealybug. He sent a specimen to the British Museum in London, which identified it as Phenacocus manihoti, and it proved to be fortuitous.
"Now we found the needle in the haystack," said Herren, who had done postgraduate work at the University of California at Berkeley.
But much detective work lay ahead.
Having identified the culprit, researchers cut open live mealybugs and found deadly parasites: wasps and ladybugs. The most numerous was called Epidinocarsis lopezi, which had been discovered in Argentina, and Herren realized he had the pest's natural enemy.
In November 1981, using a glass vial with honey and blotting paper and stopped with cotton, Herren flew the tiny wasps to Nigeria, where he hoped to breed the parasite quickly and somehow release it across the continent to wipe out the scourge.
The wasp finds the mealybug by smell. After sweeping it with antennae, the wasp injects an egg into the bug like a syringe. The resulting larva then eats the mealybug's innards until it dies - a "slow, cruel death taking five days," Herren said. Then a full-grown wasp emerges within 14 days from the "mummy" shell of the slain mealybug. During a weeklong lifespan, it can inject the lethal eggs into 70 to 140 bugs.
After identifying the mealybug's natural enemy, Herren still had to find money for a five-year, $30 million project "I dreamed up," he said. The plan envisioned a 3-story breeding tower for the wasps, three aircraft to release them and one supply plane.
At the start, all he got was $250,000 from a U.N. agency - and he was lucky. "People said, `This guy is crazy, a megalomaniac,' " he recalled. "I almost got fired three times."
Herren's employer, the Ibadan-based International Institute for Tropical Agriculture, was highly skeptical of his biological control ideas. Its own bias was toward breeding hardy new strains, which triggered the 1960s Green Revolution, which made India and Mexico self-sufficient in food.
The outspoken Swiss was considered heretical for questioning an approach advocated by such luminaries as Nobel Prize-winning scientist Norman Borlaug, now an A&M professor, who developed the high-yielding "miracle" grain crops.
"I had just arrived from Berkeley, and they thought, `Here's another eco-freak from California,' " the bearded Herren recalled during a visit to IITA's headquarters inNigeria from his home in neighboring Benin. "I had to fight the institution, which wanted to breed in resistance, reflecting the work of Borlaug. They were narrow-minded and, in places, still are."
Herren complained that insect-breeding techniques "were 100 years behind the times. And we had to find something fast and big because people were starving," he said.
He scaled back his project, requesting - and getting - $6 million over three years.
"In Zambia, after a year, entire fields of cassava plants were dead - all white, full of mealybugs," Herren said. The bug can kill 100 percent of a field's cassava plants by sucking out the sap and depositing a leaf-killing toxin. By 1980, it had spread from the Congo to Senegal, Nigeria and Benin.
Inspired by a hydroponics tower at Epcot Center in Orlando, Fla.,, similar to those growing tomatoes in the desert, Herren built a 12-foot-high model that bred zillions of his E. lopezi wasps.
The first generation was allowed to multiply and then Herren sucked up the offspring with a modified Black & Decker Dustbuster. After a whiff of carbon dioxide put them out cold, the wasps were transferred to vials holding 50 to 100 each for dispersal on the ground.
The first South American wasps were released in November 1981 on the IITA campus in Nigeria. Five months later, "the mealybug population just collapsed. There were no mealybugs left," Herren said.
When the pest disappears in an area, so does the otherwise harmless wasp, because it can lay eggs only in mealybugs, he said.
Armed with a successful test result, the entomologist went elsewhere in the West African nation to disperse his wasps and then to Zaire and Senegal.
"Suddenly, we couldn't respond to all the requests," Herren said. "Countries started standing in line waiting for the wasps."
To speed things, Herren's team developed a device to blow the tiny wasps from a twin-engine Beechcraft, once used by the CIA in southeast Asia, and now flown earth-huggingly low by a pilot who had worked for the British Royal Air Force.
When government officials initially opposed the plane's use as "not being appropriate technology," Herren, in his typically pragmatic but abrupt way, replied, "What's appropriate is what works."
It did work.The plane was used in nine countries of West, East, Central and Southern Africa. The only nation to reject Herren's wasps- as "too risky" - was Cameroon, which benefited anyway when the insects blew across the border from Nigeria and Gabon.
Herren is credited not only with preventing widespread starvation, but also with doing it cheaply.
Unlike many foreign aid projects that have little to show after millions are spent, Herren's cassava mealybug project will save an estimated $149 in ruined crops over 25 years for every $1 spent, the American Journal of Agricultural Economics said recently.
From 1989, Nigeria alone dramatically increased cassava production from 15 million tons to 40 million.
And Hans Herren, the Wasp Man of Africa, has moved on to using nature's own agents against other bugs - among them an age-old scourge, the locust.
[Herren, recipient of the 1995 World Food Prize, became president of the Washington-based Millennium Institute.]
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