Bug Wars.(The Talk of the Town)

Kari Heliovaara is the head of forest entomology at the University of Helsinki and the co-author of a standard text, entitled "Insects and Pollution." A Finn, he has nonetheless spent a good deal of the past decade working in China. "Control strategy"--how to stop insects from killing trees--is one of Heliovaara's areas of expertise, and he was recently part of a team hired to prevent an ongoing eco-catastrophe from marring the Olympics in Beijing.

For years, a blight had ravaged nearly all the deciduous trees in Beijing, leaving the branches naked and ugly. Civic leaders were worried, in the run-up to the Games, what the bare trees would say about their city's environmental problems. So, a couple of years ago, they approached the Beijing Forestry University and the Chinese Academy of Forestry and asked if a way could be found to put the leaves back. The Chinese experts--many of whom had worked with or studied under Heliovaara--turned to the Finn for assistance. Heliovaara signed on, and, after he and the scientists discovered that the larvae of moths and sawflies were causing the problem, he helped launch a project called Green Beijing.

"Chemical control was possible but ecologically not recommended," Heliovaara said the other day. "Precisely planned biological control is much more effective." Biological control, in this context, means rearing parasites that attack only the defoliating pests. "This is very challenging, and is based on a high level of taxonomic know-how, " he went on.

He explained how to create an antidote to an infestation: "First, you catch a female moth by net. Second, you catch a male moth using either natural female pheromones or artificial pheromones as a lure. The female moth mates with the male and produces eggs. After a few days, larvae hatch. Then the larvae are infected by parasitic wasps. This is where taxonomic knowledge is crucial. You need to infect the larvae with exactly the correct kind of parasite."

Heliovaara is, in many respects, a typical Finn, wry and dry and proud. He owns a boat, and, in the summer, sails the Baltic with his family. But nothing excites him as much as talking about ...