Science - October 27, 2005

Bugs instead of pesticides

Professor Joop van Lenteren applies his extensive knowledge of insect biology to select insects that eliminate pests in a natural way. His insects paved the way for a sharp decrease in the use of toxic pesticides all around the world, from Brazil to Indonesia. The Wageningen professor of entomology received the Koninklijke/Shell Prize for his life-long achievements for sustainable agriculture on 19 October.

Already in his very first project in the tropics Van Lenteren, who has been professor in Wageningen since 1983, learned valuable lessons about fighting pests. On hundreds of thousands of hectares cotton fields in Sudan, laid out by the British, large amounts of chemical pesticides were used to eliminate crop-damaging pests like leafhoppers. ‘On these flat lands, it was easy to spray from airplanes. But the pests did not go away, and the government asked for our help.’ Van Lenteren and his colleagues did field tests to see what would happen when no or less pesticides were used. ‘Three out of four pests disappeared. When toxic chemicals were not used, the natural enemies of the pests, other tiny bugs, were not killed and could thus do their job. I learned a very important lesson: fewer chemicals often mean fewer pests.’

Over the past thirty years, Van Lenteren has discovered a large number of bugs that are useful for getting rid of other bugs that are pests. What’s more, he did not just stay in the lab or behind his computer writing articles: he has worked hard to put biological pest control into practice. His work has resulted for example in the widespread use of the tiny parasitoid wasp Encarsia formosa in agriculture all over the world. The wasp kills whiteflies in tomato and cucumber.

In the Netherlands, a wide variety of insects such as the common ladybird are now bred and used in greenhouses and in the field against pests. In recent years Van Lenteren has also developed criteria for quality control of natural enemies and protocols for safe evaluation and importation of exotic species. He has travelled to many countries in South-East Asia, Africa and South America, where he works together with local scientists and farmers. Many of his PhD students (more than 70 in total) came from countries in the tropics.

The professor is keen to share his knowledge, but he also tells farmers and scientists that solutions can often be found close to home. ‘A few years ago I met Brazilian farmers near São Paulo who wanted to import Dutch bugs for pest control. I asked them why on earth they wanted to do this. Later we discovered that natural enemies of the pest insects were present nearby. They had not been discovered earlier because chemical pesticides had been killing them.’

Biological control of insect pests keeps the environment cleaner, but Van Lenteren is also motivated by the health benefits: fruit and vegetables without traces of chemical substances. ‘In South-America and the more developed Asian countries, biological pest control has made a breakthrough. But it depends on the type of crop. Farmers in the tropics are smart enough not to spray poison on their own vegetables, but do use pesticides on export crops like cotton.’ The professor wants to raise awareness among farmers, for example in Africa, together with the Food and Agriculture Organization of the UN (FAO).

Van Lenteren, who is also honorary professor at the University of Perugia and president of the International Organization for Biological Control of Noxious Animals and Plants (IOBC Global), is much more than a scientist. His colleague at the Entomology Group, Dr Joop van Loon says, ‘He is a very powerful ambassador for biological control worldwide.’ Van Lenteren has yet more ambitious plans for the 100,000 euros’ prize money that goes with the Koninklijke/Shell Prize. He wants to design a ‘seawater greenhouse’ for the desert. ‘We will desalinate seawater and use it for crops in the greenhouse and drinking water.’ His other great passion is teaching kids about Mother Nature. ‘Let them discover how an ecosystem works, which animals eat which animals. That way they learn to respect nature.’/HB