22 November 1996

Alien pests may bring bio-control boom

A RAPID rise in foreign pest species caused by increased global trade, coupled with the rising importance of integrated pest management, could see demand for biological control rocket in the next decade.

Alien pests can be particularly severe, since they often leave their natural predators behind, says Jeff Waage of the International Inst-itute of Biological Control, Ascot.

The deliberate introduction of those predators to the newly-colonised areas can be highly effective, reducing losses and removing the need for recurrent pesticide application. There are also health, environment, and market spin-offs, Dr Waage adds.

But only about 10% of cases fully succeed. Others achieve partial control, and in over a third of cases selected natural enemies have failed to establish altogether, he says.

Answers are needed. Greater reliance on biological control features in an international commitment made at the Rio Earth Summit to integrated pest management, says Dr Waage. Reasons are both environmental and economic – excessive traditional pesticide use can lead to serious pest outbreaks and production swings.

Work in the USA is studying how to improve success using natural predators of cereal aphids. K Hopper of the United States Department of Agriculture believes better decision making during biological control introductions will help. He is experimenting to discover what limits establishment and the efficacy of natural enemies. These include the selection of natural predators, their culturing and production and release and evaluation.

For example, many questions remain on collection of predators. The more genetically diverse the predator pool, the more likely it is to adapt to a new environment. "Should one collect a few insects from many countries or collect more from fewer locations?" &#42