The risks that stem from a failure to identify pests accurately are to be spelt out to a scientific workshop in Cardiff, the Welsh capital.

The meeting, from 22 to 29 August, brings together more than 250 taxonomists from 100 countries.

They are all members of BioNET International, set up six years ago to help developing countries to improve their competence in identifying and understanding the world's biodiversity.

'Sustainable conservation'

BioNET was founded by Professor Tecwyn Jones of Cardiff University, who argues that human well-being depends on understanding other forms of life.

"We need to know what these organisms are and how they interact with one another and with us so that we can conserve and manage them in a wise and sustainable way."

One example the workshop will hear about is the so-called mealybug introduced accidentally into Africa from Latin America in the 1970s.

It attacked cassava crops, reducing harvests by as much as 84%.

Scientists who imported predator wasps from Latin America to kill it were puzzled when after five years the problem was as bad as ever.

Wrong wasps

Then they found that the bug was native not to the whole of Latin America, but only to Paraguay and Bolivia.

They imported wasps from there, released them from aircraft over the cassava-growing area of central Africa, and quickly brought the bug under control.

But the five-year delay in identifying it, BioNET says, cost £1,500m in crop losses and pest control measures.

Getting the measure of a beetle matters

A similar mistake occurred with the large grain borer beetle, which was transported in the 1970s from the US to Tanzania in shipments of food-aid maize.

It was intercepted at the port of entry, Dar-es-Salaam, but was misidentified as the bamboo borer, an inoffensive beetle already found in Tanzania.

BioNET says the grain borer has caused crop losses amounting to hundreds of millions of pounds in east Africa, and also in the west, where it entered through shipments of maize to Togo.

But an insect called the pink hibiscus mealybug, an Indian native which reached the Caribbean island of Grenada in 1995, was stopped in its tracks by BioNET.

Its experts found two natural predators, a ladybird and a wasp, which meant the losses caused by the bug were limited.