An upsurge of locusts in northern Africa may spiral into a plague that would devastate crops, the UN's Food and Agriculture Organisation has warned, as Spain joined the effort to combat the voracious insects.

Nine Spanish planes left for Morocco on Monday to spray insecticide across the land and kill the recent swarms. "It is a lot easier to control the plague in the desert than in Spain," Juan Pena, the head of the Spanish project, told El Pais newspaper.

However, experts have told New Scientist that fears that the swarms may hit Europe may be unfounded as this would require "unusual winds". Furthermore, locusts have never been known to thrive in Europe.

"The chances of the desert locust moving into Spain or anywhere in Europe and causing extensive damage to crops is extremely small," said Clive Elliott, senior officer of the UN's Food and Agriculture Organisation's locust and other migratory pests group.

A much greater worry is that the insects could breed to plague proportions and ruin the livelihoods of poor African farmers and affect food security. The last African locust plague lasted from 1986 to 1989 and struck 40 countries.

In 2003, exceptionally wet rainy seasons in the Sahel and northern Africa meant that the desert locust species (Schistocerca gregaria (Forskal)) was able to breed more generations of offspring than usual, leading to a population boom.

"It's important to control in terms of protecting crops in the Sahel and trying to prevent it from getting any bigger," Elliott told New Scientist. "Possibly this summer is the last chance to do so. Once it really gets going it's extremely difficult to deal with as the population gets larger and larger."

Previous plagues of the 1940s and 1950s lasted 10 or 15 years, and hit as many as 65 countries, says Elliott. "It would be fairly horrendous if we moved into that scale," he warns.

The north African countries currently suffering swarms - Morocco, Algeria, Tunisia and Libya - are making "tremendous efforts" to control the insatiable pests, he says. But because the locusts cover such a huge area, Elliott predicts that substantial numbers of swarms will escape and move back into the Sahel later in 2004.

Whether the locusts have another successful breeding round will depend on the summer rains in the Sahel, he said. But reports suggest the rains may have already started. "Then we would expect that by the end of 2004 that a full blown plague will have developed."

Topics