Agricultural and defense ministers from western and northern Africa are gathering in Senegal to try to work out ways to deal with a locust scourge that the United Nations says is the worst to hit the continent in 15 years.

Senegalese President Abdoulaye Wade organized the meeting to address the increasingly dire situation caused by the locust plague that has hit North and West Africa.

The session follows a one-day meeting headed by the U.N. Food and Agricultural Organization (FAO), which is calling for greater measures to be implemented to battle the locusts.

An FAO expert, Keith Cressman, says donors have been contributing to the fight but much more needs to be done.

"Well, obviously we need to increase the current control operations that are in progress in the affected countries," he noted. "Most of those control operations are ground-based at the moment. We need now to shift to aerial control operations, primarily because the infestations are large enough to justify aerial control, and this is the most effective means of treating such large populations."

Mr. Cressman says the locust populations have soared because abundant rains are providing conditions for rapid breeding of the insects. He says the United Nations is especially concerned about the effect the locusts will have on countries that are almost entirely dependent on agriculture for survival.

"The country, for example, such as Mauritania, nearly the entire population is dependent on agriculture," he said. "And that country, in particular this year, is quite vulnerable because they've had a number of years quite recently in which the rains have not been so good and their agricultural production has been lower than normal. So this year, of course, the rains have been very good in the affected countries. That is good for the farmers, because it allows them to plant the crops, but at the same time we have a more significant threat to these crops because of the current locust situation in these countries."

The countries hit the hardest include Mauritania, Mali, Senegal, Niger, Chad, Burkina Faso and the Cape Verde islands.

Mr. Cressman says the desert locust swarms are not likely to affect countries along the Gulf of Guinea, such as Benin, which has organized its armed forces to protect its borders from the locusts.

But he warns that next month new swarms will form that could return to the original breeding grounds in northern Africa such as Western Sahara, Morocco, Algeria, Tunisia, and Libya.