The UN has warned West and North Africa to be alert to a possible plague of locusts, which could have potentially devastating impacts on the region's crops.

The UN Food and Agriculture Organization (FAO) issued the alert on Wednesday
(11 October).

In northwest Mauritania, locusts are beginning to grow in numbers and have been seen laying eggs that could begin to hatch next week.

FAO experts say the new infestations probably originated from undetected breeding over the past two months in Mauritania or adjacent areas of northwest Mali.

Ground teams in northern Mauritania have started control operations and have sprayed more than 400 hectares of infestations with insecticide.

Surveys of locust activity are currently underway in southern and central Mauritania, northern Niger and in the southern parts of Morocco and Algeria.

The FAO is arranging for a helicopter to arrive in Mauritania next week to survey larger areas once the eggs hatch.

The organisation's assistant director-general Alexander Müller says the current situation is an opportunity to field test environmentally friendly alternatives to conventional pesticides.

The FAO will conduct trials using a 'biopesticide' — a fungus called Metarhizium anisopliae — that stops juvenile locusts from feeding so that they die in one to three weeks.

During the summer of 2004, an outbreak of locusts devastated crops, fruit trees and vegetation in several parts of West Africa, at a cost of more than US$400 million.

By the summer of 2005, the upsurge had ended by a combination of control operations and unfavourable weather.