A spate of kidnappings and attacks by militias in northern Mali and Niger has forced governments there to halt locust monitoring work, but the threat of locust invasion this year is still deemed low by the Food and Agriculture Organisation.

“Normally both countries have national locust teams which are responsible for visiting desert areas to check if there is green vegetation and locusts,” said Keith Cressman, locust monitoring officer at the FAO in Rome. “This year in the [northern desert areas] of Niger and Mali it is not secure so in both countries, teams cannot get in to do their monitoring,”

In Mali, a locust monitoring team was one of the first victims of a spate of kidnappings in August by a group claiming to be Touareg rebels. “The kidnapping of army soldiers got more attention,” Cressman explained. “It is not known if the locust team has been released. After that the government recalled all survey teams to a safe area and stopped surveying, and the same is true in Niger.”

An invasion is nonetheless deemed unlikely by the FAO. “If there were sizeable swarms we would hear about it – locals would pass the information to the authorities and they would inform us,” Cressman said. “It takes at least half a year before locusts reach [dangerous-sized swarms] and usually by then we would expect to have had warning.” Monitoring has continued as usual in neighbouring Mauritania, but little breeding has so far been discovered.

Locusts are an annual threat to people's already fragile livelihoods in the impoverished Sahel region of West Africa. The tiny insects breed exponentially to form devastating swarms that can strip hundreds of square miles of farmland bare within hours.

Preventing locust invasions is much easier if the locust larvae can be found before they hatch and while swarms are still small. The monitoring requires teams on the ground as the signs cannot be discovered on the military satellite readouts used by locust monitors in the Sahel.

According to the FAO, most of the breeding typically happens in the northern desert regions of Mali, Mauritania and Niger. The normal locust breeding period in West Africa is from July to September or October, coinciding with the annual rainy season.

Wetter years can sometimes be equated with a greater threat of locusts. However, the FAO said that even though this year some parts of the Sahel have experienced torrential rains and unprecedented flooding, the northern Sahel areas where the locusts usually breed have experienced only average rainfall.

“What flooding has been reported, and confirmed by satellite data, shows most floods occurred south of locust areas, not in them. This could be important for the breeding of [less destructive] grasshoppers, but not locusts,” Cressman said.

The last time a major locust invasions happened in West Africa was 2004. Even though regional locust monitors had detected swarms forming in October 2003, it was not until the insects started wiping out crops in September 2004 that donors and national governments took action.