JOHANNESBURG, 9 September 2010 (IRIN) - The UN Food and Agriculture Organization (FAO) has warned of an "imminent and severe threat from the increasing number of swarms of Migratory Locusts" in Madagascar, requiring "immediate response assistance to prevent a humanitarian disaster".

The warning came at an Emergency Assistance to Locust Control meeting on 8 September in the capital, Antananarivo and a few days after USAID's Emergency Transboundary Outbreak Pest (ETOP) Situation Report for August with a Forecast till mid-October,  published similar concerns. 

"There is a likelihood of extensive breeding ... Should that occur, Madagascar will experience one of the most severe locust outbreaks in recent years, and will need to launch large-scale control interventions through mid-2011," ETOP said.

Dealing with the locust threat will cost about US$14.5 million; so far $4.7 million has been received from the UN Central Emergency Response Fund (CERF) and $490,000 from the FAO Technical Cooperation Emergency programme.

Annie Monard, the Rome-based FAO locust officer who will be arriving in Madagascar in the next few days, told IRIN that the indicators were of "serious concern", as the locust population was "so high" that they had been able to "escape the traditional area" [in southwestern Madagascar] and swarms had been observed along the east coast and in the whole mid-west.

A four-year locust plague ended in 2000, when only the far north of the world's fourth biggest island was spared from invasion by the Malagasy Migratory Locust (Locusta migratoria capito), and even the east coast, usually considered too humid, was affected.

This insect can produce a new generation almost every two months, and consumes roughly its own weight in vegetation - about two grams - every day. Monard said that while travelling in a helicopter in 1998 she looked down on a swarm covering an area about 30 km by 70 km. "It was like a huge cloud moving over the whole plain."

Undetected

The build-up of locusts occurred undetected during the previous rainy seasons (from October to April) while the capacity of the government's Locust Control Centre (CNA) was weakened as a result of the socio-political situation in the country, said an FAO document, Emergency assistance to locust control in Madagascar.

Madagascar has been enmeshed in a political crisis since 17 March 2009, with foreign aid cut to emergency humanitarian assistance, and only if justifiable, since the "illegal" transfer of power in which President Marc Ravalomanana stepped down in favour of opposition leader Andry Rajoelina.

The current prevailing dry, cool weather is unsuitable for breeding, but with the onset of the rains and higher temperatures, rapid reproduction occurs. As population density increases, the insects undergo behavioural and physical changes from solitary to gregarious, forming swarms that devastate crops - every million locusts eats one ton of food.

"The recently reported swarms outside their outbreak area indicate a major upsurge is on the rise. Past experience demonstrates that a plague could evolve if the locust population remains unchecked at this stage. The ensuing plague would persist for many years, with devastating consequences for food security," said the FAO emergency assistance document.

"Currently immature locust swarms will mature and start breeding at the onset of the next rainy season, and concentrations of wingless young locusts (hopper bands) will develop from October to December 2010. These bands will attack primarily the eastern parts of the outbreak area, which will receive the first rains. However, they will also affect the mid-west, which has been already invaded by swarms."

Monard said surveys and preparations had been undertaken since July this year to begin a spraying campaign ahead of the onset of the rains, using "three families of pesticides" to keep the insects in check.

Three families of pesticides

Conventional pesticides will protect threatened crops, Insect Growth Regulators will control hoppers [wingless locusts], and biological pesticides will be applied in ecologically sensitive areas, such as "natural reserves, national parks and populated areas", the FAO document said.

Spraying an estimated 500,000 hectares would take place when the locust populations were most vulnerable, and they "are not yet winged and less mobile, are marching, and at their most sensitive to pesticides," Monard commented.

However, equipment had to be pre-positioned ahead of the rains, as the roads to many areas threatened by locusts would become impassable during the rainy season, the FAO said.

FAO noted in its August Locust Response report that "The livelihoods of the rural communities, already precarious especially in the Great South [of Madagascar], are under immediate locust threat." Around 70 percent of Madagascar's roughly 20 million people live below the poverty line, and 50 percent of children under the age of five are malnourished.

Up to 52 communes in the region are predicted to be food insecure by the end of 2010, and 10 of these - containing around 100,000 people - are seen as acutely food insecure, according to an evaluation by the World Food Programme in July 2010. All the food insecure communes are threatened by locust swarms.

The CNA said more than 460,000 rural households, or 2.3 million people, would be affected by locust invasions, and potential crop losses could amount to at least $135 million.