"The desert locusts pose a very serious threat to the food security of the country," Ibrahim Abdullah Thabet, assistant FAO representative for the country, told IRIN in Sanaa, the Yemeni capital.
He stressed the importance of the upcoming spraying activities which would employ both helicopters and trucks to tackle what has been described as the worst infestation of its kind in the Arab peninsula nation in almost 15 years.
"The rural people affected are already quite poor. Any infestation of the vegetation in this area would certainly undermine the livelihoods of up to 9,000 local families," Thabet said.
The move follows an appeal for help earlier this month by the government's Desert Locusts Control Centre (DLCC), a unit regarded as under-resourced to respond to the current infestations as well as to additional breeding.
"Our capabilities are very limited and are designed to tackle locally bred locusts only. If things get worst we will definitely need aerial support," Abdu Farei al-Rumaih, the DLCC's director-general, told IRIN on 13 June.
Favourable breeding conditions
This year's desert locust problem has proven particularly bad after unusually heavy rains around the Horn of Africa and the interior of Saudi Arabia and Yemen, providing favourable conditions for the locusts to breed.
FAO has reported simultaneous locust outbreaks in Eritrea, northern Somalia, Saudi Arabia, Sudan, and more recently, in Yemen.
According to an assessment by FAO in collaboration with the DLCC, widespread breeding was already in progress in a large and remote area of around 30,000sqkm on the southern fringe of what is referred to as Yemen's Empty Quarter, which received extraordinarily heavy rains in March, making the chance of new swarm formations imminent.
Additionally, the current generation of new adult locusts would mature during June and would likely lay eggs by the end of the month, while at the same time there was the risk that any new swarms not controlled in the interior of Saudi Arabia might move south into Yemen's interior.
During July, hatching and band formation would occur, and swarms would form in August, while breeding could continue into the autumn even in the absence of further rainfall, the survey added, making the decision to spray all the more vital.
Eradication campaign to start 28 June
The three-month campaign, financed to the tune of US$2.6 million and targeting the adjoining eastern provinces of Hadhramaut, Shabwa and al-Mahra, two of which also border Saudi Arabia and Oman, is set to begin on 28 June, covering between 60,000 to 90,000 hectares over a 31,000sqkm area.
"If the locusts swarm around these areas, this year's harvest will be lost," Thabet warned. By the last quarter of the year, unchecked locust swarms could move into the country's highlands, as well as onto the Red Sea and Gulf Aden coastal plains - areas viewed as the country's most important agricultural areas, he said.
Although Yemen imports around 75 percent of its food needs, anything that might impact upon the country's limited agricultural areas - estimated at between just 1 and 2 percent of the country's land mass - would undoubtedly lead to a sharp price increase on domestically grown food, and could also badly affect local livelihoods, the FAO official said.
According to the UN, Yemen is classified as one of the least developed countries in the world, with 30-40 percent of Yemeni households impoverished, depending on the definition applied.