Armies of locusts swarming across continents pose a “severe risk” to India’s agriculture this year, the UN has warned, prompting the authorities to step up vigil, deploy drones to detect their movement and hold talks with Pakistan, the most likely gateway for an invasion by the insects, on ways to minimise the damage.

Locust attacks are known to cause a considerable drop in agricultural output. Authorities at the national plant protection office said the country was prepared and deploying a wide range of measures.

But large-scale invasions could still prove challenging given that India lacks equipment like large sprayer aircraft, experts said.

A moderate infestation from across the border chomped through crops in an estimated 300,000 hectares in Rajasthan and Gujarat in January. The authorities say they are preparing to conserve crops during the upcoming summer-sown kharif season, which is most at risk.

An upsurge in locust attacks since last year is being attributed to favourable breeding weather caused by a large number of cyclones in

East Africa. India, China and Pakistan face the most risk in Asia. Pakistan has already declared an agricultural emergency, according to an Indian official.

Locusts can fly up to 150km in a day and a one-square-kilometre swarm can eat as much food as 35,000 people, in terms of weight, in a single day, according to the Food and Agriculture Organization (FAO)’s Desert Locust Information Service bulletin.

In December last year, India held preparatory meetings with Pakistani teams on the India-Pak border in Munabao and Khokhapar in Rajasthan’s Barmer district, an official said.

“We are scheduling more talks with Pakistani representatives during the entire June to September kharif (summer-sown) season,” said KL Gurjar, deputy director at India’s directorate of plant protection. Gurjar was one of the participants at the border talks in December. A report of a senior locust forecasting officer of the FAO to the government noted that “swarms would be present in Haryana and Punjab, moving east towards Bangladesh similar to 1950 when there were devastating plagues that lasted up to 14 consecutive years.”

The locust upsurge is linked to climate change, UN secretary general Antonio Guterres had said in a global briefing at Addis Ababa on February 8. “Warmer seas mean more cyclones generating the perfect breeding ground for locusts. Today the swarms are as big as major cities and it is getting worse by the day,” he said.

“The situation remains extremely alarming in the Horn of Africa, specifically Kenya, Ethiopia and Somalia, where widespread breeding is in progress and new swarms are expected to form in the coming weeks,” an FAO alert issued to nearly 53 countries, including India, on February 24 said.

Heavy cyclones made for favourable breeding conditions also in the southern Arabian Peninsula for at least nine months (June 2018 to March 2019), allowing “three generations of breeding that was undetected and not controlled”, the FAO said.

Pest specialists are drawing on standard strategies, such as maintaining sufficient reserves of melathion, the principal insecticide, adequate vehicle-mounted sprayers and experimenting with drones for early warning. “If they invade by night, by morning you will find whole farms are gone. Large swarms can cover several districts,” said JN Thakur, a former chief of locust monitoring at the agriculture ministry.

According to Thakur, India has an experience of fighting the pest from two previous outbreaks, in 1950 and 1993, but the country lacks large insecticide-spraying aircraft, which are the most effective way of dealing with a large-scale crisis.

On February 25, agriculture secretary Sanjay Agarwal chaired a high-level meeting on desert locust control with officials from Rajasthan, Gujarat, Punjab and Haryana, the external affairs ministry and the Hindustan Insecticides Limited.

The Union government has decided to conduct awareness campaigns and training for farmers and officials from these states.