At a time when India is grappling with Covid-19, a locust crisis is swarming over northern parts of the country, with several states issuing advisories to prevent a desert locust attack.

With India battling the worst desert locust outbreak in three decades, the crop-destroying insects have now spread to Punjab, Gujarat, Maharashtra and Madhya Pradesh after arriving in Rajasthan.

In its latest update, the United Nations’s Food and Agriculture Organisation (FAO) desert locust information center said much of these movements were associated with strong westerly winds from the Bay of Bengal.

According to the Locust Warning Organisation (LWO), which monitors locust swarms, there is no immediate danger of the swarms heading towards Delhi.

The insects feed on a large variety of crops. If not controlled, locust swarms can threaten the food security of a country.

History of outbreaks:

While legend has it that locusts were part of the Mahabharata during Karna’s battle with Arjuna, modern-day records suggest that since the beginning of the 19th century, there have been at least eight “outbreaks” in India from 1812 to 1889, and a ninth in 1896-1897.

According to history of the Locust Warning Office published by the UN Food and Agriculture Organization (FAO), there were “serious invasions” of locusts in India every few years during the 1900s.

A “five-year invasion” from 1926 to 1931 is estimated to have to have damaged crops worth Rs 2 crore (about $100 million at today’s prices).

What are ‘desert locusts’ doing in non-desert lands:-

Desert locusts (Schistocerca gregaria), which belong to the family of grasshoppers, normally live and breed in semi-arid or desert regions.
For laying eggs, they require bare ground, which is rarely found in areas with dense vegetation.
So, they can breed in Rajasthan but not in the Indo-Gangetic plains or Godavari and Cauvery delta.
But green vegetation is required for hopper development. Hopper is the stage between the nymph that is hatched from the eggs, and the winged adult moth. Such cover isn’t widespread enough in the deserts to allow growth of large populations of locusts.
As individuals, or in small isolated groups, locusts are not very dangerous. But when they grow into large populations their behaviour changes, they transform from ‘solitary phase’ into ‘gregarious phase’, and start forming ‘swarms’.
A single swarm can contain 40 to 80 million adults in one square km, and these can travel up to 150 km a day.

What damage have they caused:-

So far, not much, since the rabi crop has already been harvested, and farmers are yet to really start kharif sowings.

The UN Food and Agriculture Organization (FAO) has, however, predicted “several successive waves of invasions until July in Rajasthan with eastward surges across northern India right up to Bihar and Odisha”.

But after July, there would be westward movements of the swarms that will return to Rajasthan on the back of changing winds associated with the southwest monsoon.

The danger is when they start breeding. A single gregarious female locust can lay 60-80 eggs three times during its average life cycle of 90 days. If their breeding is coterminous with that of the kharif crop, we could well have a situation similar to what maize, sorghum and wheat farmers of Kenya, Ethiopia and Somalia experienced in March-April.

How can these pests be controlled:-

Historically, locust control has involved spraying of organo-phospate pesticides on the night resting places of the locusts.

The Indian Institute of Sugarcane Research, Lucknow, advised farmers to spray chemicals like lambdacyhalothirn, deltamethrin, fipronil, chlorpyriphos, or malathion to control the swarms.

However, the Centre had on May 14 banned the use of chlorpyriphos and deltamethrin. Malathion is also included in the list of banned chemicals but has been subsequently allowed for locust control.

Special mounted guns are used to spray the chemicals on the resting places and India has 50 such guns, and 60 more are expected to arrive from UK by the first week of June. Drones are also being used this year.

Beginning of cooperation:-

Iran too suffered locust attacks, in 1876, and in 1926-1932.
“Apparently the first case of collaboration between countries in the region occurred in 1942 when a delegation from India helped with locust control work in southwest Persia.
Over the next two years, Indian help was also provided to Oman and Persia. This was followed by the first conference within the region on Desert Locust, which was held in Tehran in 1945 and involved Iran, India, Saudi Arabia and Egypt. A second conference took place in 1950 also in Tehran with Pakistan participating,” the FAO says.
In the 1950s, India and Iran cooperated and Pakistan provided two aircraft for locust surveys in Saudi Arabia.
Following another attack during 1958-61, a decision was taken to group Iran, Afghanistan, Pakistan and India together and the FAO Desert Locust commission was formed in 1964.
The commission held annual sessions, skipped in 1965 and 1999 but held in 1971. Even in the last six years when the relationship between India and Pakistan has deteriorated, it has been held in 2014, 2016 and 2018.

Damage and mitigation:

However, humans have a distinct advantage in fighting locusts now as compared to their ancestors — deeper knowledge and technology.
Farmers have switched to crops that can be harvested much before swarming season, and the locusts themselves can be controlled and killed with pesticides.
Monitoring for locust breeding is essential as it is much easier to destroy eggs than fully grown locusts.
At present, the primary method of controlling desert locust swarms is through organophosphate chemicals (the prime ingredient in herbicide and pesticide) applied in small concentrated doses by vehicle-mounted and aerial sprayers along with knapsack- and hand-held sprayers.
In rural areas of India, farmers have been known to beat steel utensils during late afternoons and evenings, and play loud music at night and create wood-fire, to ward off locust swarms from farms, albeit temporarily.
Additionally, newer technology in the form of serotonin inhibition has shown promise in laboratory settings.
 

Way Ahead:

As the current locust swarms attacking crops in India have bred and matured in Iran and Pakistan, New Delhi has offered assistance to both the countries to jointly combat the locust menace.

However, only Iran has accepted the offer so far. The External Affairs Ministry has approached state-owned HIL for the manufacture and supply of the pesticide Malathion Technical to Iran.

Monthly meetings are held between June and October-November at Zero Point, west of Barmer, Rajasthan and east of Chor, Tharparkar.

Arrangements are made in advance and protocols are followed for crossing the border.

While politics and diplomacy is kept out of the technical discussions, locust control authorities feel that one of the more difficult challenges faced by the commission is that of “insecurity and sensitivities” in the region.