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Locust Plague

  May 25, 2020

Locust Plague

Why is it in the news?

  1. A massive locust attack of December 2019 has affected about 25,000 hectares of land in two of the worst-hit North Gujarat districts of Banaskantha and Patan.
  2. On April 11-12 2020, scientists at the Locust Warning Organisation (LWO) observed groups of grasshoppers at Sri Ganganagar and Jaisalmer districts of Rajasthan. But far from ordinary hoppers, these were desert locusts — the same destructive migratory pests currently devouring acres of maize, sorghum and wheat crops in East Africa.

What are the locust attacks?

Locusts are a group of short-horned grasshoppers that multiply in numbers as they migrate long distances in destructive swarms. The swarms devour leaves, flowers, fruits, seeds, bark and growing points, and also destroy plants by their sheer weight as they descend on them in massive numbers. The desert locust (Schistocerca gregaria), is a polyphagous feeder (eating a large variety of plants). 

Nature and Occurrence:

  1. Desert areas of Rajasthan, Gujarat and Haryana are prone to swarms.
  2. From May to November, when desert locust activity is considered at its peak due to the congenial breeding conditions. This coincides with the monsoon season in Rajasthan and Gujarat.
  3. The locust menace is a natural occurrence which varies in intensity every year. The locusts remain inactive during evening and morning.
  4. Most swarms enter Gujarat through Rajasthan and Pakistan, riding on the wind to travel across large distances. 
  5. India is most at risk of a swarm invasion just before the onset of the monsoon. The swarms usually originate in the Arabian Peninsula and the Horn of Africa.
  6. The climate and the wind directions provide support to the locust movement and allow them to spread.

The extent of the damage:

The locust division under the Union Ministry of Agriculture & Farmers’ Welfare, says that a small swarm of locusts eats on average as much food in one day as about 10 elephants, 25 camels or 2500 people.

Tracking the locusts:

  1. In January 2019, the first locust swarms left to Yemen, Saudi Arabia, and south-west Iran, where heavy rains were reported, as per the FAO. Between February and June, widespread spring breeding in Yemen, Saudi Arabia and Iran caused the formation of large numbers of locust swarms.
  2. Control operations were less successful in Iran and Yemen and swarms invaded the India-Pakistan border between June and December.
  3. In India, the extended monsoon provided a favourable environment for the locusts to multiply.
  4. Each locust lays about 150 eggs. In fact, they lay eggs only in moist soil, therefore, when they arrived in India, the locusts multiplied uncontrollably because of the extended monsoon here.

The track followed by Locusts- FAO

What are the crops attacked by locusts?

Kharif crops like Groundnut, Castor and Cotton and Rabi crops like Mustard, Cumin and Wheat had been impacted along with Potatoes. The desert locust is a polyphagous feeder hence poses a danger to a large variety of crops/plants. 

Where does locust swarm originate?

India is most at risk of a swarm invasion just before the onset of the monsoon. The swarms usually originate in the Arabian Peninsula and the Horn of Africa.

What is a Locust Plague?

When there is a swarm attack for more than two continuous years, it is called a plague. With locusts already visible in Rajasthan, India is heading towards a Locust Plague this year.

What is the link between climate change and the locust attack?

Wind patterns are changing over India and Pakistan. Because of climate change in the Indian Ocean, there are more cyclones. The frequency of cyclones has increased. Usually, there are cyclone every five to six years, but in the past three years, there have been three cyclones each year. Cyclones bring rain to coastal Gujarat, Pakistan, Arabian Peninsula, Somalia and north-eastern Africa. This creates good breeding conditions. History shows that these locust plagues spread due to cyclonic winds.

What are the chemicals used to contain them?

Hazardous - highly toxic chemical - 96 per cent malathion, and Chlorpyrifos (CPS) 20 per cent and 50 per cent for sprayers. The Government of India deploys teams to control locust swarms, which spray a chemical called organophosphate in small, concentrated doses.

How does India monitor locust swarms?

The Locust Warning Organization (LWO) (comprising of all field units), a Central Government body responsible for issuing warnings and monitoring and controlling locust attacks, undertakes regular surveys in the scheduled desert area of Rajasthan, Gujarat and Haryana, which are prone to swarms, to monitor the presence of desert locusts and ecological conditions. These surveys are done regularly during the entire year, but most importantly from May to November.

Why did locust last longer in the year 2019-2020?

This has happened for the first time since the 1950s. The decades before this witnessed terrible and long periods of locust plague (when there is a swarm attack for more than two continuous years, it is called plague). This time, they stayed for a long time because of the good monsoon. In 2019, the monsoon started six weeks before time (first week of July) in Western India, especially in locust infested areas. It also lasted a month longer — till November, instead of the usual September/October. Extended rains created excellent breeding conditions for the locust, while also producing natural vegetation on which they could feed longer.

Africa too witnessed one of its worst locust attacks last year. Is it related to India?

It is linked to the attack in India and Pakistan. It started in mid-2018 when the desert region of Saudi Arabia received heavy rainfall due to a cyclone. There was another cyclone in November, followed by rains in the Red Sea coast region. These nine months of breeding produced an enormous number of locusts. Some of them moved north, to Iran, and from there came for the spring breeding in India and Pakistan. Other swarms moved south, to Yemen, and in summer, crossed the sea to reach Somalia, to the Horn of Africa.

Which organization is responsible for monitoring the Locusts attack worldwide?

The Food and Agriculture Organisation (FAO) of the United Nations is the international agency that monitors and manages locust invasions. It says a swarm of locusts, which contains about 40 million insects, can eat the same amount of food in one day as 35,000 people, 20 camels or six elephants.

All locust-affected countries transmit data about attacks to the FAO, where the information is analysed in conjunction with the weather and habitat data and satellite imagery. The organisation also provides forecasts for locust attacks up to six weeks in advance and issues warnings for each country.