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Published: 15th Feb, 2020


  • In recent weeks, locust swarms have attacked crops in more than a dozen countries in Asia and Africa.
  • The United Nations says the situation is extremely alarming in three regions - the Horn of Africa, the Red Sea area, and southwest Asia.
  • The Horn of Africa is the worst-affected area.
  • Locust swarms from Ethiopia and Somalia have reached south to Kenya and 14 other countries in the continent.
  • In the Red Sea area, locusts have struck Saudi Arabia, Oman and Yemen.
  • In southwest Asia, locust swarms have damaged in Iran, Pakistan and India.
  • Huge swarms of locusts have struck border villages in Rajasthan, Gujarat and Punjab - causing heavy damage to standing crop prompting state governments to sound high alert against locust attacks.

What is a Desert Locust?

  • The Desert Locust is one of about a dozen species of short-horned grasshoppers (Acridoidea) that are known to change their behavior and form swarms of adults or bands of hoppers (wingless nymphs).
  • The swarms that form can be dense and highly mobile.
  • The Latin name for Desert Locust is Schistocerca gregaria (Forskal).
  • Locusts, which are part of the grasshopper family, are highly mobile insects that can migrate across different countries and cause extreme damage to crops.

Which countries are affected by the global crisis?

  • The Food and Agriculture Organisation (FAO) of the United Nations has currently identified three hotspots of threatening locust activity, where the situation has been called “extremely alarming” — the Horn of Africa, the Red Sea area, and southwest Asia.
  • The Horn of Africa has been called the worst-affected area, where the FAO has said there is “an unprecedented threat to food security and livelihoods”.
  • Locust swarms from Ethiopia and Somalia have travelled south to Kenya and 14 other countries in the continent.
  • Ethiopia’s Rift Valley has also been hit by the pest.
  • The outbreak is the worst to strike Ethiopia and Somalia in 25 years, and the worst infestation in Kenya in the past 70 years.
  • Without international help, the FAO has said that locust numbers across the region could grow 500 times by June.
  • In the Red Sea area, locusts have struck in Saudi Arabia, Oman, and Yemen. The swarms are presumed to have arrived here from the Indo-Pakistan border area.
  • In southwest Asia, locusts swarms have caused damage in Iran, India, and Pakistan.

How do they inflict damage?

  • 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.
  • Four species of locusts are found in India:
    • Desert locust (Schistocerca gregaria),
    • Migratory locust (Locusta migratoria),
    • Bombay Locust (Nomadacris succincta) and
    • Tree locust (Anacridium sp.).
  • The desert locust is regarded as the most destructive pest in India as well as internationally, with a small swarm covering one square kilometre being able to consume the same amount of food in one day as 35,000 people.

Measures India has taken

  • India has a locust control and research scheme that is being implemented through the Locust Warning Organisation (LWO), established in 1939 and amalgamated in 1946 with the Directorate of Plant Protection Quarantine and Storage (PPQS) of the Ministry of Agriculture.
  • LWO’s responsibility is monitoring and control of the locust situation in Scheduled Desert Areas, mainly in Rajasthan and Gujarat, and partly in Punjab and Haryana.
  • Food and Agriculture Organisation (FAO) of the United Nations is the international agency that monitors and manages locust invasions.
  • FAO also provides forecasts for locust attacks up to six weeks in advance and issues warnings for each country.

What is the relationship between locusts and ecology?

  • When conditions are favourable for reproduction, locust numbers increase and when they are not, numbers decrease either by natural mortality or through migration.
  • For the Desert Locust, favourable conditions for breeding are
    • Moist sandy or sand/clay soil to depths of 10-15 cm below the surface,
    • Some bare areas for egg-laying, and
    • Green vegetation for hopper development.
  • Often favourable conditions may exist in the desert but there are no locusts present.
  • Therefore, the presence of moist soil and green vegetation does not automatically mean that there are locusts around.

How can locusts be controlled?

  • At present the primary method of controlling Desert Locust swarms and hopper bands is with mainly organphosphate chemicals applied in small concentrated doses (referred to as ultra low volume (ULV) formulation) by vehicle-mounted and aerial sprayers and to a lesser extent by knapsack and hand-held sprayers.

Why is Desert Locust so difficult to control?

There are many reasons as to why it is difficult to successfully combat the Desert Locust.

  • The extremely large area (16-30 million sq. km) within which locusts can be found,
  • The remoteness and difficult access of such areas,
  • The insecurity or lack of safety (such as land mines) in some areas,
  • The limited resources for locust monitoring and control in some of the affected countries,
  • The undeveloped basic infrastructure (roads, communications, water and food) in many countries,
  • The difficulty in maintaining a sufficient number of trained staff and functioning resources during the long periods of recession in which there is little or no locust activity,
  • Political relations amongst affected countries,
  • The difficulty in organizing and implementing control operations in which the pesticide must be applied directly onto the locusts, and
  • The difficulty in predicting outbreaks given the lack of periodicity of such incidents and the uncertainty of rainfall in locust areas.

What is the role of FAO in locust control?

  • One of the mandates of the Food and Agriculture Organization (FAO) of the United Nations is to provide information on the general locust situation to all interested countries and to give timely warnings and forecasts to those countries in danger of invasion.
  • Therefore, FAO operates a centralized Desert Locust information service within the Locust Group at FAO Headquarters, Rome, Italy.
  • All locust affected countries transmit locust data to FAO who in turn analyze this information in conjunction with weather and habitat data and satellite imagery in order to assess the current locust situation, provide forecasts up to six weeks in advance and issue warnings on an ad-hoc basis.
  • FAO prepares monthly bulletins and periodic updates summarizing the locust situation and forecasting migration and breeding on a country by country basis.
  • Furthermore, FAO provides training and prepares publications on various aspects of locusts.
  • FAO undertakes field assessment missions and coordinates survey and control operations as well as assistance during locust plagues.

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