Locust Invasion

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Context: The migratory insect – locust has swarmed the northern parts of Gujarat, causing significant damage to agriculture.

Prelims: Current events of national and international importance.
Mains: GS III- Major crops cropping patterns in various parts of the country- issues and related constraints.

What is Locust and how does it harm Agriculture?

  • Locusts are a collection of certain species of short-horned grasshoppers in the family Acrididae that have a swarming phase.
  • Locusts are generally seen during the months of June and July as the insects are active from summer to the rainy season.
  • When vegetation in the desert begins receding due to continuous drought, an intriguing and fearsome transformation takes place in the grasshopper.
  • Living so far in isolated niches in the desert, the grasshoppers crowd for food and shade into the small areas that still bear vegetation.
  • Close proximity with each other then causes an intriguing mutual excitation, inducing behavioural and physiological changes.
  • The grasshoppers' pigmentation changes from green to black, helping them to absorb more heat.
  • This leads to intense activity among them and, abandoning their solitary habits, they soon acquire an extremely gregarious nature.
  • They begin to move and feed together in bands, forming swarms that take wing for great distances in search of food.
  • Locusts have a high capacity to multiply, form groups, migrate over relatively large distances (they can fly up to 150 km per day).
  • They can rapidly reproduce and increase some 20-fold in three months.
  • The adults are powerful fliers- they can travel great distances, consuming most of the green vegetation wherever the swarm settles.
  • A very small swarm eats as much in one day as about 35,000 people, posing a devastating threat to crops and food security.
  • Locust swarms are the bane of farmers in more than 66 countries.
  • Locusts need moist, sandy soil in which to lay eggs and fresh vegetation for hoppers to grow into adults
  • A good monsoon is therefore always a cause for concern to locust authorities and farmers, who worry that a locust invasion could come just when their crops are doing well.
  • Swarms migrate according to seasonal rains and the prevailing winds to two widely separated geographic belts- the winter-spring breeding zone and the summer-autumn zone.

Locust Invasion:

  • Several species of grasshoppers swarm as locusts in different parts of the world, on all continents except Antarctica and North America.
    • For example, the Australian plague locust swarms across Australia.
  • The desert locust is probably the best-known species owing to its wide distribution (North Africa, Middle East, and the Indian subcontinent) and its ability to migrate over long distances.
  • A major infestation covered much of western Africa in 2003-4 after unusually heavy rain set up favourable ecological conditions for swarming.
    • The first outbreaks occurred in Mauritania, Mali, Niger, and Sudan in 2003.
    • The rain allowed swarms to develop and move north to Morocco and Algeria, threatening croplands.
    • Swarms crossed Africa, appearing in Egypt, Jordan, and Israel, the first time in those countries for 50 years.
    • The cost of handling the infestation was put at US$122 million, and the damage to crops at up to $2.5 billion.
  • Locusts come in large numbers, traversing continents and oceans. From time immemorial, desert locusts have journeyed with the winds in search of rain and food, moving rapidly and covering areas as extensive as 16.5 million sq km.
  • From the deserts of the Sahel and the arid zones along the Red Sea, they grow steadily in numbers and begin to spread across the Arabian Sea.
  • They fly at heights of up to two km and, aided by winds, can cover a distance of 2,000 km at one stretch.
  • Travelling in bands as dense as 12,000 per sq km, they eventually land on the shores of the Indian subcontinent, their arrival coinciding with the southwest monsoon.
  • By this time, the monsoon showers have coaxed greenery out of the inhospitable Thar desert and this becomes a veritable feast for the exotic visitors.
  • Crops that grow fast and full to the farmer's delight- sometimes after years of drought- and thriving bushes of fodder grass: every speck of green is food to these invading hordes of hungry desert locusts.
  • Although the Sahel and the Arabian Peninsula are the major breeding grounds of the desert locust, it is also indigenous to India.
  • Small populations exist in the Thar, but seasonal upsurges in their numbers can usually be brought under control.
  • In the recent Locust Invasion, originally, the locusts emerged in February this year from Sudan and Eritrea on Africa’s Red Sea Coast and travelled through Saudi Arabia and Iran to enter Pakistan.
    • From there they invaded the Sindh province and from then moved into Rajasthan and Gujarat.
    • As the swarms mature, they have ravaged farms in North Gujarat, devastating farmers in the three border districts Banaskantha, Patan, and Kutch.
    • The locusts, known as tiddis locally, have wreaked havoc on standing crops of castor, cumin, jatropha, cotton, and potato, and fodder grass in around 20 talukas.
    • Gujarat has not witnessed such an invasion of locusts since 1993-94.
  • The UN Food and Agriculture Organisation (FAO) had issued an alert of a massive locust attack in South Asia covering Pakistan and India.
  • According to the Agriculture Ministry’s Locust Warning Organisation (LWO), locusts are flying in from Pakistan’s Sindh province and spreading in villages in Rajasthan and Gujarat where southwestern monsoon had prolonged this time.
Locust Warning Organisation (LWO), Directorate of Plant Protection Quarantine and Storage, Ministry of Agriculture & Farmers Welfare, is responsible for monitoring, survey and control of Desert Locust in Scheduled Desert Areas mainly in the States of Rajasthan and Gujarat.

What can be done?

  • Historically, people could do little to protect their crops from being devastated by locusts, although eating the insects may have been some consolation.
  • By the early 20th century, efforts were being made to disrupt the development of the insects by cultivating the soil where eggs were laid, collecting hoppers with catching machines, killing them with flamethrowers, trapping them in ditches, and crushing them with rollers and other mechanical methods.
  • By the 1950s, the organochloride dieldrin was found to be an extremely effective insecticide, but it was later banned from use in most countries because of its persistence in the environment and its bioaccumulation in the food chain.
  • In years when locust control is needed, the hoppers are targeted early by applying water-based, contact pesticides using tractor-based sprayers.
    • This is effective but slow and labour-intensive, and where possible, spraying concentrated insecticide solutions from aircraft over the insects or the vegetation on which they feed is preferable.
  • The use of ultralow-volume spraying of contact pesticides from aircraft in overlapping swathes is effective against nomadic bands and can be used to treat large areas of land swiftly.
  • Other modern technologies used for planning locust control include GPS, GIS tools, and satellite imagery, and computers provide rapid data management and analysis.
  • Dried fungal spores of a Metarhizium acridum sprayed in breeding areas pierce the locust exoskeleton on germination and invade the body cavity, causing death.
    • The fungus is passed from insect to insect and persists in the area, making repeated treatments unnecessary.
    • This approach to locust control was used in Tanzania in 2009 to treat around 10,000 hectares in the Iku-Katavi National Park infested with adult locusts.
    • The outbreak was contained and the elephants, hippopotamuses, and giraffes present in the area were unharmed.
    • The ultimate goal in locust control is the use of preventive and proactive methods that disrupt the environment to the least possible extent.
    • This would make agricultural production easier and more secure in the many regions where growing crops is of vital importance to the survival of the local people.

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