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Locust attacks

Topics Covered: Major crops cropping patterns in various parts of the country, different types of irrigation and irrigation systems storage.

Locust attacks

What to study?

For Prelims: What are locusts, how they affect crops? Affected countries.

For Mains: Concerns, effects, challenges and ways to address them.

Context: Locusts normally arrive during July-October, but have already been spotted in Rajasthan. At a time India is battling Covid, they present a new worry with their potential for exponential growth and crop destruction.

What are locusts?

Locusts are a group of short-horned grasshoppers that multiply in numbers as they migrate long distances in destructive swarms (up to 150km in one day).

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.).

How do they inflict damage?

  • 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.
  • 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.

How seriously should the first sightings of the locusts be viewed?

There’s nothing much to worry right now, as the rabi crop has already been harvested and farmers are yet to commence plantings for the new kharif season.

Besides, these have been low-density nymphs in “2nd to 4th instar” stages or immature winged adults. No breeding or swarm movement has also been seen so far.

The timing, though, is cause for concern. The normal breeding season for locusts in India is July-October. But this time, they have been sighted by mid-April. They could, nevertheless, breed to high enough populations for forming swarming and wreaking havoc during the rabi season.

How can locusts be controlled?

  • Controlling desert locust swarms primarily uses organophosphate chemicals by vehicle-mounted and aerial sprayers, and to a lesser extent by knapsack and hand-held sprayers.
  • Extensive research is ongoing regarding biological control and other means of non-chemical control with the current focus on pathogens and insect growth regulators. Control by natural predators and parasites so far is limited since locusts can quickly move away from most natural enemies.
  • While people and birds often eat locusts, this is not enough to significantly reduce population levels over large areas.

Sources: Indian Express.