Climate Change

Locust attack: India faces worst-ever pest invasion

Apart from India, the pests have attacked 60 countries including Pakistan and Somalia, that have declared national emergencies

 
Last Updated: Wednesday 05 February 2020

India is suffering one of the worst locust attacks in its history. 

Desert or yellow locusts have raided several districts in Rajasthan and Gujarat. These pests entering from Pakistan had damaged standing crops over 370,000 hectares by January 12, 2020. Pakistan and Somalia have declared emergencies to control the pests.

Locusts are short-horned grasshoppers belong to the family Acrididae. They have big hind legs for jumping. Locusts differ from grasshoppers in that they have the ability to change their behaviour and habits and can migrate over large distances. They are capable of forming ‘swarms’ (adult’s congregation) and ‘hopper bands’ (nymphal congregation).

They live for 90 days and eat voraciously — the equivalent to their bodyweight every day. They feed on green, leafy plants and always travel during the day time. An average adult locust swarm eats as much as about 10 elephants, 25 camels or 2,500 people.

When conditions are favourable for reproduction, locust numbers increase 20-fold in three months. The favourable conditions for breeding include moist sandy or sand / clay soil to a depth of 10-15 cm below the surface, or some bare areas for egg-laying, and green vegetation for hopper development.

Locusts take 50 days to develop from eggs to an immature stage. The immature locusts take another 30 days to reach the egg-laying stage. Once egg laying is done, the insects die.

When conditions are not favourable, their numbers decrease either by natural mortality or through migration. It restricts itself to the semi-arid and arid deserts of Africa, west and south Asia that receive less than 200 mm of rain annually. This is an area of about 16 million square kilometres, consisting of about 30 countries.

In the current case, climate change-induced unseasonal rain or frequent cyclones have been considered to be the main reasons for the infestations. Apart from India, the pests have attacked 60 countries in two major continents, comprising 30 million sq km

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