Explained: What is the locust plague and impact on India

Explained: What is the locust plague and impact on India

A man attempts to fend-off a swarm of desert locusts at a ranch near the town of Nanyuki in Laikipia county, Kenya, Feb. 21, 2020. | Source: REUTERS/Baz Ratner

India is still reeling under intense fire from the COVID-19 pandemic. Another pandemic started knocking the door. This time, it is not a virus but large enough to be seen by naked eyes and touched by a human hand. This is locust pandemic. It is inflicting damages across Western India. The situation is grim in Rajsthan and Gujrat and now swarming locusts are entering Madhya Pardesh which is considered to be the biggest attack in the last 27 years.

After continuing destruction through Iran, Pakistan locust swarm has entered India and the forecasting officers have already warned the country against experiencing the worst locust situations in decades. 

According to the Ministry of Environment, Forests and Climate Change, “Locust swarm from Pakistan has entered Rajasthan, Punjab, Haryana and Madhya Pradesh, threatening major damage to standing cotton crops and vegetables. Rajasthan is the most affected state. During the current year, the swarm of locusts has entered India earlier than their normal time of June and July. States are adopting various means for controlling the swarms.”

What are locusts and their life cycle

Locusts are a collection of certain species of short-horned grasshoppers. They are capable to form a gigantic swarm that can spread across miles and miles eating away crops and dreaded for enormous agricultural crop damages. The locust can live between three and six months, and there is a chance of 10-16 fold increase in locust numbers from one generation to the next.

Their life cycle is divided into four segments, i.e., eggs, nymphs, fledgelings, and adults. Each female locust can drill a hole in the ground and lay eggs in a pod at a depth of 2–10 cm. A single female will usually lay one to three egg pods provided ample green vegetation is available. Pods can be laid in a minimum of five-day intervals during summer or 10–14 days during autumn. These eggs are generally hatched for about two weeks. They undergo five moulting phases during 1-2 months. The fifth stage is termed as fledgelings. It takes almost two weeks for fledgelings to get their body hardened. During this early stage of adult life, the locust continually feeds on vegetation in order to store up the energy necessary for reproduction and flying. Adult locusts typically live about 10 weeks.

Behaviour Change

As locust population density grows higher, individuals undergo physiological and behavioural changes. This sudden crowding releases serotonin in their central nervous systems that make locusts more sociable and promote rapid movements and more varied appetite. This phase change is accompanied by changes in body shape and colour and in fertility, physiology and survival. Gregarious locusts are colorful, move faster, and are attracted to other locusts. They fly during the broad daylight. It is in this phase that locusts from the oppressive swarms that can blacken the skies and decimate crops. These changes are so dramatic in some species that the swarming and non-swarming forms were once considered to be different species.  Once the phase change occurred, the swarm can be as big as size as three times the size of New York.  

A desert locust swarm can be 460 square miles in size and pack between 40 and 80 million locusts into less than half a square mile. Each locust can eat its weight in plants each day, so a swarm of such size would eat 423 million pounds of plants every day. To put it into context, a swarm the size of Paris can eat the same amount of food in one day as half the population of France.

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Gregarious locusts (L) and solitary (R) were once thought to be different species | Source: BBC

Swarming

Swarming is a collective behaviour exhibited by particularly animals like of similar size which aggregates together.  Desert Locusts usually fly with the wind at a speed of about 16-19 km/h depending on the wind. Swarms can travel about 5-130 km or more in a day. Locusts can stay in the air for long periods of time. For example, locusts regularly cross the Red Sea, a distance of 300 km. In the past, there have been some spectacular and very long-distance swarm migrations, for example from North-West Africa to the British Isles in 1954 and from West Africa to the Caribbean, a distance of 5,000 km in about ten days in 1988. Solitary Desert Locust adults usually fly at night whereas gregarious adults (swarms) fly during the day.

History and spread of locusts across globe

Swarming locusts were always a menace for the human species. Though it doesn’t hurt physically, it consumes the crops at a rapid pace and leaves humans with the scarcity of food and resources. It has existed even before history. The threat of locusts is even mentioned in the religious text where the God of the Hebrews, says, “How long will you refuse to humble yourself before me? Let my people go, so that they may worship me. If you refuse to let them go, I will bring locusts into your country tomorrow. They will cover the face of the ground so that it cannot be seen. They will devour what little you have left after the hail, including every tree that is growing in your fields. They will fill your houses and those of all your officials and all the Egyptians—something neither your fathers nor your forefathers have ever seen from the day they settled in this land till now.” Aristotle also studied locusts and their breeding habits in 203 BC. He mentioned human epidemics following locust plagues which he associated with the stench from the putrifying corpses.

During the last two millennium, locust plagues continued to appear at irregular intervals with the main recorded outbreaks of the desert and migratory locusts occurring in Africa, the Middle East, South Asia, and Europe.

Recent outbreak started in East Africa in early 2020. Ethiopia, Kenya, Somalia and Uganda are among the most affected countries. Its rampage is expected to face more than 42 million people in those countries “severe acute food insecurity,” according to the U.N. Food and Agriculture Organization (FAO).

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Desert Locust situation update | Source: FAO

Control Initiatives in the India, Pakistan, and Iran

India has established a methodology to survey, monitor and controls emanating threats from the locusts. The organisation LWO (Locust Warning Organization) undertake locust surveillance & monitoring, and coordinate other stakeholders on locust situation. It also issues Bulletins, organising Border meetings and conducting a field survey. Besides, undertake control operations during locust upsurge/incursion.

India is also buying drones and specialist equipment to monitor the movement of locusts and spray insecticides to ward off a new outbreak. In addition, considering it a common regional problem, India has already proposed a coordinated trilateral control response to Iran and Pakistan. While Iran has given a positive response in accepting India’s proposal. Pakistan response is still awaited.

Pakistan’s Prime Minister Imran Khan has already declared a locust emergency in the country. Considering the seriousness of the situation, Pakistan has already begun its plague control operation with the help of China though. The country has reportedly donated around 300 tonnes of locust-control pesticide and 350 vehicle-mounted sprayers to Pakistan.

Vimal Kumar

Vimal Kumar is an education enthusiast. He strives to pen down the untangled whirlwind of mind.