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Locusts’ outbreak: Causes & Consequences

by Sanjenbam Jugeshwor Singh
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According to FAO, locusts and grasshoppers are short-horned insects like crickets and long-horned grasshoppers. They breed in exponentials numbers as they migrate long distances in destructive swarms even from one continent to another. In India, there are four species of locusts- desert locusts; migratory locusts; Bombay locusts and tree locusts. Human activity has made an Ocean circulation pattern misbehave-triggering a weird confluence of events that has caused the infestation. If there is slightly above normal rainfall and green vegetation develops, the insects can rapidly increase in numbers in a month or two. An outbreak usually occurs within an area of about 5000 sq.km (100 km by 50 km) in one part of a country. If an outbreak or contemporaneous outbreak are not controlled and if widespread or usually heavy rainfall in adjacent areas, several successive seasons of breeding can occur, causing further hopper band and adult swarm formations- called an upsurge. This can affect an entire region.
If an upsurge is not controlled and ecological condition continue to increase in number and size which can lead to plague. The last few upsurges lead to plagues. In India, the last major plague was in 1987-89 and last major upsurge was in 2003-05. The recent outbreak of locusts attack on Indian farmland occurred due to erratic rainfall in deserts of the Middle East in 2018 which created conditions conducive for locusts to breed. Abundant rain water gathered in different parts of the arid deserts over Saudi Arabia, Oman, the United Arab Emirates and Yemen after the region was hit by cyclone Mekunu in May 2018. It ended up creating favourable breeding conditions for deserts locusts. Locusts’ swarms are known to retreat by November every year, but longer seasonal rainfall in India has created favourable for locusts in the Thar Desert. The insect behind the mayhem are desert locusts, which despite their name, thrive following periods of heavy rainfall that trigger blooms of vegetation across their normally arid habitat in Africa and Middle East. Experts say, a prolonged bout of exceptionally wet weather including several rare cyclones that struck eastern Africa and Arabian Peninsula over the last 18 months (Cyclone Mekunu in May 2018 & Cyclone Luban in October 2018) are the primary culprits. The recent storminess( cyclonic storm-Pawan in December-2019),in turn is related to the Indian Ocean Dipole, an Ocean temperature gradient that was recently extremely pronounced something  that’s also been linked to the deva sting bushfires in Eastern Australia.  Two cyclones brought heavy rains to the Arabian Desert and help locust breed freely. Locusts spread out and breed more.
The insects not only causes immense damage to crops  on farmland by ravaging leaves, flowers and fruits but they also destroy plants just by their weights as they come in massive numbers. Even a small swarm of locusts engulfing an area of 1sq.km devours food in a day that can feed as many as 40,000 people as reported by FAO. File photo of 21st February 2020 shows swarm of desert locusts over ranch near the town of Nanyuki in Laikipai County of Kenya. According to FAO, desert locusts that are primarily responsible for an invasion across different agro-climate zone and crop damage are present somewhere in the deserts between Mauritania and India. India has been battling locusts’ attacks with moderate success since December. However, the onset of monsoon could bring more trouble. Several countries across multiple agro-climatic zones ranging from Africa, the Middle East to Asia are ruling under unprecedented locusts’ attacks. A warning-“Desert Locust Watch”- put out by FAO on 2nd March, has described the situation as extremely alarming, especially in Kenya, Ethiopia and Somalia. While India has also suffered from the locusts attacks, the country has for now brought the situation under control but only after substantial damage to crops in Rajasthan and Gujarat. India along with Iran and Pakistan falls in the southwest zone, which the UN’s FAO has identified as among the three flashpoints for locusts swarms. The other two include the Horn of Africa and the Red Sea zone. Of the three, the Horn of Africa has been the most severely hit by locusts swarm attacks to the extent that the FAO has described it as “unprecedented threat to food security and livelihoods”. Countries such as Ethiopia, Kenya and Somalia are among the 17 that have witness locusts attacks in the Horn of Africa. In the Red Sea Zone, locusts have damaged vegetation in Saudi Arabia, Oman and Yemen. In India, oilseed, cumin and wheat across nearly 1.7 lakh hectares of farmlands have been affected by locusts’ swarms, which come in from Pakistan through the border areas of Rajasthan and Gujarat.
Amid Covid-19 pandemic, India’s response to natural disasters is expected to be tested again this summer when a giant locust storm from the Horn of Africa is expected to attack farmlands in South Asia, starting from the Horn of Africa and joined by desert locusts from breeding ground en route. One locust stream can travel over a land corridor passing over Yemen, Bahrain, Kuwait, Qatar, Iran, Saudi Arabia, Pakistan and India, impacting farmlands in Punjab, Haryana and the Indo-Gangetic plain. But another stream passing over the Indian Ocean can directly attack farms in peninsular India and then head toward Bangladesh. Together, this can cause a serious food security issue. The destructive power of a typical locust swarm, which can vary from less than 1sq.km to several hundred sq.km is enormous as per the websites of FAO. The looming locust attack which could undermine food security in the Afro-Asian region, follows the economic devastation and savaging of income by the Covid-19 pandemic. Though, it’s almost impossible to exterminate a locust attack, the severity of it can be reduced by destroying egg masses laid by invading swarms. This involves using insecticides bait and spraying insecticides on both the swarms and their breeding grounds. As said, prevention is better than cure, so we must prepare now to face another invasion by locusts in our country.

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