RSTV: IN DEPTH- LOCUST ATTACK
Introduction:
In recent weeks, locust swarms have attacked crops in more than a dozen countries in Asia and Africa. The United Nations says the situation is extremely alarming in three regions – the Horn of Africa, the Red Sea area, and southwest Asia. The Horn of Africa is the worst-affected area. Locust swarms from Ethiopia and Somalia have reached south to Kenya and 14 other countries in the continent. In the Red Sea area, locusts have struck Saudi Arabia, Oman and Yemen. In southwest Asia, locust swarms have damaged in Iran, Pakistan and India.
Huge swarms of locusts have struck border villages in Rajasthan, Gujarat and Punjab – causing heavy damage to standing crop prompting state governments to sound high alert against locust attacks.
Locusts:
- They are a collection of certain species of short-horned grasshoppers in the family Acrididae that have a swarming phase.
- These insects are usually solitary, but under certain circumstances they become more abundant and change their behaviour and habits, becoming gregarious.
- No taxonomic distinction is made between locust and grasshopper species; the basis for the definition is whether a species forms swarms under intermittently suitable conditions.
- These grasshoppers are innocuous, their numbers are low, and they do not pose a major economic threat to agriculture.
- However, under suitable conditions of drought followed by rapid vegetation growth, serotonin in their brains triggers a dramatic set of changes: they start to breed abundantly, becoming gregarious and nomadic (loosely described as migratory) when their populations become dense enough.
- They form bands of wingless nymphs which later become swarms of winged adults. Both the bands and the swarms move around and rapidly strip fields and cause damage to crops.
- The adults are powerful fliers; they can travel great distances, consuming most of the green vegetation wherever the swarm settles
Is this the first time that locust has stayed in India after October-November?
- This has happened for the first time since the 1950s. The decades before this witnessed terrible and long periods of locust plague (when there is a swarm attack for more than two continuous years, it is called plague). This time, they stayed for long because of good monsoon.
- In 2019, monsoon started six weeks before time (first week of July) in western India, especially in locust infested areas. It also lasted a month longer — till November, instead of the usual September/October. Extended rains created excellent breeding conditions for the locust, while also producing natural vegetation on which they could feed longer.
- Locust came to Jaisalmer in May end. Rajasthan has witnessed three generations of breeding instead of the regular one generation. The first two generations caused a lot of damage to crops. The third generation is weak now.
How big is the number after the third generation?
- Locust breeds fast. The first breeding causes a 20-time increase in number; the second a 400-time rise; and the third 16,000 times.
- The peak infestation this time was in October, at the end of second generation, when large swarms were reported in Rajasthan and Gujarat.
- Since natural vegetation dried out in December, the swarms got into cultivated areas and caused damage.
Relationship between locusts and and climate change:
- During quiet periods—known as recessions—desert locusts are usually restricted to the semi-arid and arid deserts of Africa, the Near East and South-West Asia that receive less than 200 mm of rain annually.
- In normal conditions, locust numbers decrease either by natural mortality or through migration.
- However, the last five years have been hotter than any other since the industrial revolution and since 2009.
- Studies have linked a hotter climate to more damaging locust swarms, leaving Africa disproportionately affected—20 of the fastest warming countries globally are in Africa.
- Wet weather also favours multiplication of locusts. Widespread, above average rain that pounded the Horn of Africa from October to December 2019 were up to 400 per cent above normal rainfall amount.
- These abnormal rains were caused by the Indian Ocean dipole, a phenomenon accentuated by climate change.
How can countries and individuals be better prepared:
- While climate change is a global phenomenon, Africa stands out for its vulnerability which is driven primarily by the prevailing low levels of socioeconomic development. Persons living in poverty face compounding vulnerabilities to climate change impacts because they lack the resources to quickly recover from its effects.
- In this case, desert locusts are ravaging crops in the field before harvesting, wiping out livestock and wildlife feed, and with them savings, assets and livelihoods.
- Deployment of climate action solutions such as decentralizing solar dryers to agro-value chain actors can ensure that they can earn up to 30 times more by being able to preserve their harvest and sell during the offseason or gives them flexibility to compensate for unpredictable events such as these locust swarms.
- It can also create enterprise opportunities for auxiliary value chains of fabricating these solar dryers. Interventions like this are critical to increase climate resilience for some of the most vulnerable communities across the continent.
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.
