The recent observation of desert locust groupings in the Sri Ganganagar and Jaisalmer districts of Rajasthan has set off warning bells for authorities. This is due to the significant damage these insects caused to growing rabi crops in western Rajasthan and parts of northern Gujarat between December 2019 and January 2020. This article sheds light on the nature of these pests, their destructive potential, and the measures put in place to control them.
Understanding Desert Locusts
Desert locusts (Schistocerca gregaria) are short-horned grasshoppers differing significantly from common hoppers. The current surge of desert locusts can be traced back to the Mekunu and Luban cyclonic storms that hit Oman and Yemen in 2018, respectively. These storms transformed vast desert areas in remote parts of the southern Arabian Peninsula into lakes, creating an environment conducive for these insects to breed across generations undetected.
Distinctive Nature of Locusts
Locusts, mostly found in tropical regions, are powerful flyers. They stand out from ordinary grasshoppers through their ability to change behaviour, called gregarize, and form swarms capable of large-scale migration. Gregarization refers to the transition of solitary insects into a swarm due to rapid growth in population. Locusts usually appear during June and July, being most active from summer to the rainy season. They possess an impressive capacity to multiply, form groups, and migrate over large distances—up to 150 km per day under favourable conditions, they can reproduce and multiply up to 20 times in three months.
Threat to Vegetation: Potential for Devastation
Adult locusts can consume their own body weight in fresh vegetation each day. Small swarms can consume as much food as 35,000 people in a single day, posing a massive threat to crops and food security. If locust infestations are not detected and controlled promptly, they can turn into devastating plagues that take several years and hundreds of millions of dollars to control, having severe consequences on food security and livelihoods.
Control Measures: Mitigating the Locust Threat
Locust control includes destroying egg masses laid by invading swarms, trapping nymphs in trenches, using hopperdozers (wheeled screens that force locusts into troughs containing water and kerosene), deploying insecticidal baits, and applying insecticides to swarms and breeding grounds from aircraft. Organophosphate insecticides, like Malathion, have proven effective against locusts. The Food and Agriculture Organisation (FAO) provides information on the overall locust situation worldwide and offers timely warnings and forecasts to countries at risk of invasion.
Locusts in India: The Menace Across Borders
India is home to four species of locusts: Desert locust (Schistocerca gregaria), Migratory locust (Locusta migratoria), Bombay Locust (Nomadacris succincta), and Tree locust (Anacridium sp.). The swarm currently in India originated in Iran and entered via Pakistan. Their movement is aided by summer dusty winds blowing from the Arabian Sea, carrying these creatures from Sindh in Pakistan to western Rajasthan. The last significant locust outbreak reported in Rajasthan was in 1993. The Locust Warning Organisation (LWO) under the Ministry of Agriculture & Farmers Welfare takes responsibility for monitoring, surveying, and controlling Desert Locust in the Scheduled Desert Areas, primarily in Gujarat and Rajasthan.
Last Modified: February 7, 2024