In May 2020, the population explosion of swarms of desert locusts, Schistocerca gregaria became a cause of serious concern due to their Propensity to destroy crops. The swarms came from Didwana in Nagaur district and entered Jaipur through Kishangarh Renwal and Jobner. They moved towards Dausa without settling at any green patch, though a few groups landed on the roofs of some high-rise buildings. This huge locust swarms appeared in the skies of Jaipur, which were killed in Dausa district’s Kota Patti village, around 53 km from Jaipur with the spray of high-intensity malathion insecticide, which helped in killing almost the entire swarm of insects at the pasture land.
What Locusts Causes to Swarm
A study published in the journal, Nature, in August 2020, deals with the pheromone which is the main factor behind locust swarm. This study may help develop new methods to control locust outbreaks.
Locustia migratoria is considered the most widely distributed and one of the most dangerous locust species, which represents a serious threat to agriculture, the world over. As per the researchers, a small organic compound, called 4-vinylanisole (4VA) is released by gregarious migratory locusts. The molecule acts as a powerful attractant to migratory locusts of all ages and both sexes, and if four or five solitary locusts are housed together, they too begin to produce and emit the pheromone, which is detected by specific sensory cells, called basiconic sensilla. These are found in the locusts’ antennae. The molecule binds to a specific olfactory receptor, called OR35. Locusts engineered to lack this receptor are less attracted to 4VA.
If a synthetic version of 4VA was deployed in the wild, it could potentially be used to lure locusts into traps where they could be killed. Or, if a chemical that blocks the activity of the molecule was released, it might prevent the locusts from aggregating and migrating. However, more research is needed to the test these strategies.
The Schistocerca gregaria or the desert locust is a short-horned grasshopper that is harmless while it is in a ‘solitary phase’ and moves about independently. They differ from normal hoppers and become dangerous only when their populations build up rapidly. Close physical contact in crowded conditions triggers behavioural changes. They, then, enter the ‘gregarious phase’, i.e., group into bands and form swarms that can travel great distances up to 150 km daily, while eating up every bit of vegetation on the way. If not controlled, the insect swarms can threaten the food security of countries.
Locust Invasion in Subcontinent
The locust invasion started from the India-Pakistan border on April 11, and affected about 20 of 33 districts in Rajasthan, crossed the Thar desert and travelled far in search of food, taking advantage of favourable wind conditions with the onset of summer.
The UN Food and Agriculture Organization (FAO) had warned that locusts were breeding in large numbers in Sudan and Eritrea on Africa’s Red Sea Coast as well as in Iran. They travelled through Pakistan to enter the Indian side of Thar desert, which can fly up to 150 km in a day, and a 1 sq. km. swarm can eat as much food as 35,000 people in a single day in terms of weight.
Monitoring of Locust Swarms
Monitoring and tackling periodic outbreaks of the marauding insects are among the objectives of the Locust Warning Organisation (LWO) in Jodhpur. From 1964 to 1997, 13 locust upsurges were recorded, and but ‘no large-scale breeding’ was reported after 2010. Once a significant outbreak starts, it lasts for about two years, and then there is a quietus for about eight years. As per LWO officials, the latest swarm is potentially the ‘worst in decades.’
It is so devastating that an arcane piece of legislation, The East Punjab Agricultural Pests, Diseases and Noxious Weeds Act, 1949, has a provision whereby a District Collector can ask any male person not below the age of 14 years resident in the district for any possible help, the failure of which can lead to potential imprisonment.
Factors of Their Breeding up
According to some meteorologists, the breeding locusts are an indirect fallout of the warming Indian Ocean, Last year, there were fears that the monsoon may fall short because of warming of the Equatorial Pacific. But, by July, it was evident that a positive Indian Ocean Dipole, or relatively higher temperature in the western Indian Ocean, was in the works, which led to record-breaking rainfall in India and eastern Africa. The moist conditions in African deserts precipitated locust breeding and favourable rain-bearing winds helped them drive towards India.
Besides, routine coordination activities regarding spraying pesticides were halted due to Covid-19 in India, Pakistan, and Afghanistan. Global warming may also be one of the factor behind such upsurge.