The global upsurge of locusts is on the brink of becoming a plague, aided by unusually favourable weather for three years and the international community’s failure to curb their growth.
Swarms of locusts took Delhi and the National Capital Region by suprise on June 27, 2020, the first time since the locust plague of 1926-31, according to some estimates.
After spreading to Bihar, the insects have started mayhem in Nepal. By July 2, locusts spread to almost a dozen districts in the Himalayan country where the kharif crop cycle is underway.
Locusts have damaged transplanted paddy, maize, fodder grass and vegetables, according to Plant Quarantine and Pesticide Management Center in Nepal’s Lalitpur. Severe damage has been reported from Dang and Pyuthan districts.
While some swarms have stayed in the Kathmandu valley, some have headed further north towards Ramechaap.
In the past, locusts have invaded Nepal on rare occasions and only during plagues.
The Food and Agriculture Organization (FAO closely monitors the spread of locusts and plays a crucial role in its control operations. It said in a 2014 document that in Southwest Asia, locusts are normally present in southeast Iran and southwest Pakistan during the spring and along the Indo-Pakistan border during the summer.
“During plagues, locust swarms often migrate further north and east than usual … and occasionally invade countries on the southern edge of the former Soviet Union as well as Nepal and Bangladesh,” the document, The FAO Commission for Controlling the Desert Locust in South-West Asia, said.
“This [latest] spread is due to the southwesterly monsoon winds as well as the two days of strong southerly winds over Uttar Pradesh that carried desert locust groups to the northern districts and a few crossed into Nepal lowlands and scattered,” Keith Cressman, senior locust forecasting officer of FAO, said.
Earlier, between the last week of May and early June, when swarms of locusts unusually spread to states as far as Chhattisgarh in the east and Maharashtra in the south, FAO had linked it to the strong northwesterly winds established in the aftermath of the super cyclone Amphan.
Locust officers of India, who are working overtime to chase and destroy the insects, say the widespread invasion this year is also because of the sheer number of the swarms crossing over to India.
Despite control operations in spring-breeding areas, Cressman admitted that the swarms were the result of higher than normal levels of breeding this past spring in Pakistan and Iran. “They will breed in the summer until about October / November in Rajasthan,” he added.
But most locusts have already matured since their arrival as hopper bands or immature adults in India in April. Till mid-June, breeding was underway in Bikaner, Nagaur, Barmer and Jodhpur districts. They are now being joined by spring-bred swarms from Iran and southwest