Killing insects before monsoon crucial to halting second wave of locust swarms
Officials in three states are racing to control the desert locust swarms that have now spread to three states, adding to the logistical challenges of district officials at a time when containing the spread of the coronavirus disease (Covid-19) has been the top-most priority.
State and federal agencies need to eliminate as much of these locusts as possible prior to the arrival of monsoon, the point when the swarms could go through another round of breeding and turn into a bigger threat, said the Locust Warning Organisation under the Union agriculture ministry.
“If we are not able to control the sub-adults (the swarms that are already in MP and Rajasthan) they will grow into adults come back to the summer breeding sites along the Indo-Pak border in the desert. If there is good rainfall, moisture will make it conducive for egg laying in sandy soil. We may have to face a second generation of desert locusts then. If they are not controlled in hopper stage, then they turn into swarms that will again pose a challenge for us,” said KL Gurjar, deputy director, directorate of Plant Protection Quarantine and Storage, LWO.
The Food and Agriculture Organisation’s (FAO) situation update dated May 21 said spring breeding continues in southern Iran and southwest Pakistan where control operations are in progress against hopper groups and bands. As vegetation dries out, more groups and swarms will form and move from these areas to the summer breeding areas along both sides of the Indo-Pakistan border as several waves from now until at least early July. Good rains are predicted during the first half of June along the Indo-Pakistan border that would allow egg-laying to occur.
FAO’s forecast maps also show summer breeding in India and Pakistan in June. “There is also a possibility that they enter India directly from the Horn of Africa in July by crossing the sea with the help of winds. The situation is being continuously monitored,” added Gurjar.
According to FAO, favourable conditions for their breeding are moist sandy or sand/clay soil to depths of 10-15 cm below the surface, some bare areas for egg-laying, and green vegetation for hopper development.
The LWO has a ground team of 50 people mainly to monitor and track the swarms. Drones are being used for aerial spraying of Malathion 96, an organophosphate insecticide and a potentially toxic chemical for non-cropped areas. For areas with agriculture, chlorpyrifos is sprayed by drones, fire brigades and tractor mounted sprays. Farmers are trying to disperse them by making noise which is not very effective but can help. Spraying takes place very early in the morning before they start moving again. .
According to some assessments, the locust outbreak this time is linked to climate change. The World Meteorological Organisation earlier this year said unusually heavy rain in late 2019 was a factor in the severe desert locust outbreak in the Horn of Africa region. The outbreak was the worst in over 25 years, and the most serious in 70 years for Kenya. This is expected to spread further by June 2020 in a severe threat to food security.
Originally, the locusts began migrating from the Horn of Africa last year. They migrated from the Middle East to Iran, Pakistan and then into India.
“The outbreak started after warm waters in the western Indian Ocean in late 2019 fuelled heavy amounts of rains over east Africa and the Arabian Peninsula. These warm waters were caused by the phenomenon called the Indian Ocean Dipole—with warmer than usual waters to its west, and cooler waters to its east. Rising temperatures due to global warming amplified the dipole and made the western Indian Ocean particularly warm. Heavy rain triggers the growth of vegetation in arid areas where desert locusts can then grow and breed.
“These locusts which migrated to India early this year might have found greener pastures as the pre-monsoon rains during March–May were in excess over north India this year,” said Roxy Mathew Koll, climate scientist at Indian Institute of Tropical Meteorology.