Explainer: What is a locust plague
India’s farms are facing a significant threat from a swarm of millions of locusts that have migrated from Africa and have now been spotted in Rajasthan, Madhya Pradesh and Uttar Pradesh.
A GENETIC MARVEL
The desert locust is one of about a dozen species of short-horned grasshoppers. They are unique in the way that they change their behaviour – turning from solitary to “gregarious” or social insects that coalesce into a swarm and forage for food together.
WHERE DID THEY ORIGINATE?
This swarm originated in the Horn of Africa, where excess rains triggered a breeding boom. According to Indian experts, the swarm entering India now had another round of breeding in Baluchistan, Iran and Pakistan.
WHERE ARE THEY NOW?
Swarms have moved to Rajasthan, Madhya Pradesh and border areas of Uttar Pradesh. They migrated to Fazilka in Punjab from Pakistan before spreading to other states from there. The worst-affected districts are Barmer, Jaisalmer and Nagaur.
WHAT DAMAGE CAN THEY CAUSE?
The current upsurge is alarming in the Eastern Africa region. Over 25 million people will face acute food insecurity in the region in the second half of 2020. In Yemen, where locusts have been reproducing in hard-to-access inland areas, 17 million people may be impacted. A swarm of locust spread over a square kilometre can chew through food enough for 35,000 people in a day.
CAN THEY HURT HUMANS?
Locusts do not attack people or animals. There is no evidence that suggests that locusts carry diseases that could harm humans.
CAN THEY BE CONTROLLED?
They can fly as far as 150km a day, making them difficult to control. Locust swarms can cover extremely large areas, which can sometimes be extremely remote and difficult to access. FAO monitors locust swarms on a 24-hour basis and provides forecasts and early warning alerts on the timing, scale and location of movement. Traditional chemicals are used to control their numbers. Now nature-based biopesticides are also available as a less harmful alternative for controlling outbreaks.
WHAT HAPPENS NOW?
If we are not able to control them, the sub adults will come back to their summer breeding area in the Thar desert bordering Pakistan. If there are good rains, they will lay eggs and lead to a new generation of desert locusts migrating to India again in a few months.
MEASURES IN INDIA
The Locust Warning Organisation under the ministry of agriculture has a ground team of 50 people mainly to monitor and track the swarms; drones are 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.
STRENGTH IN NUMBERS
*40-80 million locusts are estimated in a swarm that spreads over 1 square kilometre
*These many locusts can ravage crops equivalent to the feeding need of 35,000 people in a day
*Their life span is between 3-5 months. They become hoppers after a month and can start laying eggs when they 60-70 days old
Source: Locust Warning Organisation, FAO, National Geographic