Locust Attacks in India: Causes and Management (UPSC Environment)

Locusts are a collection of short-horned grasshopper species in the family Acrididae that undergo a dramatic shift from solitary, harmless insects to dense, migratory swarms capable of wiping out crops across entire regions. The desert locust (Schistocerca gregaria) is the most damaging species for India. The 2019–2020 desert locust upsurge — the worst in 27 years — reached 10 Indian states including Rajasthan, Gujarat, Madhya Pradesh, Punjab and parts of Uttar Pradesh and Maharashtra, causing significant crop damage and national concern.

The FAO describes the desert locust as the world's most destructive migratory pest. A single swarm of 1 square kilometre can contain 40–80 million locusts and consume food equivalent to what 35,000 people eat in a day. Large swarms can travel up to 150 km a day on wind currents.

Biology of Locusts

Locusts live in two contrasting phases:

Solitary Phase

Under normal conditions, these grasshoppers are innocuous, their numbers low and they pose no serious economic threat. They are shy, green or brown, live apart and move little.

Gregarious / Swarming Phase

Under specific triggers — drought followed by rapid vegetation regrowth — a neurochemical change (rising serotonin in their brains) switches their behaviour and physiology:

• They turn yellow-black in colour.
• They become sociable and nomadic.
• They breed rapidly, laying 60–80 eggs per female every few weeks.
• Dense populations encourage further gregarisation — a positive feedback loop.

The phases are part of the same species; the switch is environmental.

How Locusts Harm Agriculture

• Voracious eating — leaves, flowers, fruits, seeds, bark, growing points. Nothing green is safe.
• Weight damage — swarms descend with such density that they physically break plants.
• Exponential growth — each new breeding generation multiplies numbers many-fold.
• Wide crop range — cereals, pulses, vegetables, fruit trees, fodder. Virtually nothing is immune.
• Food security threat — particularly for subsistence farmers with no reserves or insurance.

A swarm of 1 km², moving through a wheat or mustard field, can eat the crop down to stubble in hours.

The Locust Cycle in South Asia

Desert locusts typically originate in the Arabian Peninsula and Horn of Africa. From there, they move via:

• The spring breeding grounds in Iran–Pakistan border.
• The summer breeding grounds in Indo-Pakistan desert (Rajasthan–Cholistan).
• The winter breeding grounds in Red Sea and Horn of Africa coasts.

India is at highest risk just before the monsoon onset (April–July), when mature swarms arrive from Pakistan's deserts, driven by westerly winds, and may stay if vegetation and rains permit local breeding.

The 2019–20 Upsurge

The 2019–20 upsurge was fuelled by an unusual sequence of:

• Cyclones in the Indian Ocean (2018 Mekunu, Luban) that brought rare heavy rains to Arabian deserts.
• Uncommonly wet conditions across the Horn of Africa and Arabian Peninsula in 2019.
• Instability in Yemen and Somalia hampering FAO-coordinated ground control.
• COVID-19 lockdowns in 2020 further slowing transnational response.

Swarms entered India from Pakistan in May–June 2020 and reached as far east as Maharashtra, Madhya Pradesh and Uttar Pradesh — far beyond the traditional Scheduled Desert Areas.

India's Locust Control Framework

Locust Warning Organisation (LWO)

• A specialised wing under the Department of Agriculture and Farmers Welfare, Ministry of Agriculture.
• Headquartered at Jodhpur, Rajasthan.
• Reports to the Directorate of Plant Protection, Quarantine and Storage (DPPQS), Faridabad.
• Mandate: monitoring and control of locust situation in Scheduled Desert Areas, mainly in Rajasthan and Gujarat, and partly in Punjab and Haryana.
• Field operations through Locust Circle Offices and Field Stations.

Coordination Mechanisms

• FAO Desert Locust Information Service (DLIS) — global monitoring; India is a reporting country.
• South-West Asia Commission for Desert Locust Control — joint mechanism with Pakistan, Iran, Afghanistan (the latter has been intermittent).
• Trilateral meetings (India–Pakistan–Iran) for the spring and summer breeding grounds.

Control Techniques

• Aerial spraying of organophosphates (malathion) from fixed-wing aircraft and drones.
• Vehicle-mounted spraying.
• Biological control using Metarhizium acridum fungus (Green Muscle).
• Ground surveys and satellite-aided hotspot mapping.

Challenges in Locust Control

• Political instability in breeding grounds — Yemen, Somalia, Afghanistan — limits FAO's aerial control.
• India–Pakistan tensions occasionally complicate border-area coordination.
• Climate change — warmer, wetter deserts can support year-round breeding.
• Resistance risk — over-reliance on a few pesticides.
• Farmer-level awareness — delayed reporting reduces effectiveness of spray windows.
• Drone regulations — only recently liberalised for agricultural use.
• Funding volatility at FAO and regional commissions.

Way Forward

• Pre-emptive surveillance using satellite remote sensing (soil moisture, vegetation indices) to identify breeding hotspots before swarms form.
• Drone-based spraying — India has expanded drone use since 2021.
• Regional cooperation — strengthen South-West Asia Commission with sustained funding and joint operations.
• Biological control scale-up — Metarhizium is environmentally safer than chemicals.
• Integrated Pest Management (IPM) awareness at village level.
• Climate-risk integration — treat locust upsurges as a climate hazard in disaster planning.
• Crop insurance coverage for locust damage — PM Fasal Bima Yojana now includes locust as a notified peril.
• Early warning communication in regional languages via SMS, radio, community networks.

Latest Developments (2024–26)

Updated context:

• Post-2020 upsurge controlled by mid-2021; no major swarm invasion of Indian territory since.
• FAO DLIS bulletins (2024–25) have kept the situation at "Caution" or "Threat" level, with breeding hotspots monitored in Ethiopia, Sudan, Yemen and Iran.
• 2023 cyclones in Arabian region briefly raised concern but swarms did not reach India.
• Drone spraying protocols standardised under DPPQS in 2023 — India is among the first countries to operationalise drones for locust control.
• Kisan Drone Yojana (2023–24) supports drone adoption including for pest control.
• Climate projections (2024) suggest increased frequency of "extreme wet" years in Arabian deserts under warming, which could raise future upsurge risk.
• India and Pakistan continue technical-level exchange on locust monitoring despite broader tensions.
• Bharatiya Krishi Anusandhan Parishad (ICAR-NCIPM) research on pheromone-based traps and microbial controls continued.

UPSC Relevance

Paper mapping: GS Paper III — Agriculture, Disaster Management, Environment.

Prelims pointers:

• Desert locust scientific name: Schistocerca gregaria.
• Family: Acrididae (short-horned grasshoppers).
• The chemical trigger for gregarisation is increased serotonin in locust brains.
• LWO is headquartered at Jodhpur, Rajasthan.
• LWO operates under DPPQS, Faridabad, Ministry of Agriculture.
• The main chemical used is malathion; biocontrol uses Metarhizium acridum.
• South-West Asia Commission for Desert Locust Control covers India, Pakistan, Iran, Afghanistan.
• A 1 sq km swarm contains 40–80 million locusts.
• 2019–20 upsurge was the worst in 27 years.
• The Scheduled Desert Areas primarily span Rajasthan and Gujarat.

Mains angles:

• "Discuss the role of climate change in the 2019–20 desert locust upsurge and examine India's preparedness for future outbreaks."
• "Evaluate the institutional and regional mechanisms for locust control, with suggestions for improvement."