Early Locusts

Why in news?

Last month, the Locust Warning Organisation (LWO) observed desert locusts in western part of India.

What is LWO?

• It is a part of the Union Agriculture Ministry’s directorate of plant protection, quarantine & storage.
• It has a field headquarters at Jodhpur in Rajasthan.

Why these locusts are a concern?

• These desert locusts are the destructive migratory pests currently devouring acres of crops in East Africa.
• While locusts are seen in India as well, that is normally only during July-October and mostly as solitary insects or in small isolated groups.
• This year, their being spotted along the India-Pakistan border before mid-April has raised the alarm bells.
• They have damaged the growing rabi crops along western Rajasthan and parts of northern Gujarat during December-January.

What exactly are locusts?

• The desert locust (Schistocerca gregaria) is a short-horned grasshopper.
• Solitary phase - In “solitary phase”, these winged insects are safe.
• They become dangerous only when their populations build up rapidly.
• Close contact in crowded conditions trigger behavioural changes.
• Gregarious phase - They enter the “gregarious phase”, by grouping themselves into bands and forming swarms.
• They travel great distances (up to 150 km daily), while eating up every bit of vegetation on the way.
• If not controlled at the right time, these insect swarms can threaten the food security of countries.

How the LWO’s first sighting of the locusts should be viewed?

• No worries, for now - The rabi crops has already been harvested and kharif crops are yet to be planted.
• The LWO has detected “gregarious” hopper groups, including in Punjab adjoining the Pakistan border.
• But no breeding or swarm movement has also been seen so far.
• Timing, a concern - Their normal breeding season in India is July-October. But this year, they have been sighted by mid-April.
• Last year, too, they were seen towards end-May as isolated grasshoppers.
• But, they could breed to high enough populations for forming swarming and wreaking havoc during the rabi season in Rajasthan and Gujarat.
• The longer time to breed is more conducive for build-up of gregarious insect swarms, as opposed to solitary hoppers.

What kind of damage can they cause?

• Locusts are polyphagous i.e., they can feed on a wide variety of crops.
• Locusts can multiply rapidly, a single female desert locust lays 60-80 eggs thrice during its roughly 90-day life cycle.
• The damage potential of locusts has been limited in India, as India hosts only one breeding season.
• [In Pakistan, Iran and East Africa, they also multiply during January-June.]

What is the genesis of the present locust upsurge?

• It lies in the Mekunu and Luban cyclonic storms of May and October 2018 that struck Oman and Yemen, respectively.
• These turned large desert areas in remote parts of the southern Arabian Peninsula into lakes.
• This allowed the insects to breed undetected across multiple generations.
• The swarms attacking crops in East Africa reached peak populations from November onwards.
• They build up since the start of this year in southern Iran and Pakistan.
• Widespread rains in East Africa in late March and April have enabled further breeding.

What is the prediction?

• A part of the new generation of swarms forming in late-June/July may migrate from the Horn of Africa across to the desert areas along India-Pakistan border.
• During May-Junet, the locusts from spring breeding areas of southwest Pakistan and southern Iran would arrive in Rajasthan and Gujarat.
• They would, then, breed with the onset of the southwest monsoon rains and continue doing so through the kharif cropping season.

What should be done?

• If the monsoon is good, and in the absence of control operations, the magnitude of attack could be worse than in the 2019-20 rabi season.
• In 2019-20, Rajasthan and Gujarat had to treat over 4.30 lakh hectares of infested areas with sprayers mounted on tractors and other vehicles.
• Old generation organophosphate insecticides such as Malathion (96% ultra-low volume aerial application) are effective against locusts.
• About one litre of the chemical is necessary to treat a hectare of their breeding areas, including trees where they halt for the night.
• There is ample stock of pesticides to control any swarms.
• Control operations require procurement of equipment, training of field teams, prepositioning of supplies in key breeding areas and updating contingency plans.

Source: The Indian Express