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Monocrotophos 36% SL (Phaskil)

Monocrotophos is a highly toxic organophosphate insecticide marketed in India in 36% SL formulation under brands such as Phaskil. Long used for broad-spectrum sucking and chewing pest control, it has been under regulatory restriction for several years and is being phased out under the Insecticides (Prohibition) Order 2023.

Composition / Active ingredient

  • Active ingredient: Monocrotophos
  • Formulation: 36% SL (soluble liquid)
  • Chemical class: Organophosphate (Class I, highly hazardous per WHO)

Mode of action

Monocrotophos is an acetylcholinesterase (AChE) inhibitor, classified under IRAC Group 1B. It binds and phosphorylates the active serine residue of AChE, preventing breakdown of acetylcholine at synapses. The result is continuous nerve over-stimulation, leading to tremors, paralysis and death. Both insect and mammalian AChE are inhibited; the mammalian toxicity is the basis of its Class-I classification.

Target use and dose

Historically used across cotton, paddy, sugarcane, soybean and pulses for aphids, jassids, whitefly, thrips, mites, bollworms and stem borer. In chilli sucking-pest tank-mixes, monocrotophos 36% SL (Phaskil) is applied at 500 ml/acre with Rogor (dimethoate 30% EC) 400 ml/acre in 150-200 L water against thrips, mites, aphids and jassids.

Safety and regulatory status

Monocrotophos is one of the most-debated pesticides in India. It was:

  • Reviewed under the Anupam Verma Committee (2015) on 66 pesticides;
  • Banned on all vegetables by India for residue and toxicity concerns;
  • Notified for phase-out under the Insecticides (Prohibition) Order 2023 (S.O. 4294(E), dated 3 October 2023), with a one-year transitional period and no new certificates of registration for its manufacture.

Modern substitutes include neonicotinoids (Acetamiprid, Thiamethoxam Actara), diafenthiuron (Diafenthiuron Pegasus) and diamides for caterpillars (Chlorantraniliprole).

See also: Acephate, Chlorpyrifos Cypermethrin, Acetamiprid, Thiamethoxam Actara, Fipronil.

References

  1. Banning of Pesticides. Press Information Bureau, Government of India.
  2. India Bans Four Pesticides Including Monocrotophos. ChemLinked.