Classification of insecticides

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Classification of Insecticides

• Based on mode of action

Nikita saini B.Sc medical (III yr) 202225
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Physical poisons
Protoplasmic poisons
Insecticide
Respiratory poisons
Nerve poisons
Insect growth regulators
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PHYSICAL POISONS

• Toxicants which bring about kill of insect by
  exerting a physical effect.
• Asphyxiants (cause unconsciousness or death by
  suffocation) e.g. Heavy mineral oils.
• Abrasives (loss of body moisture/dessication)
  e.g. Inert dust, aluminum oxide.
• Absorbing moistures e.g. Charcoal, activated
  clay.

Fig Activated clay
Fig Inert dust
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PROTOPLASMIC POISONS

• Toxicants responsible for precipitation of
  protein especially destruction of cellular
  protoplasm and midgut epithelium.
• e.g. Heavy metals like mercury, copper,
  formaldehyde, fluorine and arsenic compound.

Fig Insecticide containing arsenic compounds
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RESPIRATORY POISONS

• Chemicals which block cellular respiration.
• They combine with enzymes like cytohrome oxidase
  and other oxidases containing iron and inhibit
  their catalytic action.
• E.G. Hydrogen cyanide, carbon monoxide, etc.

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NERVE POISONS

• These chemicals inactivate acetylcholinesterase.
  So formation of acetylcholine is blocked and
  nerve impulse conduction is disrupted.
• e.g. Organochlorines, Organophosphates,
  carbamates.

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INSECT GROWTH REGULATORS

• An insect growth regulator (IGR) is a chemical
  substance that inhibits the life cycle of an
  insect.
• IGRs are typically used as insecticides to
  control populations of harmful insect pests such
  as cockroaches and fleas.
• Hormonal IGRs typically work by mimicking or
  inhibiting the juvenile hormone (JH), one of the
  two major hormones  involved in insect molting.
• Chitin synthesis inhibitors interfere with
  process of synthesis of chitin due to which
  molting and development is disrupted.

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Hydroprene(Gentrol), Methoprene(Precron),
Triflumuron(Starycide)
Examples-
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Some larvae may stay in this juvenile stage until
they die.
Adults reproductive organs are affected and the
adult becomes sterile.
Eggs treated with IGRs may never hatch. If the
eggs do hatch, the young insect may not survive.
Treatment with an IGR may prevent the pupa from
becoming an adult and reproducing.
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Thank you