What Exactly are Insecticides?

Insecticides are substances designed to exterminate insects and are extensively used in agriculture, medicine, and industry. They can significantly impact ecosystem components and are potentially harmful to both humans and animals. Some insecticides can even accumulate as they move up the food chain.

Table of Contents

• Classification of Insecticides
• Types of Insecticides
• Insecticides Categorized by Chemical Composition
• Drawbacks of Using Insecticides

Classification of Insecticides

• Classified by chemical composition: organic and inorganic.
• Classified by entry method in insects: contact poisons, fumigants poisons, stomach poisons, and systemic poisons.
• Classified by action mode: physical poisons, nerve poisons, respiratory poisons, protoplasmic poisons, general poisons, and chitin inhibitors.
• Classified by toxicity level:
  1. Extremely toxic – Red color, skull and poison symbol, oral LD50: 1-50
  2. Moderately toxic – Blue color, danger symbol, oral LD50: 501 – 5000
  3. Highly toxic – Yellow color, poison symbol, oral LD50: 51 – 500
  4. Less toxic – Green color, caution symbol, oral LD50: >5000
• Classified by stage specificity: ovicides, pupicides, larvicides, and adulticides.

Types of Insecticides

There are three main types of insecticides:

• Systemic – These insecticides are applied to the soil for absorption by plant roots. They then travel to the plant's outer regions like leaves, fruits, and branches, poisoning any insect that tries to feast on the plant.
• Ingested – Examples of this type include rat and cockroach baits.
• Contact – These insecticides work like bullets, targeting specific insects. Household insect sprays are a good example of contact insecticides.

Insecticides Categorized by Chemical Composition

Insecticides can be grouped into four categories based on their chemical nature:

• Organic insecticides
• Synthetic insecticides
• Inorganic insecticides
• Miscellaneous compounds

Drawbacks of Using Insecticides

• Negative Impact on Non-target Organisms – Insecticides can cause harm to more than just the intended insects and can be harmful to humans. They can also contaminate water sources, affecting aquatic wildlife. For instance, birds consuming contaminated water or affected insects can die. Certain insecticides, such as DDT , have been prohibited in certain countries due to their negative impact on bird reproduction.
• Resistance Development – Insects can develop resistance to insecticides over time, reducing their effectiveness. Insects reproduce quickly, leading to a new generation every few weeks, so resistance can build up rapidly.

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