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PEST: A pest is any living organism, whether animal, plant or fungus, which is invasive or troublesome to plants or animals, human or human concerns, livestock, or human structures.
PESTICIDES: A pesticide is any substance or mixture of substances intended for preventing, destroying, repelling, or mitigating any pest.
PESTICIDES POLLUTION: Pesticide pollution is defined as any substance or mixture of substances in the food of either humans or animals caused by the use of pesticides and any specified derivatives, such as degradation and conversion products, metabolites, and impurities and are considered toxic.
Types of Pesticides:
Based on Composition:
- Organochlorides: They are the Pesticides which contain organic chlorides. Some examples are: DDT, BHC, Aldrin, Dieldrin, Chlordane, Toxaphene, etc.
- Organophosphates: Pesticides which contain phosphates like parathion, malathion, diazion, phenothate guthion, etc.
- Carbamates: They contain carbamic acid aggregates. Eg: pyrethrins, baygons, temik, zectran, etc.
- Pyrethroids: Pesticides of plant origin. Got this name due Pyrethrin from flower Chrysanthemum. Others are obtained from neem Plant, Artemisia leaf, etc.
Based on Pest:
- Insecticides & rodenticides: Zinc Phosphide, Arsenic compounds
- Nematicides: Aliphatic Halogen compounds, organophosphate
- Herbicides: Phenoxy acids, Paraquat, Diquat & Triazoles.
- Fungicides: HCN, Ethylene oxide, acetaldehyde & methyl bromide
Modes Of Action:
- Insecticides are either Nervous or respiratory poisons
- Organochlorides are nervous poisons. They enter inside insects body either through integument (cuticle) or Spiracles.
- Once entered into the body, they reach nerve fibres and inhibit Na+, K+ and Mg++ ATPase activity in the synapsis.
- The poisons mostly affect the sensory or motor nerve fibers as well as motor cortex, thus results nerve paralysis & ultimately insect pests die.
- The respiratory poisons enter through spiracles & cause nausea, vomiting and nervousness leading to death due to respiratory arrest.
- Herbicides attack the photolysis of water ( Photosynthesis II) and evolution of O2 in the process, Harms growth and also affects the translocation of organic solutes.
DDT( Dichloro Diphenyl Trichloro-ethane) however banned, is relatively cheap to produce and still considered a good for certain tasks( Malaria control). It’s a broad-spectrum pesticide. As it is highly poisonous and non-degradable, it persists in the environment for a long time. It passes in various organisms through the food chain. It gets deposited in the tissues of animals and affects human health directly and indirectly and causes cancer.