Introduction
Natural pesticides are substances obtained from plants, animals or minerals that help control pests in a safe and eco-friendly way. These pesticides are preferred in organic farming because they degrade quickly, show low toxicity to humans and do not leave harmful residues. Many medicinal plants produce natural chemicals to protect themselves from insects, fungi and microbes. These chemicals can be used as natural pest-control agents.
Advantages of Natural Pesticides
- Biodegradable and environmentally safe.
- Less toxic to humans and animals compared to synthetic pesticides.
- Pests develop resistance more slowly.
- Suitable for organic agriculture.
- Reduce chemical load in soil and water.
Sources of Natural Pesticides
Natural pesticides mainly come from plants (botanical pesticides), microbes (microbial pesticides) and certain minerals. Among these, botanical pesticides are the most widely used in traditional and modern agriculture.
Important Natural Pesticides
1. Neem (Azadirachta indica)
Neem is one of the most important natural pesticides. The main active compound is azadirachtin.
Actions
- Acts as an insect repellent.
- Disrupts insect growth and reproduction.
- Reduces feeding activity.
- Affects more than 200 pest species.
Uses
Used in agriculture, stored grains protection and mosquito control.
2. Pyrethrum
Pyrethrum is obtained from flowers of Chrysanthemum cinerariifolium. The active chemicals are pyrethrins.
Actions
- Fast-acting contact insecticide.
- Targets insect nervous system.
- Low toxicity to humans.
Uses
Used in sprays, mosquito coils and household insect killers.
3. Nicotine
Nicotine is obtained from leaves of tobacco (Nicotiana tabacum).
Actions
- Powerful insect neurotoxin.
- Acts quickly and is very effective against chewing insects.
Limitations
- Toxic to humans in high amounts.
- Not commonly used today due to safety concerns.
4. Rotenone
Obtained from roots of plants like Derris and Lonchocarpus. It has long been used as a natural insecticide.
Actions
- Interferes with insect respiration.
- Effective against leaf-eating insects and some aquatic pests.
5. Essential Oils
Many essential oils also have insecticidal properties. These include eucalyptus oil, peppermint oil, clove oil and citronella oil.
Actions
- Insect repellent.
- Antifungal and antibacterial activity.
- Used in aromatherapy-based pest control.
6. Mineral-Based Natural Pesticides
Some minerals act as natural pesticides.
- Sulfur: Used to control fungal infections.
- Lime-sulfur: Controls mites and fungi.
- Diatomaceous earth: Kills insects by damaging their outer layer.
Microbial Pesticides
These pesticides contain microorganisms such as bacteria, fungi or viruses that target specific pests.
Examples
- Bacillus thuringiensis (Bt): Produces toxins lethal to caterpillars and mosquitoes.
- Beauveria bassiana: Fungal pesticide used against insects.
- Nuclear polyhedrosis viruses (NPV): Target specific insect larvae.
Modes of Action of Natural Pesticides
- Repellents that keep insects away.
- Antifeedants that stop insects from feeding.
- Growth regulators that block insect development.
- Nerve poisons that disrupt the nervous system.
- Physical actions like drying or suffocation.
Limitations of Natural Pesticides
- Short duration of action due to fast degradation.
- Often need repeated application.
- Some may be less effective than synthetic chemicals.
Applications
- Used in organic farming and herbal cultivation.
- Applied on vegetables, fruits and stored grains.
- Used in household insect control products.
Detailed Notes:
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