Effects of pesticides on pollution

A pesticide is any substance or mixture of substances intended for preventing, destroying, repelling, or mitigating any pest. It is also any substance or mixture of substances intended for use as a plant regulator, defoliant, or desiccant. Pests are living organisms that occur where they are not wanted or that causes damage to crops or humans or other animals. The pests may be insects, nematodes, rodents, weeds, fungus etc. The use of pesticides is associated with agriculture and horticulture.

Types of pesticides

Pesticides may be natural or synthetic. The pesticides are categorized as follows;

Organochlorine Pesticides

They are the synthetic organic pesticides that are earliest discovered and used. Their characteristics are broad-spectrum, long residual effect and relatively low toxicity. However, due to their stable chemical nature, they are hard to break down in the natural environment. Prolonged use in large quantities will easily lead to environmental pollution and accumulation in mammals, resulting in cumulative poisoning or damage. Organochlorine pesticides are therefore banned under general circumstances and gradually replaced by other pesticides.

Organophosphate Pesticides

Organophosphate pesticides are characterised by their multiple functions and the capacity of controlling a broad spectrum of pests. They are nerve poisons that can be used not only as stomach poison but also as contact poison and fumigant. These pesticides are also biodegradable, cause minimum environmental pollution and slow pest resistance. Temephos and Fenitrothion are examples of organophosphate pesticides.

Carbamates

Carbamate pesticides work on the same principle as organophosphate pesticides by affecting the transmission of nerve signals resulting in the death of the pest by poisoning. They can be used as stomach and contact poisons as well as a fumigant. Moreover, as their molecular structures are largely similar to that of natural organic substances, they can be degraded easily in a natural manner with minimum environmental pollution. Propoxur is an example of carbamate pesticides.

Pyrethroid Pesticides

Pyrethroid pesticides are a pesticide synthesized by imitating the structure of natural pyrethrins. They are comparatively more stable with longer residual effects than natural pyrethrins. Pyrethroid pesticides are highly toxic to insects but of only slight toxicity to mammals. Allethrin and Permethrin are examples of pyrethroid pesticides.

Effects of pesticides

• Although pesticides save about 10% of the world food supply from the pests but these causes serious environmental and health threats to various living organisms.
• The use of pesticides in the farms, gardens, houses may also kill the useful organisms such as natural enemies (predators, parasites, and pathogens) as well as earthworms.
• Pesticides might be the major cause of the decline of reproduction in some animals.
• It pollutes the environment because of its higher dose.
• These are threats to wildlife and human health.

Alternatives to pesticides

Biological control

The biological control of pest has traditionally meant regulation by natural enemies such as predators, parasites, and pathogens. It represents a form of population management preventing an unchecked exponential growth of pest species.

Cultural control

It is the method to control the plant pests by the rotation of crop.

Integrated pest Management (IPM)

IPM is a combination of common sense and scientific principles. It's a way of thinking about pest management that values:

• Using knowledge about the pest's habits, life cycle, needs and dislikes.
• Using the least toxic methods first, up to and including pesticides.
• Monitoring the pest's activity and adjusting methods over time.
• Tolerating harmless pests.
• Setting a threshold to decide when it's time to act