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Classification of Pesticides Based on Origin and Pest Control
Pesticide is a chemical or biological substance that is intended to prevent or repel or destroy the pests that may damage or disturb the growth or health of living organisms which may be plants or animals. These pests include insects, rodents, fungi, weeds, nematodes, algae, etc.

These pesticides are classified on the basis their origin or structure or pests they control or the mode/ site of action.

Classification based on their origin-
There are two types – chemical pesticides and bio pesticides.

Chemical pesticides are further divided into four types based on their origin -

Organophosphate pesticides - These are the chemical substances which are produced due to reaction between phosphoric acid and alcohols. This affects the nervous system by inhibiting the action of enzyme acetyl cholinesterase (AChE). This causes irreversible blockage leading to accumulation of the enzyme which results in overstimulation of muscles. These mainly include insecticides, nerve gases, herbicides, etc.

Carbamate - These are esters of carbamic acids. The mode of action is inhibiting acetyl cholinesterase similar to that of the organophosphates but the bond formed for inhibition is less durable and thus reversible. These also include mainly of insecticides.

Organ chlorine pesticides- These are the derived from chlorinated hydrocarbons. These are endocrine disrupting agents which effect on the hormonal systems of the body, act as duplicates of the normal hormones and thus causing adverse health problems. They remain in environment for a long time by breaking down slowly and accumulating in the fat tissues of animals. A well-known example is DDT (dichloro diphenyl trichloroethane).

Pyrethroid pesticides- These are potent nuero poisons, endocrine disruptors and cause paralysis. Pyrethroids are synthetic version of pyrethrin a natural insecticide. They have similar chemical structure and similar mode of action as of pyrethrin which is obtained from chrysanthemum. These are derivatives of ketoalcoholic esters of chrysanthemic and pyrethroic acids and are more stable in sunlight than pyrethrins. These are most popular insecticides as they can easily pass through the exoskeleton of the insect. Few examples are- deltamethrin, cypermethrin, etc.

These are naturally occurring materials or derived naturally from living organisms or their metabolites, like bacteria, fungi, plants, etc. These are classified into three major groups-

Microbial pesticides- This has microorganisms acting as pest controllers like bacteria, fungi or viruses. Each of it contains specific target. Widely used are strains of Bacillus Thuringenesis or Bt and its subspecies. The mode of action generally is producing a protein that binds to the larval gut receptor which starves the larvae.

Biochemical pesticides- They are naturally occurring, nontoxic pest controllers. These include pheromones, natural plant and insect regulators, enzymes, bio repellents or attractants.

Plant incorporated protectants (PIPs) - These substances are produced by plants naturally but the gene necessary for production of pesticide is introduced into the plant through genetic engineering. The substance produced by the plant and the genetic material introduced are together defined as plant incorporated protectants (PIPs).

Classification based on their pests they control-

Insecticides- These act especially on insects.
Algaecides- control or kill growth of algae.
Herbicides – controls or kills weeds.
Bactericides - acts against bacteria.
Fungicides- acts against fungi.
Rodenticides- kills or prevents rodents i.e. rats or mice.
Larvicides – inhibits growth of larvae.
Repellents – they tend to repel pests by its taste or smell.
Desiccants- they act on plants by drying their tissues.
Ovicides – they inhibits the growth of eggs of insects and mites.
Virucides- acts against viruses.
Molluscicides – they inhibit or kill mollusc’s i. e snail’s usually disturbing growth of plants or crops.
Acaricides – they kill arachnids like mites.
Nematicides – they are tend to kill nematodes that act as parasites of plants.
Avicides – these are used to kill birds.
Moth balls- these are used to stop any damage to cloths by moth larvae or molds.
Lampricides – these are designed to target larvae of lampreys which are jawless fish like vertebrates in the river.
Piscicides – they are substances that act against fishes.

Though pesticides are designed to kill or inhibit organisms that cause damage to the crops or animals, they have harmful effects on other organisms that must not be effected and tend to pollute the environment. If used in high quantities they can be lethal sometimes. Biopesticides are used instead of chemical pesticides as the negative effects are low compared to chemical pesticides.
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The Best way of getting rid off Pest is call the pest control exterminator.
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Very nice information. I think I have read the best answers for pesticide. Pesticides can help us how to solve problems like rats. This can more useful to everyone.
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Biological pesticides are a modern approach of controlling pests without causing much harm to the environment. Biological pesticides are certain groups of pesticides that are derived from bacteria, plants, animals, and certain minerals. There are three major categories of biopesticides. These are Microbial pesticides wherein the active ingredient is a microorganism for example a bacterium, fungus or protozoan. Some specific examples include fungi controlling specific weeds or killing insects. Bacillus thuringiensis and its subspecies is most commonly applied biological or microbial pesticide of all. It is abbreviated as Bt. Pesticide materials that can be produced by plants through the genetic material incorporated in them are collectively known as Plant-Incorporated-Protectants or (PIPs). For instance, scientist used the toxic gene from Bt to slot inside the plant genome so that the plant can produce the toxin by itself, thereby destroying the pests. EPA in these circumstances regulates the genetic material and the protein, thus generated and not the plant itself. The third class is Biochemical pesticides which include natural materials that have non-toxic mechanisms to control pests. Examples of Biochemical pesticides are insect sex pheromones (act by interfering in mating), a range of aromatic plant extracts (work by attracting insect pests into traps).
The host specificity is the chief advantages of using biological pesticides. Biological pesticides only act on the target pest and strongly linked organisms, whereas chemical pesticides are usually of broad spectrum types which affect a large group of organisms which may not fall into pest category (mammals, insects, birds). Biopesticides are usually environmentally friendly as they are less toxic, decomposed easily and required in small quantities. Chemical pesticides cause major environmental pollution as they are quite toxic and not always biodegradable. Another important advantage of using biological pesticides is the fact that they are less susceptible to genetic modification in plant populations. This ensures that there is far less chance of growing pesticide resistance in pests, a problem highly associated with the use of chemical pesticides. Pesticide resistance is a major concern in fields receiving chemical pesticides and use of biological pesticides can easily solve the problem. But appropriate pest management through biological pesticides depends on the application technique. Special spraying techniques are there for evenly distributed application of bio-pesticides in sufficient quantity (droplets containing the required number of organisms) on the target species to offer enough impact on the target pest. The application procedure, thus forms the integral part of the successful bio-pesticides treatment.
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