What Are Pests | Introduction And Classification | Animal And Plant Pests

PESTS

Definition:

 pests are any living organism that can cause damage to crops, plants, timber, or clothes.

Explanation

It has been estimated that about one-third of the food crops of the world is destroyed by these various pests at various stages i.e. growth, harvest, and storage.

The rates of destruction often are higher in less developed nations.
The Food and Agriculture Organization (FAO) estimates that one-half of cotton production in developing countries would be lost to pests without the use of pesticides.
Several studies have shown that a country could not survive as a nation without pesticides.
Even in the US, crop devastation due to pests is estimated to be about 30% ($20 billion annually) even though pesticides are used widely here.
Several studies have shown that this country could not survive as a nation without pesticides.
Pests create the problem for the crops or foods etc. And the chemicals which are used to kill the pests are called Pesticides.
Pesticides are poisonous chemicals which are used to kill or get rid of the pests.
As pesticides are poisonous therefore they should be used under the supervision of a qualified person e.g. Pharmacist who has the knowledge about certain things:

• Method of application
• Signs & symptoms of poisoning
• Emergency treatment if the poisoning has occurred.

Pesticides are formed under certain rules and regulations.
Their synthesis is controlled by Federal Environmental Pesticides Control Act (FEPCA). According to this act, the producer will have to provide the scientific evidences not only about the efficacy but also the safety of the drug toward:

• Human beings
• Livestock, wild life and crops and
• General environment

All the above information are strongly recommended by the Federal Food, Drug and Cosmetics Act (FDCA).

Classification of Pests:

1. Animal Pests
2. Plant Pests
3. Fungi
4. Weeds
5. Rodents

ANIMAL PESTS

A) RODENTS:

These are the mammals e.g. Rats, mice, monkeys & rabbits etc. They have sharp teeth.
Rodents attack the stores and ware-houses, crude drugs and crops.
They also cause contamination of crude drugs and crops e.g. hair from rats and mice are generally included in contamination. Their removal is sometime hard and they are unhygienic as well.
Rodents may also be responsible for causing certain diseases from which they are suffering e.g. rat has certain micro organisms in their mouth which cause certain diseases e.g. fever, rat leprosy (slowly progressing bacterial infection) and plague etc. are caused by certain species of rats.
Some mites and ticks when bite the rat, take the infection from them and transfer it to human beings e.g. Rocky mountain spotted fever if not properly treated, become epidemic.

B) ARTHROPODES:

This group includes insects, spiders, ticks, lice & mites. Ticks and mites are ecto-parasites on human beings. Among arthropods, insects are more problem creators. On the basis of morphology of their mouth parts, they can be divided into two groups:
BITING OR CHEWING INSECTS:
They eat the leaves and stem of plants in all stages of their life cycle e.g. larva, pupa and adult stage e.g. Tomato hornworms, Corn ear worms, Codling moths (insect like butterfly), Locust etc.
SUCKING INSECTS:
They have modified mouth parts and are capable to puncture the soft epidermal tissue, thus sucking juice from it. E.g. Aphids (plant lice), Chinch bugs, Squash bugs, Cabbage bugs etc.
However,house hold insects belong to both groups e.g. cockroaches, cloth moths, carpet beetles, termites etc. are chewing insects while fleas, lice, mites, ticks, spiders, bed bugs &mosquitoes belong to sucking insects.
Malaria, dengue fever, yellow fever, sleeping sickness and other infectious diseases are spread by mosquitoes when they expel some of the protozoan laden saliva during the penetration of the human epithelium.
The hairy spider bite can kill the birds and small mammals.
The black widow spider causes pain.

PLANT PESTS

A) WEEDS:

Any undesirable plant that grows in a crop or field is called weed.
Ticks Dust Mites Grain Mites Louse.
Weeds may be harmful or harm less e.g. Mustard in the Clove field, thistle plant in the vegetable garden.
Weeds should be removed because they utilize nutrients and water from the soil, thus causing suffocation to the plant.
Weeds grow in the conditions of much sunshine, sufficient moisture and well fertilized soil which are provided for cultivation of some plants and vegetables.
If weeds are allowed to grow, they will soon acquire possession of the garden and gradually destroy the more delicate, cultivated plants. Similarly, the quality of the field crops, especially grains, becomes poor due to presence of weeds.
They are also responsible for:

• Reduction in growth of cultivated plants.
• Alteration of quality of cultivated grain.

Weeds containing cyanophore glycosides in their seeds cause dermatitis during harvesting of the crop e.g. Toxicodendron eradicans.
Seeds of certain weeds are poisonous when swallowed e.g. Datura.
Spores of certain weeds are allergenic and may cause hay fever, rhinitis (irritation and inflammation of the mucous membrane inside the nose) e.g. ragweed pollens.

B) FUNGI:

Fungi may result in many types of rust diseases e.g. rose rust, black berry rust, wheat rust, holly hock rust etc.
Fungi are responsible for causing many diseases in plants. Before sowing, seeds should be treated with anti fungal drugs e.g. Thiuram (Tetramethyl thiuram disulphide), while small plants should also be sprayed with anti fungal agents.

C) MICRO ORGANISMS PESTS:

Certain micro organisms are also responsible for causing various plant diseases e.g. Viruses cause tobacco mosaic and Bean mosaic while bacteria causes carrot rot, fire blight of apple and wilt of cucumber & melon.
Phycomycetes & Ascomycetes also cause some plant diseases.

For all the pests as explained in this section various pesticides have been practiced which will be discussed in next article here.

classification of pesticides