What are Insects?: Characteristics, Insects and Man, Types, Pest Control
What are insects?
Insect class is the largest class of animal kingdom. These are animals of Arthropoda Phylum. Their bodies are segmented like those of Annelida, but with a definite number of segments and an outer skeleton of a tough, chitinous cuticle secreted by the epidermis.
Out of about 1.5 million known animal species, about 1 million are of insects only. Therefore, the class of insects is very large, diverse and at present the most successful animal group found on the earth. That's why the study of insects is done under a separate branch of zoology which is called Insectology or entomology.
Major Characteristics of Insect Class
- The body of insects is ideally small, light and segmented.
- Their body is divided into head, thorax and abdomen. Head is useful for receiving sensations and for taking food and chest for walking.
- The basic number of segments is 6 in head, 3 in thorax and 11 or less in abdomen.
- They have large compound eyes, antennae and main appendages on their head.
- Ideally there are 3 pairs of legs and 1 or 2 pairs of wings on the thoracic part. Among invertebrates, only insects have the ability to fly.
- In the abdominal part of insects, there are usually organs related to reproduction with which they reproduce.
- Salivary glands are found related to the mouth apparatus.
- Most of the insects have a dense network of airways for respiration. Due to these, the external air reaches the tissues directly, due to which the gaseous exchange takes place in them with more intense pain. That is why the blood of insects is colorless and this colorless blood is called blood lymph ie hemolymph.
- Their root coelom cavity is very small. When large blood sinuses meet, a large secondary body cavity called hemocele is formed, which works as an "open circulatory system".
- Excretion in insects takes place mainly through special type of tubules called Malpighi tubules which open into the intestines.
- Insects are monogamous.
- Only sexual reproduction takes place in them. In these the accessory sex organs are highly developed and impregnation takes place in the body of the female and there are infant stages in the life cycle in which metamorphosis and epidermis take place.
The reason for the success of insects
Their distinctive features present in insects give them unique success in nature. The reasons for his unique success are as follows-
- Due to the small and light body of insects, the difficulty of housing and food is less for them. This difficulty is completely eliminated by the ability to fly in the air.
- The development of the sensory perception, especially the sense of sight, and the increase in the rate of respiration with the help of air ducts are favorable for their active life.
- Adaptation to the diversity of nutrients available in nature, their food habits are also diverse. Most of the appendages of the head act as mouth appendages, adapted according to the nature of the food, for proper intake of food.
- Accessory genitals are highly developed. Due to this, their reproductive capacity increases manifold.
Insects and Humans
Insects have a close relationship with human life. While insects are the most successful animals in nature in number and diversity, on the other hand, humans are the highest animals in the development of intelligence.
Therefore, competition between these two types of animals is definitely possible in the Struggle for Existence, so from the point of view of human efficiency, insects have been of most importance. There is no human being whose body or lifestyle has not been affected by insects.
The importance of insects to humans is so great that the study of this subject has developed into a separate subdivision of entomology called economic entomology.
We can divide the insects related to human life into two categories-
(a) Harmful insects
(b) Beneficial insects
(a) Harmful Insects
There are some insects which harm humans. They do not cause direct personal harm to any human being, but there will be no one who has not seen weevils in grains, grasshoppers in vegetables, flies, mosquitoes in homes and grasshoppers in fields and gardens etc. This tells us about the enormous potential of insects to cause harm. Although only about 1.4% of their species are harmful to humans, but they cause us huge and varied types of losses.
We can divide these harmful insects into three major categories -
- Pests harmful to agriculture
- Pests harmful to humans and pets
- Insects that harm stored food and other useful items
1. Pests harmful to agriculture
Man produces grains, fruits, vegetables etc. from the land through agriculture for food, but there is no such crop from which insects do not get their food. Insects get their food from the roots, stems, leaves etc. of trees and plants. Under this, those insects come which attack the roots, stems, leaves, buds, flowers etc. of trees and destroy them.
Under this, we can divide insects into the following categories-
(A) Insects that gnaw plants - Some insects eat plants by chewing them like a cow and a goat, such as grasshopper, potato katvi or kajra pillu, red pumpkin beetle.
(B) Sap-sucking insects - Many types of insects suck the juice by piercing their proboscis mouth appendages in the plants, due to which the plants dry up and die, such as cotton flounder, pirilla, sugarcane lahi, rice filth, cabbage champa, black sundar, mango oil or Lassie.
(C) Insects that burrow into plants and make them hollow (Burrowing Insects) - There are some insects whose caterpillars penetrate into the parts of tree plants and make them hollow, such as cotton bollworm, reed bollworm, maize borer, gram bollworm, wheat hessian fly.
2. Insects harmful to humans and pets
These can be divided into the following four categories-
(A) Insect Pests - Many types of insects are companions of humans and pets, such as cockroaches, red and black ants, crickets etc. in our homes. Where they do not cause any special harm to humans, but their smell and their touch with the body is not good.
(B) Poisonous Insect - Some insects are poisonous which cause physical pain to humans and animals. The experience of wasp and bee stings is very bitter and the bites of ants, mosquitoes etc. cause itching and burning sensation.
(C) Parasitic Insect - Some insects make the body of humans and domestic animals their home and get food from them, they are called parasitic insects, they can be divided into two categories- external parasite, endoparasite.
3. Destructive pests of stored food and other useful items
Some insects not only harm our agriculture, domestic animals and our body, but they also attack our food, manure stores and other useful things. They destroy many of our organic things for food like food-stuffs, medicines, leather goods, clothes, paper and books, wooden material etc.
The following types of insects come under this-
- food-destroying insects (Food Pests)- They cause maximum damage to the grains in our food store. These insects are members of the order Coleoptera and Lepidoptera. Ladybug, weevil, whitefly and moth are prominent under this. They pierce the grains of grains like wheat, rice, gram, peas etc. and plant eggs in them. The larvae that emerge from the eggs make the grains hollow by eating inside.
- Cloth Moth – It attacks the clothes. If woolen clothes are not kept properly, it makes holes in it at many places. It also attacks medicines, tobacco etc. and destroys them by making holes in cigars, cigarettes etc.
(b) Beneficial Insects
Many insects are also beneficial for us. Without them our life would be incomplete and sad. We can divide insects into several categories according to the benefits they provide.
Producers of useful things - Some species of insects come under this, from which we get useful things like silk, honey, wax, lac, dyes, medicines etc. Silk moth, bee, lac insect are such insects from which we get benefit like silk moth gives us silk and bee gives us wax, honey and other useful things. Red color is made from an insect named Lahi, which is used in making alta, as well as it is also used in making some medicines. We get lac from the lac insect, which India exports every year.
- Pollination of flowers - In cereal plants like wheat, maize, paddy, sorghum etc. pollination is done by wind but in vegetables and flowers pollination is done through insects. Bee is very important among these insects. It sits atop hundreds of flowers every day to collect honey, which pollinates the flowers. Along with this, bumblebee also helps in pollination of many crop plants.
- Edible insects - Although insects are small, but due to their easy availability in large numbers, some birds and fish eat them. Humans then take advantage of these fish and birds by hunting them. Some humans themselves also eat insects. Some species of crickets and moths are especially important among these insects.
- Pests that destroy useless plants - Some pests destroy plants that are abundant in fields, gardens, forests and are harmful to crops.
- Glistening Insect - Some insects have light producing organs on their abdomen. By producing light at short intervals, male and female insects appeal to each other for copulation.
Pest Control
If the number of harmful insects increases according to the reproductive capacity, then it can destroy the human race in a few years. But due to environmental changes, due to animals, bacteria, etc., they are automatically destroyed in large numbers, this type of destruction can be called the control of nature.
Artificial Pest Control - Under this, we find many methods to control pests, out of which mechanical control, physical control, biological control, cultural control, scientific control and chemical control are the main ones. By this we can control insects artificially and prevent them from growing so that they do not harm crops, animals and humans etc.
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