Get the answer of: Why the Study of Arthropods is Necessary?
Academic Interest:
Arthropods are many and they inhabit all sorts of environment. The study of these animals, therefore, can help the student to understand—What are the requirements of each kind of environment and how can a living organism develop structural features to adjust with each way of life?
The long history of these animals on the earth, specially the study of forms like Peripatus and Limulus provide an excellent opportunity to understand the process of evolution. Variation which is considered as the essential theme of life, may be well studied from insects, specially butterflies, moths and beetles.
Our understanding of ecological niches, interdependence of living organisms and biological rhythm have largely come from the study of Arthropods.
Recent developments of genetics and embryology are largely based on the work done on Arthropods like Drosophila and Chironomous larvae. To summarise, it may be said that the study of Arthropoda is essential to understand taxonomy, evolution, embryology, ecology and genetics.
Applied Interest:
No other phylum is so much associated with the human life as the Arthropods. Numerous members of the group are considered injurious and many are beneficial to man to such an extent that it is assumed that if all the Arthropods are eliminated from the earth the human population will also be destroyed.
Injurious Arthropods:
The injurious Arthropods fall in two categories:
(a) Which destroy crop plants, damage stored foods and other goods,
(b) Which affects man and his domestic animals causing injury either directly or by transmitting germs of various diseases.
(a) Arthropods which damage crop plants and stored articles.
A large number of Myriapods, Insects and Arachnids eat on plant parts on which man is interested. These are commonly called pests.
The well-known pests of paddy are Spodoptera mauritia, Heliothis armigera, Agrotis ypsilon, Cirphis albistigma, Psalis securis, Nymphula depunctalis, Melanitis ismene, Schoenobius incertulus (all belonging to the Lepidoptera), Hispa armigera (Coleoptera), Leptocorisa acuta, Ripersia oryzae (both Hemiptera) and a few others from Diptera, Thysanoptera and Orthoptera.
A large number of pests are also known in wheat (Sesamia inferens, Agrotis ypsilon, Toxoptera graminum), in Sugarcane (several members of the group Lepidoptera, e.g., Argyria sticticraspis, Diatroea venasota, different Isoptera, e.g., Odontotermes obesus and the Hemipteran insect, Pyrilla perpusilla), in tea plants (Helopeltes theiovora of Hemiptera), in jute plants (two members of Lepidoptera, Anomis sabulifora and Dicrasia obliqua and a Coleopteran insect Apion corchoris) and in cotton (several Lepidoptera like Earias fabia, Platydera gossypiella, Sylepta derogata, two Coleopteran insects, Pempheres affinis and Sphenaptera gossypii and one Hemiptera, Dysdercus cingulatus).
The stored food grains are commonly affected by insects like Calandra oryzae, Tribolium castaneum, Rhizopertha dominica and Ephestia kuhniella. Several other insects like cockroaches, ants, beetles, several kinds of moths and termites damage stored food and different articles like clothes, books and furniture.
(b) Arthropods which damage the health of man and his domestic animals:
The arthropods may affect the health of man either by direct attack or by transmitting germs of various diseases.
Such arthropods may be grouped into following categories:
(i) Permanent ectoparasites:
Arthropods which spend entire or major part of their life cycle on the external surface of the host, e.g., Pediculus humanus (Anoplura, Insecta), Pulex irritans (Siphonaptera, Insecta), Demodex folliculorum (Acarida, Arachnida).
(ii) Obligatory endoparasites:
Some arthropods pass only certain stages of its life cycle as endoparasites, e.g., larval stages of insects belonging to the family Gastrophilidae and Oestridae (both Diptera).
(iii) Temporary ectoparasites:
These arthropods attack man and domestic animals for food but live a free-living life, e.g., Mosquito and other Dipteran insects; Cimex, Triatoma and Rhodinus (all Hemiptera) and the Arachnids belonging to the family Ixodidae (Acarida).
(iv) Poisonous forms:
Several Arthropods possess various structures for offence and defence. Such structures often cause considerable damage to man, e.g., Poison spine of spider (Arachnida). Sting of Honeybee, Wasps (Insecta), Hairs of Caterpillar (Lepidoptera, Insecta).
(v) Transmitter of Diseases:
The transmission of diseases is caused either mechanically by different Arthropods or biologically by permanent and temporary ectoparasites. The best examples of mechanical transmission are house-fly, cockroaches, spiders which contaminate foods or drinks by various germs, Typhoid, Cholera, etc. which are carried on the legs and other body parts.
The diseases like Malaria, Sleeping sickness, Chagas disease and Bubonic plague are the results of biological transmission of germs by different insects.
Beneficial Arthropods:
Arthropods which are beneficial have great commercial value. They serve as food, clothing’s and apparels, utilitive articles, pollinating agents and also agents for controlling injurious arthropods. The crustaceans like prawn, lobster, crab and shrimps are regarded as delicious foods. A large number of Crustaceans which live as plankton serve as the food of fishes which in turn are the foods of man.
Numerous birds and also several mammals are insect eaters. Man gets honey from honey-bee, silk from silk worm and lac from lac insects.
Honeybees, Butterflies, Moths and several other insects are well known pollinating agents and help in increased production of crops and other plant products. Numerous Insects, Arachnids, Diplopods are insect-eaters and they serve us by destroying many injurious Insects and Arachnids.
From our knowledge of arthropods we have learnt the handling of injurious and beneficial insects. Numerous chemicals like BHC (Benzene hexachloride), DDT (Dichloro Diphenyl Trichloroethane), TEPP (Tetraethyl Pyrophosphate), Arsenic compounds and Carbon disulphide are in our hands to control the injurious forms.
Several improved techniques are now known to increase both the quality and quantity of Arthropod pro-ducts like honey, shellac and silk. It has been realised that instead of indiscriminate use of insecticides it is necessary to rely more on biological controls. A number of problems are still unsolved and require further investigation.