Arthropoda is the phylum
of animals that include the insects, arachnids, crustaceans and others that are
characterized by the presence of jointed limbs. Arthropodology
(from Greek; arthron = joint, podos = foot & logous =
to study) is a biological discipline concerned with the study of arthropods.
Entomology (from
Greek; entomos, "cut in pieces or engraved/segmented", hence
"insect"; and & logous = to study) is the Scientific
study of Insects and a branch of arthropodology.
Entomologists
are the scientists who study, collect, rear and experiments on insects. The
insects are easy to work upon for a number of reasons, easy to culture in lab,
short life cycles, rapid population turnover and lesser ethical concerns to
experiment on insects compared to other vertebrate insects.
 |
| Honeybee on a Sunflower |
Biodiversity of Insects
Over 1 million
species have been described and work has been published, but the estimated
number is much higher as well as many species have been extinct. Entomologists
estimate that estimated number of insects is between 3-80 million species. And
among the described species 40% are beetles (order Coleoptera) which are more
than 3,50,000 described species and next are bees (order Hymenoptera) which
have more than 2,50,000 described species. More will be discussed in a separate
article about biodiversity of insects.
Importance of Insects
Insects are
key players in our ecosystem as a whole and they cannot be simply sidelined or
eradicated from our planet. Their utmost significance is being summarized as
follows;
1. Pollination and Seed Dispersal
Perhaps the
most economically important function of insects comes in the form of
pollination while collecting nectar from the flowers. If there are no honeybees
for pollination of our agricultural crops, the estimated cost of artificial
pollination is nearly 100 US dollars globally in 2003.
2. Nutrient recycling
Nutrient recycling is also a very
eco-friendly activity of the insect world. The activities of insect such leaf-litter
and wood degradation, dispersal of fungi, disposal of carrion and dung and soil
turnover help to restore nutrients in the environment.
3. Honey production
Honey produced
by the honeybees is perhaps one of the most important gift of nature because of
many useful health benefits to humans.
4. Silk
Silk from the cocoons of silkworm
moths, Bombyx mori, and related species has been used for fabric for centuries,
and two endemic South African species may be increasing in local value.
5. Shellac
The lac insect Kerria lacca,
is a source of a commercial varnish called shellac.
6. Chitin and its Derivatives
Chitin, a component of insect
cuticle, and its derivatives act as anticoagulants, enhance wound and burn healing,
reduce serum cholesterol and many other applications are being sought.
7. Source of food
Insects are
either used as food or provide material to be used as food such as honey. Insects
are also present at the lower levels of food webs, serving as food for other insectivorous
animals like mammals, reptiles, amphibians and fish.
8. Model Organisms for Biological Research
Characteristics
of certain insects make them useful organisms for conducting biological research.
For example, high fecundity, short life span and ease of rearing and
manipulation in lab, vinegar fly, Drosophila melanogaster has been model
organism for research in cytology, genetics, molecular biology and
developmental biology.
9. Transmission of Diseases to animals and plants
Insects are
also important for our survival because they are responsible for transferring
some most important diseases in human as well as to animals. Many insects are
parasites of animals.
10. Predation
and Parasitism
Predatory
beetles and bugs are common in agriculture and often go unnoticed. But the valuable
service provided by them cannot be denied. If the populations of these
predators are disturbed as a result of chemical spray or some other practice
then the populations of insect pests of crop are liable to increase.
11. Maintaining
Plant Community Structure
Insects maintain
the plant community structure through feeding on plants, plant parts and seeds;
hence keeping a check and balance on natural habitats.
12. Critical
Ecological Services
In the tropical
areas, termites degrade woods to improve soil structure. Similarly, insect
larvae in sea add to the organic matter of water bodies by the degradation of
leaves and wood from the nearby terrestrial plants and add nutrients to water.
Hence there is more to entomology than we ever thought before. It is an interesting field of botany that cannot be ignored and must be well communicated to agriculturists because importance of insects cannot be denied in agriculture.
