*The carbon cycle includes the uptake of carbon dioxide by plants
through, its ingestion by animals and its release to the atmosphere
through respiration and decay of organic materials. Human activities
like the burning of fossil fuels contribute to the release of carbon dioxide
in the atmosphere. *The nitrogen cycle involves the uptake of nitrogen
form the atmosphere by a process called fixation which is carried out by
microbes or industrial processes. Decomposition of biological waste by
microbes can return nitrogen to the atmosphere. Nitrogen is mainly used
by humans as a fertilizer in farmlands, but its excessive usage can lead to
serious problems (such as eutrophication). Itrogen can be introduced
into the soil through natural process such as precipitation and lightning
(1), as well as through human means such as fertilizers (2). Plants and
animals cannot directly use atmospheric nitrogen (N2 gas) because it
does not easily react with other biological molecules. Because of this,
plants and animals need to get their nitrogen from more reactive
nitrogen compounds.In soil, specialized bacteria known as nitrogenfixing bacteria (3), are able to covert (or fix) atmospheric nitrogen into
more chemically-reactive nitrogen compounds such as ammonia (NH3)
and ammonium (NH4+). Other bacteria, called nitrifying bacteria (4) can
convert the ammonium in the soil into nitrite (NO2-) and then into nitrate
(NO3-).Nitrates can be taken up and used by plants (5) to make proteins.
As animals eat plants, the plant proteins are taken up by the animals (6).
When the animals make excrement (poop) (7) or when plants and
animals die (8), this matter is broken down by decomposers (9) and
ammonia is re-introduced into the soil. Denitrifying bacteria (10) convert
nitrates back to unreactive nitrogen which can be re-introduced back
into the atmosphere – and the cycle begins again. *The phosphorus cycle
involves the uptake of phosphorus by organisms. Phosphorus in the
environment is mainly found in rocks, and natural weathering processes
can make it available to biological systems. After decomposition of
biological waste, it can accumulate in large amounts in soils and
sediments. Phosphorus is used by humans as a fertilizer in farmlands and
in detergents. Overuse of phosphorus can lead to eutrophication.
Phosphorus is an essential element for all life. The way that phosphorus
is moved through plants and animals, the water, and soil is known as the
phosphorus cycle (Figure 3). The phosphorus cycle is a very slow
process.Phosphorus is mainly stored as phosphate ions (PO3−4) in water,
soil, rocks, and sediments. Most soils have very low amounts of
phosphate. Phosphorus can occur both as inorganic and organic
compounds. Inorganic phosphate ions can be distributed throughout soil
and water due to weathering and erosion Plants take up inorganic
phosphate from soil but since inorganic phosphorus is not very soluble in
water, only a small amount of the total phosphorus is available to plants.
When plants are eaten by animals phosphate can be used to build
organic molecules such as DNA and proteins. When a plant or animal
dies or an animal produces excrement organic phosphate is returned to
the soil. Mineralization occurs when bacteria break down organic matter
into
inorganic
phosphorus.
The
reverse
is
called
immobilization.Addition of fertilizers and decomposition of plants and
animals can increase the total phosphorus in the soil. The removal of
phosphorus from soil occurs mainly through plant uptake but can also
occur through leaching The leaching of excess phosphorus into
waterbodies can cause excessive growth of plants, leading to
eutrophication.* Western/ European Honey Bee – Apis mellifera Asiatic/
Asian Honey Bee – Apis cerana Red dwarf Honey Bee – Apis florae
Black dwarf Honey Bee – Apis andreniformis*Lentic region is defined as
the region in the water body, where the water does not have any flow,
and the water is stagnant, while the lotic region is defined as the region
in the water body, where water is in a continuous state of motion, which
means in the dynamic state. Lentic ecosystem (also called the lacustrine
ecosystem or the still water ecosystem) and lotic ecosystem (also called
the riverine ecosystem) are two types of water ecosystems, the first
dealing with still water ecosystems and the second dealing with flowing
water ecosystems. Together, they are the two ecosystems that make up
the study of freshwater ecology, also known as aquatic ecology.Lentic
featuresa lentic ecosystem entails a body of standing water, ranging from
ditches, seeps, ponds, seasonal pools, basin marshes and lakes. Deeper
waters, such as lakes, may have layers of ecosystems, influenced by light.
Ponds, due to their having more light penetration, are able to support a
diverse range of water plants.Lotic featuresa lotic ecosystem can be any
kind of moving water, such as a run, creek, brook, river, spring, channel
or stream. The water in a lotic ecosystem, from source to mouth, must
have atmospheric gases, turbidity, longitudinal temperature gradation
and material dissolved in it.* A food chain refers to the order of events in
an ecosystem, where one living organism eats another organism, and
later that organism is consumed by another larger organism. The flow of
nutrients and energy from one organism to another at different trophic
levels forms a food chain.The food chain also explains the feeding
pattern or relationship between living organisms. Trophic level refers to
the sequential stages in a food chain, starting with producers at the
bottom, followed by primary, secondary and tertiary consumers. Every
level in a food chain is known as a trophic level. The food chain consists
of four major parts, namely The Sun: The sun is the initial source of
energy, which provides energy for everything on the planet. Producers:
The producers in a food chain include all autotrophs such as
phytoplankton, cyanobacteria, algae, green plants. This is the first stage
in a food chain. The producers make up the first level of a food chain.
The producers utilise the energy from the sun to make food. Producers
are also known as autotrophs as they make their own food. Producers
are any plant or other organisms that produce their own nutrients
through photosynthesis. For example, green plants, phytoplankton and
algae are some examples of producers in a food chain. Consumers:
Consumers are all organisms that are dependent on plants or other
organisms for food. This is the largest part of a food web, as it contains
almost all living organisms. It includes herbivores which are animals
that eat plants, carnivores which are animals that eat other animals,
parasites are those organisms that live on other organisms by harming
them and lastly the scavengers, which are animals that eat dead animals’
carcasses. Here, herbivores are known as primary consumers and
carnivores are secondary consumers. The second trophic level includes
organisms that eat producers. Therefore, primary consumers or
herbivores are organisms in the second trophic level. Decomposers:
Decomposers are organisms that get energy from dead or waste organic
material. This is the last stage in a food chain. Decomposers are an
integral part of a food chain, as they convert organic waste materials
into inorganic materials like nutrient-rich soil or land.Decomposers
complete a life cycle. They help in recycling the nutrients as they provide
nutrients to soil or oceans, that can be utilised by autotrophs or
producers. Thus, starting a whole new food chain.* The scientific name
of prawn is Dendrobranchiata (Suborder).* the most important
characteristics of population are as follows:Population density 2.
Natality 3. Mortality 4. Population growth 5. Age distribution of
population 6. Population fluctuations.* Human population growth
impacts the Earth system in a variety of ways, including:Increasing the
extraction of resources from the environment. These resources include
fossil fuels (oil, gas, and coal), minerals, trees, water, and wildlife,
especially in the oceans. The process of removing resources, in turn,
often releases pollutants and waste that reduce air and water quality,
and harm the health of humans and other species. Increasing the burning
of fossil fuels for energy to generate electricity, and to power
transportation (for example, cars and planes) and industrial
processes.Increase in freshwater use for drinking, agriculture,
recreation, and industrial processes. Freshwater is extracted from lakes,
rivers, the ground, and man-made reservoirs.Increasing ecological
impacts on environments. Forests and other habitats are disturbed or
destroyed to construct urban areas including the construction of homes,
businesses, and roads to accommodate growing populations.
Additionally, as populations increase, more land is used for agricultural
activities to grow crops and support livestock. This, in turn, can decrease
species populations, geographic ranges, biodiversity, and alter
interactions among organisms.Increasing fishing and hunting, which
reduces species populations of the exploited species. Fishing and hunting
can also indirectly increase numbers of species that are not fished or
hunted if more resources become available for the species that remain in
the ecosystem.Increasing the transport of invasive species, either
intentionally or by accident, as people travel and import and export
supplies. Urbanization also creates disturbed environments where
invasive species often thrive and outcompete native species. For
example, many invasive plant species thrive along strips of land next to
roads and highways.The transmission of diseases. Humans living in
densely populated areas can rapidly spread diseases within and among
populations. Additionally, because transportation has become easier and
more frequent, diseases can spread quickly to new regions.* catla (Catla
Catla), rohu (Labeo rohita) and (Cirrhinus mrigala)* An ecological
pyramid is a graphical representation of the relationship between the
different living organisms at different trophic levels. It was given by
G.Evylen Hutchinson and Raymond Lindeman.It can be observed that
these pyramids are in the shape of actual pyramids with the base being
the broadest, which is covered by the lowest trophic level, i.e.,
producers. The next level is occupied by the next trophic level, i.e., the
primary consumers and so on.All the calculations for construction of
these types of ecological pyramids must take into account all the
organisms in a particular trophic level because a sample space of a few
numbers or a few species will end up giving a huge level of errors Types
of Ecological pyramidecological pyramids can be of three kinds. These
are as follows:Pyramid of numberspyramid of biomasspyramid of
energthis ecological pyramid takes into account the number of
organisms present at each trophic level, making up that level for the
pyramid. The number of organisms decreases while going higher up the
pyramid. The ones at the bottom are the producers who are present in
the largest number and hence form the base of the ecological
pyramid. Pyramid of biomassthis ecological pyramid takes into
consideration the amount of biomass that is produced at each trophic
level as it adds to the pyramid. This pyramid is usually upright except for
exceptional cases like the marine ecosystem where the number of
phytoplanktons is lesser than the number of zooplanktons that depend on
them. The producers or the autotrophs have the highest level of biomass
in this pyramid. The next level of primary consumers have lesser biomass
than the producers and similarly, the secondary consumers have lesser
biomass than the primary consumers. As a result, the level of the
pyramid that has the least biomass is at the top of the pyramid. Pyramid
of energythis pyramid shows the flow of energy that is in the direction of
the consumers and comes from the producers. This pyramid is always in
an upright form since it signifies the flow of energy within a food chain,
something that is always unidirectional. The typical energy pyramid has
three levels: the producer level, the consumer level, and the decomposer
level. The flow of energy in an ecological pyramid is from bottom to top,
which means energy from the autotrophs, who are also the primary
producers, goes to the primary consumers, meaning those who consume
these plants. *Abiotic factors refer to non-living physical and chemical
elements in the ecosystem. Abiotic resources are usually obtained from
the lithosphere, atmosphere, and hydrosphere. Examples of abiotic
factors are water, air, soil, sunlight, and minerals. Biotic factors are
living or once-living organisms in the ecosystem. These are obtained
from the biosphere and are capable of reproduction. Examples of biotic
factors are animals, birds, plants, fungi, and other similar organisms.*
Biotic factors relate to all the living things in the ecosystem. Their
presence and their biological by-products affect the composition of an
ecosystem. Biotic factors refer to all living organisms from animals and
humans, to plants, fungi, and bacteria. The interactions between various
biotic factors are necessary for the reproduction of each species and to
fulfil essential requirements like food, etc.Examples of Biotic
factorsexamples of biotic resources include all the living components
present in an ecosystem. These include producers, consumers,
decomposers and detritivores.Abiotic factorsabiotic factors refer to all
the non-living, i.e. Chemical and physical factors present in the
atmosphere, hydrosphere, and lithosphere. Sunlight, air, precipitation,
minerals, and soil are some examples of abiotic factors. These factors
have a significant impact on the survival and reproduction of species in
an ecosystem.For instance, without an adequate amount of sunlight,
autotrophic organisms may not be able to survive. When these organisms
eventually die, it will create a shortage of food for primary consumers.
This effect cascades up the food chain, affecting every organism.
Consequently, it leads to an imbalance in the ecosystem.Examples
of Abiotic factorsabiotic examples typically depend on the type of
ecosystem. For instance, abiotic components in a terrestrial ecosystem
include air, weather, water, temperature, humidity, altitude, the ph level
of soil, type of soil and more. Abiotic examples in an aquatic ecosystem
include water salinity, oxygen levels, ph levels, water flow rate, water
depth and temperature.* All processes in this world, whether living or
non-living, need energy. Living organisms are capable of producing
energy or getting it through predation. They need this energy to maintain
cells and tissues. It is also required for supporting voluntary and
involuntary actions of the human body and other multiple processes
within the body like reproduction, cell division, metabolism, digestion,
circulation, excretion, and much more.The ultimate source of energy on
Earth is the Sun. No energy can be produced without the sun. All living
beings, especially plants capture solar energy and utilise it for their food
production. This process is called photosynthesis.What is Food
Web?There are unique interactions and relationships which are involved
in the transportation of energy. The energy, once produced and
captured, is distributed throughout the various living organisms. This
transfer of energy is termed as the food web.* International Union for
Conservation of Nature (IUCN) enlisted some species as endangered
species. Endangered species can be defined as those species which are
under risk or threat of being extinct. In other words, species which are
about to extinct. Many factors are responsible for this which may be
natural or man-made. Endangered species, sooner or later enter the
extinction phase. In order to prevent this, necessary actions have to be
taken.A species which was native to a region and its population strength
reduced from 50 percent to 5 percent; such species are known are
endangered species. IUCN categorized them and made a list called red
list. Another document which consists of a list of rare and endangered
species in an area was established by the Russian federation. This book
is known as Red Data Book. These documents consisting of a list of
species are used as a guide for researchers to estimate the level of threat.
There are separate books for both flora and fauna*Difference Between
Wildlife Sanctuary and National parkthe points mentioned below
elaborate the difference between the national park and wildlife
sanctuary:Wildlife sanctuary consists of the areas where wildlife and
their habitat are preserved from any sort of disturbance. On the other
hand, a national park is the region of the countryside that is specially
allocated for wildlife, in which they can live and consume the natural
resources with freedom.Wildlife sanctuaries are known for wildlife
conservation, which consists of insects, animals, birds, and
microorganisms of various species and genes. Conversely, national
parks are majorly famous for protecting the fauna, flora, landscape, and
historical entities.The objective of wildlife sanctuaries is to ensure that a
population of the wildlife and their habitats are maintained substantially.
Whilst, national parks preserve the scenic, environmental, and cultural
heritage of the territory.Talking about restrictions, national parks are
significantly restricted regions, which are open only to certain people,
while wildlife sanctuaries have lesser restrictions as compared to
national parks.To visit national parks, you need to have official
permission to be received from the relevant authorities. On the contrary,
no official permission is required to visit a wildlife sanctuary.Boundaries
of wildlife sanctuaries are not specified, while they are clearly marked in
the national parks.Human activities are allowed to some extent in the
wildlife sanctuaries, while in the case of national parks, they are strictly
banned by the governing authorities. *Insects aphidsaphids are 1–3mm,
soft-bodied insects that can be green, grey, or black. Most commonly
seen in spring and autumn, aphids can be winged or wingless and are
usually slow-moving. Aphids cluster on the tips of the shoots, sucking the
sap from the plant, which reduces plant vigour. Aphids can also spread
viruses which can severely reduce yields and quality. A number of
natural enemies such as lacewings and ladybugs will give some
biological control. If required, control with sprays such as garlic extract
or horticultural oils and horticultural soaps. Sprays containing
pyrethrum and piperonyl butoxide can also be used but crops can not be
picked for one day after its use.caterpillarscaterpillars are usually the
larval stages of moths or butterflies. They are normally hairless, with a
long cylindrical body from 10–50mm long and range in colour.
Caterpillars may attack leaves, stems, flowers, fruits and roots.Green
caterpillars of the large cabbage white butterfly and the small diamondback (cabbage) moth can severely damage the leaves of the Brassica
family which includes broccoli, cabbage, kale and cauliflower.Cluster
caterpillars, woolly bear caterpillars and looper caterpillars will attack
the leaves of most vegetables.* Granary weevil (Sitophilus
granarius)When disturbed it sits very still for several minutes. An adult
lays up to 450 eggs singly in holes chewed in cereal grains. Each egg
hatches into a white, legless larva, which eats the grain from the inside.
The larva pupates within the grain and the adult then chews its way out.
The exit holes are characteristic signs of weevil damage. The life cycle
takes about one month under summer conditions and adults may survive
for a further eight months. The granary weevil is a small dark brownblack beetle about 4mm long with a characteristic rostrum (snout)
protruding from its head. It has biting mouth parts at the front of the
rostrum and two club-like antennae.Rice weevil (Sitophilus oryzae)An
adult lays up to 450 eggs singly in holes chewed in cereal grains. Each
egg hatches into a white, legless larva, which eats the grain from the
inside. The larva pupates within the grain and the adult then chews its
way out. The exit holes are characteristic signs of weevil damage. The
life cycle takes about one month under summer conditions and adults
may survive for a further eight months. The rice weevil has four orangebrown areas on the wing cases, and is about 3mm long with a
characteristic rostrum (snout) protruding from its head. It has biting
mouth parts at the front of the rostrum and two club-like antennae.
Unlike the granary weevil, the rice weevil is winged and may
occasionally fly.* Ex-situ conservationin this type of conservation, the
threatened animals and plants are taken out from their natural habitat
and placed in a special area or location where they can be protected and
given special care. For example - zoological parks, botanical gardens,
wildlife safari parks, gene banks, germplasm banks, and seed
banks.Many animals have become extinct in the wild but few of them are
kept in zoological parks. The gametes of threatened species can be
preserved in viable, fertile conditions for long periods using
cryopreservation techniques, In this, the eggs can be fertilized in vitro,
and plants can be propagated using tissue culture methods. Seeds of
different genetic strains of commercially important plants can be kept for
long periods in seed banks.B. In-situ conservationin this type of
conservation method, species are protected in their natural habitat by
making their habitats protected areas. For example- national parks,
sanctuaries, biosphere reserves, etc.Types of In-Situ Conservation
Areas National Parks: These areas are maintained by the government
and reserved for the betterment of wildlife, cultivation, grazing, forestry;
and habitat manipulation is not allowed.Sanctuaries: They are tracts of
lands with or without lake share where wild animals/fauna can take
refuge without being hunted. Other activities like collection of forest
products, harvesting of timber, private ownership of lands, tilling of
land, etc. Are allowed.Biosphere Reserves: They are multipurpose
protected areas that are meant for preserving genetic diversity in
representative ecosystems of various natural biomes and unique
biological communities by protecting the wild populations, traditional
lifestyles of tribals,, and domesticated plant/animal genetic resources.
They are specified protected areas in which multiple uses of the land are
permitted. *Marine ecosystems are aquatic environments with high
levels of dissolved salt, such as those found in or near the ocean. Marine
ecosystems are defined by their unique biotic (living) and abiotic
(nonliving) factors. Biotic factors include plants, animals, and microbes;
important abiotic factors include the amount of sunlight in the
ecosystem, the amount of oxygen and nutrients dissolved in the water,
proximity to land, depth, and temperature.Sunlight is one the most
important abiotic factors for marine ecosystems. It’s so important that
scientists classify parts of marine ecosystems—up to three—by the
amount of light they receive. The topmost part of a marine ecosystem is
the euphotic zone, extending down as far as 200 meters (656 feet) below
the surface. At this depth, there is sufficient light for regular
photosynthetic activity. Most marine life inhabits this zone. Below the
euphotic zone is the dysphotic zone, which can reach from 200 to as deep
as 1,000 meters (656 to 3,280 feet) below the surface. At these depths,
sunlight is still available, but only enough to facilitate some
photosynthesis. Below the dysphotic zone lies the aphotic zone, which
does not receive any sunlight. Marine Ecosystem animalsmarine
ecosystems support a great diversity of life with a variety of different
habitats. They can be categorized into groups based on where they live
(benthic, oceanic, neritic, intertidal), as well as by shared characteristics
(vertebrates, invertebrates, plankton). Specific examples of marine
animals include sea urchins, clams, jellyfish, corals, anemones,
segmented and non-segmented worms, fish, pelicans, dolphins,
phytoplankton, and zooplankton.Marine Ecosystem plantsyou can find
many types of plants in the ocean, including seaweeds, algae (red, green,
brown), sea grasses (the only flowering plants in the marine ecosystem),
and mangroves.Marine Ecosystem climatesmarine ecosystems are found
on many different parts of the Earth, so it shouldn’t be surprising to
learn that marine climates can vary from tropical to polar. Other
climates found in marine ecosystems include monsoon, subtropical,
temperate, and subpolar. *Energy flowthe chemical energy of food is the
main source of energy required by all living organisms. This energy is
transmitted to different trophic levels along the food chain. This energy
flow is based on two different laws of thermodynamics:First law of
thermodynamics, that states that energy can neither be created nor
destroyed, it can only change from one form to another.Second law of
thermodynamics, that states that as energy is transferred more and more
of it is wasted.Energy Flow in ecosystemthe energy flow in the ecosystem
is one of the major factors that support the survival of such a great
number of organisms. For almost all organisms on earth, the primary
source of energy is solar energy. It is amusing to find that we receive less
than 50 per cent of the sun’s effective radiation on earth. When we say
effective radiation, we mean the radiation, which can be used by plants
to carry out photosynthesis. Most of the sun’s radiation that falls on the
earth is usually reflected back into space by the earth’s atmosphere. This
effective radiation is termed as the Photosynthetically Active Radiation
(PAR).Overall, we receive about 40 to 50 percent of the energy
having Photosynthetically Active Radiation and only around 2-10
percent of it is used by plants for the process of photosynthesis. Thus,
this percent of PAR supports the entire world as plants are the producers
in the ecosystem and all the other organisms are either directly or
indirectly dependent on them for their survival.The energy flow takes
place via the food chain and food web. During the process of energy flow
in the ecosystem, plants being the producers absorb sunlight with the
help of the chloroplasts and a part of it is transformed into chemical
energy in the process of photosynthesis.This energy is stored in various
organic products in the plants and passed on to the primary consumers
in the food chain when the herbivores consume (primary consumers) the
plants as food. Then conversion of chemical energy stored in plant
products into kinetic energy occurs, degradation of energy will occur
through its conversion into heat.Then followed by the secondary
consumers. When these herbivores are ingested by carnivores of the first
order (secondary consumers) further degradation will occur. Finally,
when tertiary consumers consume the carnivores, energy will again be
degraded. Thus, the energy flow is unidirectional in nature.Moreover, in
a food chain, the energy flow follows the 10 percent law. According to
this law, only 10 percent of energy is transferred from one trophic level
to the other; rest is lost into the atmosphere. This is clearly explained in
the following figure and is represented as an energy pyramid.* Natural
resources are the ones that come from nature. People cannot make
natural resources, however, they can collect them. Some of the examples
of natural resources include water, coal, wood, and iron. Some of the
resources, for example, hydroelectric energy are not considered to be
natural since they are made by people.Classifications of Natural
resourceslet us now look at how natural resources are classified.Natural
resources are mainly classified into 2 different categories:Renewable
natural resources andnon-renewable natural resourcesrenewable
natural resources are the resources that can be generated again once
they are used. Some of the examples of renewable natural resources
include sunlight, water, and wood. Non-renewable natural resources are
the ones that exhaust after their frequent usage and sometimes it takes a
really long time for them to regenerate. An example of this includes
natural gas. Another example of a non-renewable natural resource is
coal. Just as coal, there are many such natural resources that are limited
which means that they cannot be recycled again. Most of these nonrenewable natural resources cannot be recycled and hence it is
important to conserve these natural resources. There are several natural
resources that have a very high demand but have a lesser availability. It
is highly important that we conserve these natural resources since they
are getting exhausted at an alarming rate. Apart from that, it has an
adverse effect on the environment that is indirectly causing harm to
living beings. However, if we follow some tips in our day to day lives, we
can conserve these natural resources.Use an alternative source of power
like solar and wind energyplant more trees for preventing the soil
erosionuse pipelines for transporting oiltreat the industrial sewage and
wastage even before they get released into the water bodiesinclude the
rainwater harvesting system in the houseuse biogas in the houseuse
biofuels instead of the conventional petroleum-based fuelsensure that the
wastes are being recycleduse electronic mailsmake use of the energysaving tube lights and bulbspractice the method of crop
rotationconstruct reservoirs*An aquarium is a glass container which
displays the aquatic organisms in a simulated natural environment by
introducing aquatic plants, rocks, gravels, artificial decorative etc.
Maintenance of physico-chemical and biological parameters of water
inside the aquaria is of utmost importance. Different types of equipments
are required for controlling aeration, water movement, temperature,
suspended organic matter, illumination etc inside the aquaria.Utmost
care should be taken while feeding aquarium fishes. Over feeding is
always harmful to fishes. In effect, an aquarium is a biological entity.
Each of its elements – water,glass, light, sand, gravel, plants, fish, make
a harmonious whole, with the same ecological balance as exists in
nature. The aquarium should not be left uncared for a long time. Do not
over feed the aquarium fishes. Once the aquarium is set and balanced,
the water should not be changed unless it tends to become turbid or
cloudy. When the level of water falls in course of time, it should be
restored by addition of some rain water or chorine free tap water.
Overcrowding of fishes should always be avoided. For tropical fishes, a
temperature of around 720 F and ph of around 7 - 7.2 is ideal. In
changing the water of aquarium, a constant flow should be maintained
with help of tubes. Aerator should also be frequently operated. Fishes
should be subjected to kmno4 or cuso4 bath before keeping the in
aquarium. Aquarium should be filled by water to about three fourth of its
capacity. One type of food should not be used. Infected fishes should be
immediately removed. An aquarium should always be provided with a
cover.* In nature, Asia is the major manufacturer of silk in the world and
produces in excess of 95% of the entirety global output. Some of the
countries which give important for producing silk are China, India,
Japan, Brazil and Korea. India is the leading manufacturer of silk and
also have largest consumer of silk in the world. India has a well-built
tradition and culture bound home market of silk. In India, mulberry silk
is produced mainly in the states of Karnataka, Andhra Pradesh, Tamil
Nadu, Jammu & Kashmir and west Bengal. The non-mulberry silks are
produced in the state like Jharkhand, Chhattisgarh, Orissa and northeastern states. In nature, Asia is the major manufacturer of silk in the
world and produces in excess of 95% of the entirety global output. Some
of the countries which give important for producing silk are China,
India, Japan, Brazil and Korea. India is the leading manufacturer of silk
and also have largest consumer of silk in the world. India has a wellbuilt tradition and culture bound home market of silk. In India, mulberry
silk is produced mainly in the states of Karnataka, Andhra Pradesh,
Tamil Nadu, Jammu & Kashmir and west Bengal. The non-mulberry
silks are produced in the state like Jharkhand, Chhattisgarh, Orissa and
north-eastern states.* Fresh waters are classified on the basis of their
mobility. Based on this, two types are identified. These are:Lotic fresh
waters: These include all running waters which can flow continuously in
a specific direction. In other words, these are flowing or running waters,
e.g. Rivers, springs and streamslentic fresh waters: These include
standing or stagnant waters. These waters do not flow nor move.
Examples of lentic fresh waters are lakes, ponds, swamps and
damscharacteristics of Fresh Water habitatsthe following characteristics
are associated with fresh water habitats:Low salinity: Fresh water
habitats normally contain very low level of salts. It has about 0.5% of
salt compared to about 3.5% for sea watersmall in size: Fresh water
habitat is usually very small compared to the ocean water which is about
75% of the earth surfacevariation in temperature: The temperature of
fresh water habitat usually varies with season and depth. Temperature at
the surface of the water varies slightly with that at the bottom of the
waterhigh concentration of oxygen content: Oxygen is usually available
in all parts of the fresh water especially in the surface of the
watershallowness of water: Most fresh water habitats are very shallow
hence sunlight can easily penetrate through the water to the
bottomseasonal variation: Some fresh water habitats like streams and
rivers normally dry up during the dry season while others have their
volume reduced. The volume of water in rivers also increases during the
rainy season. Turbidity and fast flow of rivers are also high during the
rainy season than in dry seasoncurrents: Currents can affect the
distribution of gases, salts and small organisms in fresh water habitats
such as rivers and streams*Naturally occurring plants, animals and their
species that are not cultivated / domesticated / trained are collectively
referred to as wildlife. Wildlife is important because:It brings in
ecological balance and maintains the food chain. Wildlife helps in
conserving species of a region. It also helps to produce various forest
produces and spices.* urbanization, the process by which large numbers
of people become permanently concentrated in relatively small areas,
forming cities.The definition of what constitutes a city changes from time
to time and place to place, but it is most usual to explain the term as a
matter of demographics. The United Nations does not have its own
definition of “urban” but instead follows the definitions used in each
country, which may vary considerably. The United States, for instance,
uses “urban place” to mean any locality where more than 2,500 people
live. In Peru the term is applied to population centres with 100 or more
dwellings.* Lac is the sticky resinous substance secreted by a tiny variety
of insects. Use and culture of lac and lac products began in India as
early as 1200 B.C. The word lac is derived from the Hindi word lakh,
which means hundred thousand indicating the large number of insects
required to produce recognizable quality of lac. About 17,000 to 90,000
insects are required to produce one pound of lac. The lac has been
referred in ancient Sanskrit works viz., Atharva-Veda and was called as
‘Luxa’. It is mentioned in Mahabharata that ‘Luxa Griha’ was made up
of lac, which was prepared by Kaurava for Pandavas. The deep crimson
coloured female after producing the required amount of lac stops feeding
and the body of the female shrinks considerably. It lays about 300-400
small, rounded eggs at a time and the female die leaving an encrustation
full of eggs. The eggs after sometimes change their colour and hatching
takes place after sometimes. Hatching is governed by the temperature
and humidity. Generally first brood comes in October or November. The
larvae emerge in a large number and come out of the encrustation. These
are small about .5 mm in size, red or pinkish red. They have a brood
middle region and tapering ends and resemble a pear shaped body. They
are provided with piercing and sucking type of mouthparts and ocelli.
The thorax and abdomen are well developed. The first instar larvae are
very sluggish and crawl a short distance only. They move in form of a
big crowd so it is named as “Swarming”. They prefer a newly emerged,
soft and succulent shoot where they can feed easily. The larvae settle
together in a large number in close association with each other.
Sometimes they are so close that the twig is not seen. They feed upon the
sap and secrete a pink coloured resin like substance from their dermal
glands. This becomes hard when comes in contact with air and is known
as lac. Lac deposition is done in all parts of the body except the
mouthparts, spiracles and anal pores. The so formed envelop is now
called “Cell” which protects the larva and all the post embryonic stages
are completed inside the cell. *In India, aquaculture has evolved from
just a backyard activity to an activity driven by technology and a
commercial business. Currently, India stands second in world
aquaculture production next to China. The following are the features
which played a major role in lifting the face of in India in commercial
aquaculture:Vast
untapped
surface
water
resources
Availability.Standardization of new production techniques.Extension of
technology and practical knowledge to the farmers through
governmental and non-governmental organizationsfinancial help for
aquaculture farmersin India large scale farming of Macrobrachium
rosenbergii is very popular. It is commonly called "Scampi". It has high
demand
in
both
domestic
and
international
markets.
*introductionbiological control is the use of living organisms to maintain
pest populations below damaging levels. Natural enemies of arthropods
fall into three major categories: predators, parasitoids, and pathogens
predatorspredators catch and eat their prey. Some common predatory
arthropods include ladybird beetles, carabid (ground) beetles,
staphylinid (rove) beetles, syrphid (hover) flies, lacewings, minute pirate
bugs, nabid bugs, big-eyed bugs, and spiders. Parasitoidsparasitoids
(sometimes called parasites) do not usually eat their hosts directly. Adult
parasitoids lay their eggs in, on, or near their host insect. When the eggs
hatch, the immature parasitoids use the host as food. Many parasitoids
are very small wasps and are not easily noticed. Tachinid flies are
another group of parasitoids. They look like large houseflies and deposit
their white, oval eggs on the backs of caterpillars and other pests. The
eggs hatch, enter the host, and kill it. Parasitoids often require a source
of food in addition to their host insect, such as nectar or pollen.
Pathogens are disease-causing organisms. Just as many other organisms
get sick, so do insects. The main groups of insect disease-causing
organisms are insect-parasitic bacteria, fungi, protozoa, viruses, and
nematodes. Biological control using pathogens is often called microbial
control. One very well-known microbial control agent that is available
commercially is the bacterium Bacillus thuringiensis (Bt). Because not
all formulations of Bt are approved for use in organic systems, it is
important to check with your certifier before using this. Several insectpathogenic fungi are used as microbial control agents, including
Beauveria, Metarhizium, and Paecilomyces. These are most often used
against foliar insect pests in greenhouses or other locations where
humidity is relatively high. Nuclear polyhedrosis viruses (NPV) and
granulosis viruses (GV) viruses are available to control some caterpillar
pests.* The life cycle of silk moth starts when a female silk moth lays
eggs. The caterpillar or larvae are hatched from the eggs of the silk
moth. The silkworms feed on mulberry leaves and give rise to pupa. In
the pupa stage, a weave is netted around by the silkworm to hold itself.
After that it swings its head, spinning a fibre made of a protein and
becomes a silk fibre. Several caterpillars form a protective layer around
pupa and this covering is known as the cocoon. The silk thread (yarn) is
obtained from the silk moth’s cocoon. The life cycle of the silkworm is
explained below in detail. Life Cycle of Mulberry Silkworm: The silk
moth is dioecious, i.e., the sexes are separate. Fertilisation is internal,
preceded by copulation. The development includes a complicated
metamorphosis. Eggs:After fertilisation, each female moth lays about
300 to 400 eggs. These eggs are placed in clusters on the leaves of
mulberry tree. The female covers the eggs by a gelatinous secretion
which glues them to the surface of the leaves. The eggs are small, oval
and usually slightly yellowish in colour. The egg contains a good amount
of yolk and is covered by a smooth hard chitinous shell. After laying the
eggs the female moth does not take any food and dies within 4-5 days. In
the univoltine (a single brood per year) they may take months because
overwintering takes place in this stage but the multivoltine broods come
out after 10-12 days. From the egg hatches out a larva called the
caterpillar. Larva: The larva of silkworm moth is called caterpillar
larva. The newly hatched larva is about 4.00 to 6.00 mm in length. It has
a rough, wrinkled, hairless and yellowish white or greyish worm-like
body. The full grown larva is about 6.00 to 8.00 cm in length. The body
of larva is distinguishable into a prominent head, distinctly segmented
thorax and an elongated abdomen. The head bears mandibulate mouth
and three pairs of ocelli. A distinct hook-like structure, the spinneret, is
present for the extrusion of silk from the inner silk-gland. The thorax
forms a hump and consists of three segments. Each of the three thoracic
segments bears pair of jointed true legs. The tip of each leg has a
recurved hook for locomotion and ingestion of leaves. The abdomen
consists of ten segments of which first nine are clearly marked, while the
tenth one is indistinct. The third, fourth, fifth, sixth and ninth abdominal
segments bear ventrally a pair of un-jointed stumpy appendages each.
These are called pro-legs or pseudo-legs. Each leg is retractile and more
or less cylindrical. The eighth segment carries a short dorsal anal horn.
A series of respiratory spiracles or ostia are present on either lateral
side of the abdomen. The larva is a voracious eater and strongly
gregarious. In the beginning chopped young mulberry leaves are given
as food but with the advancement of age entire and matured leaves are
provided as food. The caterpillar moves in a characteristic looping
manner. The larval life lasts for 2-3 weeks. During this period the larva
moults four times. After each moult, the larva grows rapidly. A fullgrown larva is about 8.00 cm long and becomes transparent and golden
brown in appearance. A pair of long sac-like silk-glands now develops
into the lateral side of the body. These are modified salivary glands.
Pupa: The full-grown larva now stops feeding and hides itself in a corner
under the leaves. It now begins to secrete the clear and sticky fluid of its
salivary glands through a narrow pore called the spinneret situated on
the hypo pharynx. The sticky substance turns into a fine, long and solid
thread or filament of silk into the air. The thread becomes wrapped
around the body of the caterpillar larva forming a complete covering or
pupal case called the cocoon. The cocoon-formation takes about 3-4
days. The cocoon serves a comfortable house for the protection of the
caterpillar larva for further developmentthe cocoon is a white or yellow,
thick, oval capsule which is slightly narrow in the middle. It is formed of
a single long continuous thread. The outer threads, which are initial
filaments of the cocoon, are irregular but the inner ones forming later
the actual bed of the pupa, is one long continuous thread about 300
metres in length, wound round in concentric rings by constant motion of
the head from one side to the other about 65 times per minute. Imago or
Adult: The adult moth emerges out through an opening at the end of the
cocoon in about 2 to 3 weeks time, if allowed to live. Immediately before
emergence, the pupa secretes an alkaline fluid, that softens one end of
the cocoon and after breaking its silk strands, a feeble crumpled adult
squeezes its way out. Soon after emergence, the adult silk moths mate,
lay eggs and die.Economic Importance of Mulberry Silkworm: The
mulberry silkworm moth is a very useful and valuable insect. It provides
two very important products such as silk and gut to the mankind.