7.1 Butterflies

Insects are the most abundant group of animals. They account for nearly three quarters of all life forms on earth. Their body is divided into three segments: head, thorax and abdomen. All insects have three pairs of legs and usually two pairs of wines.

Butterflies are among the most beautiful and frequently seen insects. The zoologoical order of Lepidoptera (Lepidoptera "scale wing") includes butterflies (sub-order Rhopalocera) and moths (sub-order Heterocera). Lepidoptera contains as many as 120,000 species: 100,000 species of moths and 20,000 species of butterflies.

Seven percent of the world's butterflies occur in India (1,400 species). In India, the maximum butterfly diversity occurs in the Western Ghats and Eastern Himalayas. The wide range of habitats in the Western Ghats is the reason for the rich butterfly fauna that occurs here. All ten butterfly families found in India are represented in the Western Ghats, and practically all butterflies recorded in South India occur here. Nilgiri and the hill ranges of the Kanara region of Karnataka are particularly rich. Both the largest Indian butterfly (Common Birdwing) and the smallest (Southern Grass Jewel) occur in the Western Ghats.

Butterflies

Value of butterflies

· Butterflies pollinate flowers and help plants produce fruit and seeds.

· Some species of butterflies are poisonous. They are being studied to produce ecologically safe pesticides. Certain species are used for experiments in genetic engineering.

· Butterflies-and especially caterpillars, their larval form-are important sources of food for other animals such as birds.

· Butterflies add color to wilderness areas in the Western Ghats.

· Some butterfly caterpillars are pests on cultivated crops.

Suggested reading

Gay, Kehimkar and Punetha. Field guide to common Indian butterflies. WWF-India.

Wynter-Blyth. Butterflies of the Indian Subcontinent. Bombay Natural History Society.

Mimicry in butterflies

Some butterflies mimic other species to protect themselves from predators. Two types of mimicry are:

· Batesian mimicry: Edible species look like inedible species. E.g., the Common Mormon mimics the Crimson Rose.

· Mullerian mimicry: Two or more inedible species look alike. E.g., the Striped Tiger and Plain Tiger look similar.

Inedible species are normally brightly colored (red and black, orange, blue and black). They contain toxic chemicals.

Some butterflies and larvae resemble non-living things. For instance, the Oakleaf butterfly resembles a dried leaf; the Common Mormon larva resembles a bird dropping.

Life cycle of butterflies

Threats

· Habitat destruction in the Western Ghats is probably the single most important threat to butterflies. Some butterflies rely only on certain plants; for instance, the Plain Tiger lays its eggs on the Giant Milkweed-larvae hatch and feed only on these plants. If a plant species disappears, the butterfly species that depends on it may also be eliminated.

· People like to collect butterflies as ornaments and wall hang ings. Over-collection, especially of large, colorful butterflies, threatens many species. Both commercial and casual collectors are to blame.

Conservation

· Preserve the habitat in the Western Ghats. This is no doubt the best way of saving many species of butterflies.

· Educate people on the role and importance of butterflies and discourage collection.

Butterfly farms

Butterfly farms are a unique and interesting way to introduce butterflies to people and breed endangered species in captivity.

A butterfly farm is an enclosed area which houses a variety of butterflies. Conditions to sustain these beautiful insects are artificially provided. Visitors can enter the farm and experience the thrill of butterflies sitting on their shoulder or head. Singapore, Malaysia, Papua New Guinea, the United Kingdom and the United States have butterfly farms.

Some butterflies of the Western Ghats

Common Birdwing
Common Mormon
Common Rose
Five-bar Swordtail
Emigrants
Lemon Pansy
Gray Pansy
Common Leopard
Tamil Lacewing
Black Rajah
Eggflies
Southern Rustic
Common Evening Brown
Common Pierrot
Southern Grass Jewel
Striped Tiger
Common Crow
Orange Tips
Blue Mormon
Crimson Rose
Common Banded Peacock
Common Jezebel
Grassyellows
Yellow Pansy
Common Sailer
Tree Nymph
Common Nawab
Baron
Castors
Tawny Coster
Bushbrowns
Common Cerulean
Plain Tiger
Blue Tiger
Skippers
Red Helen

Butterfly or moth?

Butterfly

· clubbed antennae
· most are diurnal

Moth

· tapering or feather-like antennae
· most are nocturnal

Butterfly or moth?

Prepared by Srinivasan Karthikeyan

7.2 Honeybees to conserve biodiversity

Bee-plant relationships

Bees and plants have co-existed since time immemorial. Bees depend for their food on plants: nectar provides them with carbohydrate, while pollen supplies protein. Most bees also depend on plants for shelter. In return, bees help with the vital process of plant reproduction. They cross-pollinate flowers, diversify the genetic background of seed, and help plant species reproduce and survive.

Bees can distinguish colours, shapes and scents of flowers. They cannot see red but do perceive ultraviolet light. Bees can reach the concealed nectar in flowers that have intricate structures. Their sense of time means they can accurately visit flowers when nectar is secreted and pollen grains are produced.

Bees have adjusted themselves to evolutionary changes in flowers. They have in turn influenced the evolution of flowers, causing the flowers to become more complex in colour, shape and structure, reducing the number of floral parts, and influencing the production and protection of nectar.

Many flowers have complicated ways of providing access to pollen and nectar. These reward pollinat ing insects but discourage others. The floral structures and the chemical composition of the food are adapted to the senses of certain pollinating insects. Protein-rich pollen and glucose-rich nectar are most sought after by trees

Bees need a clean and healthy environment. The existence of natural bee colonies is a good indicator of a healthy environment. Individual bees can also be useful in detecting air pollution.

Bee-plant relationships

Four species of honeybee

India can boast of being a centre of origin of the world's honeybee species. Out of the five honey-producing bee species, four have occurred in India since ancient times. They are also found in the Western Ghats.

Apis dorsata-the rock bee or giant bee

This wild bee constructs single, huge, vertical wax comb exposed to light. The nest hangs on tall tree branches or towers, or underneath bridges or on rock cliffs. It contributes nearly 75% of total honey production of India. It migrates with the season to seek food and shelter.

Apis dorsata

Apis florea-the garden bee or little bee

This wild bee constructs a single, small, vertical comb in bushes exposed to light. It produces small quantities of honey. It also migrates depending upon the availability of food and shelter.

Apis florea

Apis cerana-indica the Indian hive bee

This hive bee constructs several vertical parallel combs in dark enclosures like hollows in tree trunks or in the ground. It is relatively stationary and can be kept in wooden hives for commercial production of honey and pollination services.

Apis cerana

Trigona irridipenis-stingless bee or dammer bee

Like the hive bee, this wild species occurs in dark enclosures, but it does not construct parallel combs. It builds nests comprising of clusters of cells meant for brood rearing and storage of honey and pollen. These bees are very small-little bigger than mosquitoes.

Trigona irridipenis

Upset balance

Bees are part of the delicate balance in the ecosystem. Human interference can upset this balance and disturb bee populations. On the Mahabaleshwar Plateau, for instance, natural honeybee colonies are reduced to dangerously low levels. In the 1950s and 1960s, natural bee colonies were abundant on the plateau; later local beekeepers found it difficult to procure natural colonies. Deforestation has depleted honey production to such an extent that traders now have to procure honey from other states. What applies to Mahabaleshwar is also the case in many other honey-producing regions in the Western Ghats.

Reduced numbers of colonies of Apis cerana, the Indian hive bee, are also due to human interference. In the 1970s, thousands of colonies were lost in an epidemic of a bacterial disease. An exotic species, the European honeybee (Apis mellifera), was imported into the Mahabaleshwar region, thereby introducing European foul brood disease. More recently, an outbreak of a viral disease took a large toll of bee colonies in many parts of Karnataka and Kerala.

Like the Indian hive bee, the wild migratory species A. dorsata and A. florea are also endangered by deforestation and thoughtless honey collection. Crude honey collection methods not only reduce the quality of honey but also damage hives and harm the bee population.

Beekeeping in Goa, Karnataka and Maharashtra

	Goa	Karnataka	Maharashtra	India
No. of beekepers	28	29,340	2,623	242,644
No. of colonies	22	139,916	4,041	1,075,241
Honey (kg)	18	602,570	78,244	928,429
Honey per colony (kg)	0.6	4.2	19.4	8.6

The queen is the only fully developed female in the colony. It lays eggs which hatch to increase the population.

Queen

The workers are the bees seen busily going in and out of the hive carrying food. They are females, but are not fully developed sexually. They do not lay eggs. Whether an egg grows into a queen or worker depends on the food given to the larva that hatches from the egg.

Workers

The drones are male members of the colony. Their sole function is to mate with the queen.

Drones

Maintaining biodiversity

Capacity to produce honey, disease resistance, low tendency to abscond or migrate, and mild temper leading to few stings are a few desirable traits the beekeeper seeks in bees. It is possible to breed superior strains of Indian hive bees. Local bee species should be used rather than imported exotic bees which may introduce diseases.

Suitable techniques for collecting honey and wax from wild bee species (Apis dorsata, A. florea and Trigona irridipenis) are needed. The Central Bee Research Institute in Pune has been successful to a great extent in this regard. Besides honey, all three species produce wax, pollen, royal jelly and bee venom. These species are immensely important in pollinating flowers. A. dorsata has a longer flight range, while A. florea can work on smaller flowers. Apis indica can be kept for pollination in agricultural or horticultural fields.

Beekeeping

Indian hive bee colonies can be procured and kept in modern wooden hives at desired locations, called apiaries. These locations should have ample flowers, shelter and a water source nearby. Little investment is necessary for the hives. Bees use readily available natural food. They do not compete with any agricultural animal for food and do not damage flora.

With an initial investment of about Rs 4000 for ten boxes and bee colonies, a beekeeper can earn around Rs 2000 per year by producing honey or multiplying bee colonies. Products such as beeswax can also be sold. Children, aged persons, men and women can maintain bee colonies. It requires no hard work or large amounts of time.

Chemical composition of pollen and honey

Pollen
Carbohydrates	35%
Proteins	20%
Fats	15%
Vitamins B. C, D, E
Water	15%
Minerals	10 types
Free amino-acids	10 types
Enzymes	10-15 types
Honey
Fruit sugars
(fructose)	40%
Glucose	35%
Sucrose	4%
Minerals, proteins, vitamins, acids, colouring matter, flavors	1%

Prepared by K. K. Kshirsagar

7.3 Mulberry silkworms

Silk-that beautiful, light cloth made into the most expensive saris-has humble origins. It is produced by insects called silkworms as a vital part of their growth.

Silkworms are the larvae or caterpillars of silk moths. When the time comes for the larva to change into its next growth stage, a pupa, it secretes a long thread of sticky silk. It forms this into a cocoon around itself. Inside the protective cocoon, the larva gradually metamorphoses. After 8-12 days, a moth emerges.

Silkworms are fed a diet of mulberry leaves grown especially for this purpose. The practice of raising silkworms is called "sericulture". This industry has led to the diversification of silkworm races and of the mulberry trees used to feed them. It has not so far led to major negative impacts on the wild races of either the silkworms or trees.

Industrious insects

Many insects are useful to humans, but only two are reared on a large scale: silkworms and honeybees.

Life cycle of the silkworm

Ten species of butterflies produce silk, but only five spin silk that can be wound onto a reel: the Mulberry silkworm, Eri, Muga, Tasar and Anaphe. By far the most important is the Mulberry silkworm, which produces 92% of the world's silk output. This silkworm is the only species widely reared for commercial use. It has been domesticated for so long that it can no longer survive in the wild.

The silk from silkworms is used for making cloth because of its beauty, strength, softness and durability.

Silkworms

The Western Ghats has a wide range of silkworm races. The most commonly used is Pure Mysore, or PM for short. This race is hardy and resists diseases.

Silkworm races differ in certain important characteristics of interest to sericulturists:

· Voltinism: The number of generations completed by an organism in a year is known as "voltinism". Univoltines complete one life cycle (from egg to adult to egg) in one year. Bivoltines complete two such cycles, and multivoltines (or polyvoltines) complete more than two. In the Western Ghats region, people use bivoltine silkworms such as Kalimpong-A (also known simply as KA), as well as multivoltines (such as Pure Mysore).

· Moultinism: This is the number of times the larva moults during its lifetime. Different races of silkworms moult as many as six times or just twice. In the Western Ghats, only those that moult four times are used because they are most economical.

· Place of origin: Silkworm races are classified as Japanese, Chinese, European and Southeast Asian. Western Ghat sericulturists make use of all except the European races because these require colder temperatures.

· Cocoon shape: Different silkworms spin cocoons of different shapes. Silkworms spin round, oval, dumbell- and spindle-shaped cocoons. All of these types are raised in the Western Ghats.

· Cocoon colour: Different silkworms spin cocoons of various hues: white, green, yellow, golden and flesh. In the Western Ghats, KA, NB7 and NB4D2 races spin white silk; PM spins green cocoons.

Silk

The cocoons of insects and webs of spiders consist of light, but extremely strong threads. A mulberry silk thread is stronger than a steel wire of the same thickness.

The raw silk is spun into threads and woven into very light, fine cloth. Because silk is highly elastic, it can be woven into a wide range of cloth types, including satin, crepe and voile.

The Western Ghats states-Maharashtra, Karnataka, Kerala, part of Tamil Nadu and, of late, Goa-produce more than 60% of India's silk output. Silviculture is also being introduced in new areas, such as Sirsi Siddapur (North Kanara).

Cocoon shapes and silkworm races

Breeding silkworms

Sericulturists face various problems with existing types of silkworms:

· Lack of seasonal and regional silkworm races.
· Lack of hardy, productive, disease-resistant silkworm races.
· Shortage of bivoltine breeds (that produce two generations a year).

More silkworm breeds should be bred to give rearers a choice of the most suitable race for particular situations. Some 34 desirable characteristics have been identified. Breeding is difficult because almost all of these characteristics are controlled by more than one gene. This makes ii impossible to develop a silkworm race with all the good characters. Researchers are trying to breed races that have just one or two of tile desired characters. For instance, CAC and HR14 races are hardy and bivoltine; NCD has superior dumbbell-shaped cocoons; CDS2 is temperature tolerant. It is also necessary to conserve existing local races of silkworms to conserve the biodiversity of this important species.

Mulberry silkworm species

Bombyx mandarina (wild ancestor)*
Bombyx mori (currently used commercially)*
Bombyx textor
Bombyx croesi
Bombyx fortunatus bombyx arracanensis
Bombyx sinensis* (B. meridionalis)
Theophila religiosa
Rondotia menciana

* Found in the Western Ghats

Origins of silk

The silk industry originated 45 centuries ago using wild silkworms in North China along the banks of the Huang Ho river. In 195 AD sericulture was introduced to Korea and other places.

But Indian scholars point to ancient Sanskrit literature that refers to silk as chinon shuka. This appears to show that silkworms were domesticated independently in the foothills of the Himalayas.

Prepared by Dr. I. K. Pai

7.4 Spiders

Colourful web-weavers-and scary to some-spiders are little known or appreciated creatures. Like insects, they are invertebrates (they have no backbone). But they are not insects; rather, they are arachnids, related to scorpions, ticks, mites and king crabs.

There are 30,000 species of spiders distributed over 60 families worldwide. In India there are about 43 families of spiders.

Spiders inhabit a wide range of ecosystems because they can tide over periods of food shortage and take advantage of periods of abundance. In the Western Ghats, they are found in a variety of microhabitats-tree bark and trunks, rock crevices, under leaves and stones, below bushes, on walls of houses, in tunnels and burrows, and near water.

Spiders as big-control agents

Spiders are important biological control agents of animal and plant pests. The giant crab spider (Heteropoda venatoria) prefers cockroaches and other insects. Wolf spiders relish brown planthoppers-a pest dreaded by rice farmers.

Threats to spiders

· Many pesticides kill beneficial spiders as well as insect pests. Indiscriminate use can lead to increases in pest numbers because spiders and other predators are wiped out. Some species of spider may be endangered because of such use.

· As with all species, the destruction of habitat through deforestation and other changes may reduce the number of spiders.

· Many people are afraid of spiders. Instead of being seen as friends and vital parts of the ecosystem, spiders are often indiscriminately killed.

Conservation approaches

· Raise the general awareness of the important role spiders play in the Western Ghat ecosystem.
· Study spiders' role as big-control agents in agriculture.
· Explore various uses of silk-for instance, for fishing nets. The use of webs in bulletproof vests is being studied.
· Do not destroy forest patches-the home of many spiders.
· Study the role of spiders in maintaining the stability of an ecosystem and their relation to other forms of life.

Arachnids vs insects

Arachnids	Insects
8 legs	6 legs
2 body	3 body
parts:	parts: head,
cephalothorax,	thorax,
abdomen	abdomen
6-8 simple eyes	Compound eyes
No antennae	Antennae
Young resemble adults	Young differ from adults
Mature by moulting	Mature in stages

Arachnids vs insects

Uses of spider silk

· Tribal people in Australia and Papua New Guinea use the web of Nephila sp. to make fishing nets.

· Some tribal people in Maharashtra mix spider silk with jaggery to make native medicine to control fever.

· Spider silk is used as a healing agent in Unani medicine.

Some common spiders of the Western Ghats

Name	Family	Look for them...
Mygalomorp spiders	Thraphosidae	On the ground, in tree hollows and burrows
Argiope sp.	Araeneidae	Tree trunks, bushes
Gasteracantha sp.	Araeneidae	Low bushes and in trees
Herennia spider	Araeneidae	Walls of houses in forest, trunk of tree
Giant Wood spider	Araeneidae	Trees and bushes in thick forests
Social Web spider	Eresidae	Trees and bushes
Two-tail spider	Hersilidae	Tree trunk and walls of houses
Heteropoda spider	Heteropodidae	Cracks and crevices, in houses
Wolf spiders	Lycosidae	Base of tree trunks, under stones, in shrubs, on grasses, in tunnels and burrows
Lynx spider	Oxyopidae	Plant leaves, grass, shrubs
Dancing spider	Pholcidae	Tree hollows, corners of houses
Jumping spiders	Salticidae	Tree, bushes, inside houses
Tetragnatha spiders	Tetragnathidae	Inside wells, grasses near water
Crab spiders	Thomisidae	On flowers

Spider facts

· All spiders are carnivorous and feed only on living prey.

· Spider silk is a kind of protein, used not only for trapping prey but in egg cases, nest lining and as a food source.

· All spiders are poisonous to their prey. Only a few are highly venomous and can kill a human being.

· Spiders may live from several months to ten years in their natural habitats.

· All spiders are solitary except for the group known as "social web spiders", which live in colonies.

· Certain species of sunbirds use the nests of social web spiders for their nests.

Spider myths

The term Arachnidae is derived from the Greek Arachne, meaning spider. The legendary Arachne wove exquisite tapestries. She was invited to a weaving competition with the Goddess Athene, whom she defeated. The enraged Athene tore the tapestry and Arachne killed herself. It is said that Athene changed Arachne to a spider so that she could continue spinning beautiful tapestries!

Spiders are also mentioned in Hindu mythology as worshippers and protectors of Lord Shiva.

The jumping spider anchors itself to the ground with a silk thread before it jumps on its prey.

The jumping spider

By R. Bhanumati

7.5 Conserving natural enemies of mosquitoes

Mosquitoes are some of nature's most unloved creatures. Their bites itch, and they transmit dreaded diseases like malaria, filaria, dengue and Japanese encephalitis. Mosquitoes have enormous reproductive potential: if left unchecked, a female mosquito could produce 8 billion other females in only two months.

Fortunately, nature has provided a variety of biological control agents-pathogens, parasites and predators-that affect every stage of the mosquito's life cycle. They vary from micro-organisms to mammals such as bats, and even pitcher plants. Besides these natural enemies, abiotic factors such as temperature, humidity and rainfall also limit mosquito populations. The net result is to inflict considerable mortality on each generation of mosquitoes.

Threats to big-control agents

In the quest to eliminate insect pests of crops and insects that carry diseases, humans have resorted to the indiscriminate use of insecticides to support both agriculture and health.

Initial successes were tremendous. But through repeated use, the target insects (including mosquitoes) have gradually acquired physiological resistance to these insecticides. Many insecticides have a very broad-spectrum action, so they kill the natural enemies as well as the pests. And some pesticides enter the food chain, accumulate in the bodies of certain organisms, and disrupt the food web. These effects have caused incalculable harm to the natural enemies of mosquitoes and other insect pests.

Conserving, propagating and using biological control agents have gained tremendous importance. Chemical insecticides should be used only when absolutely essential, and then with extreme caution.

Promoting natural enemies

Mosquitoes have many natural enemies, but of this long list, only a few can be used on a large scale. These include toxins of bacteria (Bacillus sphaericus and Bacillus thuringiensis israeliensis) and certain types of fish.

Mosquito life cycle

Mosquitoes galore

A female mosquito lays on an average of 150 eggs every alternate day. Imagine a female lays eggs on 4 occasions in her life span (i.e., a total of 600 eggs) and half of the eggs hatch into females and the other half into males. After the 4th generation (i.e., in about two months), each female would theoretically produce 300 × 300 × 300 × 300 females, or about 8 billion females!

Natural enemies of mosquitoes Plants (Utricularia) Viruses Bacteria Fungi Protozoan parasites Nematodes (Romanomermis) Dragon fly adults Spiders Insects (Nepa sp., Notonecta sp.) Larvivorous fishes Frogs and toads Turtles Geckos House lizards Swallows Bats

Fish

Several indigenous species of fish have been identified and tested against mosquito larvae in Goal A small fish, Aplocheilus block) or "kankatre", is very effective at controlling mosquitoes and malaria. This fish is found throughout Goa in estuaries, fishponds, backwaters, lakes and streams. It is a much better predator of mosquito larvae than exotic species of fish such as Gambusia affinis (mosquito fish) and Lebistes reticulates (guppy). Aplocheilus block) is easily identified by the white spot between the eyes. Four to five fish per square metre surface area of water effectively control mosquitoes.

Another very agile, hardy and good larvivorous fish is Rasbora daniconius, or "dadiyo". These fish occur naturally in groups in ponds and streams. They are easily identified by a prominent dark line running from the operculum to the tail fin. People in Goa keep this fish in wells to keep the water clear of debris and the well walls free of algae and ferns. That they also predate upon mosquito larvae is not so well known. Two or three fishes per square metre of surface area can control mosquitoes in ponds, wells and tanks.

Aplocheilus blocki

Rasbora daniconius

Puntius ticto

Aplocheilus lineatus

Number of mosquito larvae consumed per day

Fish species	Max size (cm)	Larvae eaten per day, per gram fish weight
Aplocheilus block)	4	201
Lebistes reticulates	5	112
Gambusia affinis	8	138
Aplocheilus lineatus	10	78
Puntius ticto	10	126
Heteropneustes sp.	15	88
Oreochromis mossambicus	18	128
Rasbora daniconius	20	86

The bigger the fish, the more mosquito larvae it eats. But it is better to keep many small fish than a few large ones. The table above shows that in relation to their size, smaller fish eat more larvae than do bigger fish.

Frogs

Frogs are well-known big-control agents of insects. Adult frogs prey upon flying insects by shooting their sticky tongues out at the prey. The tadpoles devour aquatic insects, including mosquito larvae. Unfortunately, the number of frogs is dwindling because of insecticide use. Frogs are also hunted for their hind legs, which are considered a delicacy. Frogs can control mosquitoes in ponds. rice fields, lakes and water tanks. They are effective against mosquito vectors of Japanese encephalitis, particularly during the monsoon.

Frogs

Turtles

Many villagers in Goa keep freshwater turtles in their wells. The people believe they bring good luck and help keep the well water clean. Scientists in the Malaria Research Centre in Goa have found that turtles also control mosquitoes. In laboratory studies, fist-sized juvenile turtles can consume about 5000 mosquito immatures per day. Unfortunately, turtles are hunted for their flesh and carapace; their numbers have been dwindling very rapidly.

Turtles

Lizards

Lizards are often hated in the household as they are thought to be scary. A careful watch would show that they prey on various insects, including adult mosquitoes.

Lizards

Spiders

Spiders spin webs on walls, in corners and in dark, secluded places to trap their prey. Adult mosquitoes can often be seen trapped in the webs.

Spiders

Need to conserve natural enemies of mosquitoes

Research has shown the usefulness of larvivorous fishes and bacterial toxins in controlling mosquitoes and the diseases they spread. But we need to conserve and use natural control agents of mosquitoes at the household level. These friendly creatures face a constant dual threat from chemical insecticides and humans. It is common in Goa to see people hunting frogs for their hind legs immediately after the first pre-monsoon showers. The hunters fail to realise that killing frogs during this breeding season prevents them from producing offspring. Public awareness needs to be created to stop the slaughter of these friendly animals. Similarly, turtles also need to be protected. People should also use insecticides in a very selective and judicious manner to avoid harming big-control agents.

Some indigenous big-control agents of mosquitoes

Bio-control agents		Scientific/common name	Mosquito stage affected/killed
Pathogens	Viruses	Polyhydrosis	Larvae
	Bacteria	Bacillus sphaericus	Larvae
		Bacillus thuringiensis	Larvae
	Fungi	Coelomomyces indicus	Larvae
		Lagenidium giganteum	Larvae
		Metarhizium anisoplae	Larvae
		Tolypocladium cylindrosporum	Larvae
Parasites	Protozoa	Verticella microstoma	Larvae
	Nematodes	Romanomermis culcivorax	Larvae
	Mites	Hydracarine mites (Water mites).	Adults
Predators	Aquatic plants	Utricularia sp.	Larvae
	Coelentrates	Hydra cylindrica	Larvae
	Insects	Dystcidae larvae	Larvae
		Hydrophilidae larvae	Larvae
		Dragonfly adults	Adults
		Nepa (water scorpion)	Larvae
		Notonocta (water boatman)	Larvae
		Belostoma (giant water bug)	Larvae
		Hydrometra (water stick)	Larvae
		Gerris (pond skater)	Larvae
		Toxorhynchites splendens (mosquito larvae)	Larvae
	Spiders	Many species	Adults
	Larvivorous fishes	Aplocheilus block)	Larvae
		Aplocheilus lineatus	Larvae
		Rasbora daniconius	Larvae
		Danio asquipinnatus	Larvae
		Puntius ticto	Larvae
		Puntius amphiblus and many
		other species	Larvae
	Amphibians	Rana tigrina	Adults & larvae
		Bufo sp.	Adults & larvae
	Reptiles	Common house lizards	Adults
	Turtles	Larvae
	Birds	Swallows	Adults
	Mammals	Bats	Adults

Prepared by Dr. Ashwani Kumar

7.6 Vermicomposting

Earthworms are among the most ancient of terrestrial animal groups. Originally they were marine animals. Fossils of Polychaete worms have been found in South Australia in Precambrian sediments 630-570 million years old. Today's earthworms belong to the Oligochaetes. The limits of evolutionary and ecological diversity must be defined by inherent limitations of their mechanical "design" and behavioral and physiological adaptability.

Earthworms are traditionally used in domestic compost heaps and earth toilets. People are now looking for ways to dispose of domestic and industrial wastes without polluting the environment. This has sparked interest in using earthworms for large-scale waste disposal. Worms are thus seen as a biological resource for rural development. Maintaining the diversity of resources such as worms will help ensure a resource base for future technologies such as vermicomposting.

Vermicomposting

The practice of using earthworms for composting is known as vermicomposting. Not all earthworms are useful for vermicomposting. Earthworms are classified into two groups:

· Humus-formers (detritivores) - useful for vermicomposting

· Humus-feeders (geophagous) - useful for soil turnover and tillage. Worms used for vermicomposting should have following characteristics:

· Able to live in active compost.

· Tolerate extreme changes in temperature.

· Multiply fast, undergo rapid incubation, and mature quickly.

· Digest well and have such enzymes as cellulase and chitinase in their gut.

Aristotle described earthworms as "intestines" of the earth. Charles Darwin wrote about earthworms, "it may be doubted where there are many other animals which have played so important a part in the history of the world as have these lowly organized creatures."

Humus former

· Surface dwelling
· Red color
· Feed on nearly 90% fresh organic matter and 10% soil
· Harnessed for vermicomposting

Humus feeder

· Deep burrowing
· Pale color
· Feed on nearly 90% soil and 10% nearly degraded or humified organic matter
· Useful in making the soil porous and mixing and distributing humus through soil

Humus former and feeder

Species useful for vermicomposting are:

Exotic species	Indigenous species
Eisenia fetida	Lampitto mauritii
Eudrilus euginea	Perionyx excavatus
	Dravida vilsii
	Dichogester bolavii

Effects of vermicomposting on indigenous species

It is not possible to use both exotic and endemic humus-forming species for vermicomposting. Exotic species multiply very rapidly and outgrow the endemic species.

However, using humus-forming exotic species for vermicomposting can be useful. Fast turnover of organic matter by these humus-formers produces food rich in bacteria and humus for the indigenous humus-feeders. The humus-feeders can then multiply very fast under vermicompost heaps and after the compost is added to the field, stimulating their soil processing activities such as aeration, tunneling and soil turnover.

Vermicomposting for rural sanitation

Earthworms can be used to process human faeces. Vermiculture may be particularly useful for treating sewage in rural areas. Research has shown that some types of bacteria found in faeces, Serratia marcessens and Escherichia coli, are killed when they are ingested by the earthworm L. terrestris. The worms reduced numbers of the pathogen Salmonella erteriditis to a level of 2000-fold less, possibly because of competition from the endemic microflora of the worm gut.

Earthworms aerate sewage sludge and speed its drying, thereby favouring aerobic bacteria. Since most human enteric pathogens are anaerobes, sludge condtioning by earthworms can be beneficial from the public health standpoint. More research is needed on the effect of vermicomposting on other enteric bacteria, pathogenic viruses and parasites.

In villages in India, vermicomposting of latrine waste mixed with other agricultural waste can help dispose of sewage and produce valuable compost that can increase soil fertility and agricultural production.

Vermicomposting for rural sanitation

Vermicomposting of sewage sludge

· Aerobic sludge ingested by E. fetida is decomposed and stabilized about three times as fast as non-ingested sludge.

· Objectionable odors disappear more quickly.

· Marked reduction in populations of Salmonella enteriditis and other Enterobacteriaceae.

· Anaerobic sludge and sun-dried sludge is toxic to E. fetida.

· Sewage sludge can be, mixed with cellulosic and lignin-rich wastes.

· Earthworms, which accumulate heavy metals and agrochemicals from sewage, may be environmentally hazardous if used as protein source.

Practical applications of biodiversity

Symbiotic relationship between detritivorous worms and micro-organisms

Vermicomposting potential

· Population of India is 8,000,000.

· The average person produces an average of 1/2 kg of excrete every day.

· 4,000,000 kg of night soil, if vermicomposted, would yield 2,000,000 kg of humus-rich organic compost a day.

· Considering the night soil of the 70% of the population living in villages, nearly 1,400,000 kg vermicompost could be prepared every day.

Prepared by Dr. Jambbekar