ECONOMIC IMPORTANCE OF

PHYLUM-ARTHROPODA....

1. Merostomata.....

• American species (Limulus polyphemus) sometimes fed to chickens & pigs

• Female specimens preferred on account of their eggs of which half-a-pint may be crowded into a cephalic shield

• It is believed that poultry will lay more eggs

Limulus polyphemus

•It fattens both fowls & pigs but also imparts a shocking flavor to their flesh •Asian species of horse-shoe crabs are consumed by humans

Eggs

American species Asian species

2. Arachnida.....

Scorpion studied in most of universities In tropical countries it enters housed becoming nuisance A poisonous animal, bite painful & sometimes fatal to children

They also are beneficial to some extent as feed on cockroaches & beetles

Scorpion venom used for pharmacological, biochemical & immunological researches

Chief centers in India are Haffkine Institute (Mumbai), School of Tropical Medicine (Kolkata) & Institute of Preventive Medicine (Hyderabad)

Scientists at these centers “milk” scorpions of their venom by giving them electric shocks while holding their stingers in glass pipettes

Certain mites cause damage to crop fruits like apple, pear, grapes (blister mite, Eriophyee) Ticks suck blood of man & animals by act as vector of protozoa causing Texas fever in cattle & tick fever in man

Blister mite

Ticks

3. Crustacea.....

Considerable economic importance to man Group is of great value directly or indirectly for human health & economic progress

a. As Food.....

Large numbers consumed by man Lobsters, shrimps, prawns, squillae, crabs, crayfishes Form an important diet of man with great nutritive value

Lobsters Shrimps Prawns

Squillae Crabs Crayfish

Most edible portions are tails as almost portion is composed of muscles Also some good meat in chelipedes In mud crabs claws are best part to eat Muscles cooked or canned

Blue crab (Callinectes) held captive until it molts, then sold in soft-shelled condition & after removal of the viscera the whole animal is cooked and eaten

Decapods & bivalve molluscs (shell-fish industry)

140 million $ marketed annually in USA alone

Prawn fishery very much advanced in several countries including India, giving employment to thousands

India earned more than 2000 million INR in 1955

Smaller species form bulk of zooplankton playing a vital role in food chains of both salt & freshwater fishes & aquatic animals Man eats fish & they feed on Daphnia & Cyclops Whales too depend on crustaceans for food

Daphnia

Cyclops

Amphipods & euphausids form greater part of diet of other animals (seals, sea gulls & penguins)

2 tons of Calanus (marine copepod, 5 mm) found in stomach of blue whale

Eggs of Artemia & Daphnia sold as fish food

Amphipods

Euphausids

Seals Sea gulls Penguins

Calanus Artemia Daphnia

b. As Fish Bait.....

In most parts of America, crayfishes quite popular among fisherman as fish bait Soft-shelled individuals kept soft for a week or on ice as refrigeration slows metabolism so that shell develops slowly

c. As Scavengers.....

Crayfishes are beneficial as they serve as an agency in the destruction of decaying vegetables & animal bodies in water

d. As Intermediate Host.....

Some crustaceans are parasites of aquatic animals

None is parasite of man & land animals

Handful of them serve as intermediate hosts to certain dangerous worms of man & other vertebrates

Dreaded human lung fluke (Paragonimus westermanii) uses a crayfish

Cyclops serve as intermediate host for human guineaworm (Dracunculus mediensis) & for broad tapeworm (Diphyllobothrium latum)

Guineaworn disease was once very common in India, Egypt & Central Africa Chandler & Reed (1961) recorded 48,000,000 human infections of guineaworm in 1947 Cyclops mainly responsible for such harm

e. As Pests.....

Certain crustaceans may become pests in large numbers

Crayfishes damage cultivated crops by eating young corn & cotton plants

Sow bugs & pill bugs also feed on vegetation, turn pests in green houses & fields when numerous

Crayfishes occasionally burrow, making holes in dams & weaken them causing serious damage Some crustaceans bore into marine timber structures (jetties, piles, poles, props) & destroy them causing loss of several millions

Some crustacean wood borers Chelura terebrans (Amphipoda) & species of Spheroma & Limnoria (Isopoda) They burrow into & damage wharves in salt water Barnacles form one of the fouling animals by attaching to hulls of ships

Chelura terebrans

Spheroma

Limnoria

Barnacles

4. Diplopoda.....

Millipedes may be useful as they are scavengers as dispose dead organic matter Cause damage to plants as feed on plant roots & destroy green houses & gardens

5. Chilopoda.....

Beneficial to man as they feed on insects

Some may be injurious also

Reported to feed on snakes too

Some harmless to man but some tropical ones inflict painful bite & cause fever, dizziness & headache

Scolopendra gigantea cause human death if victim is child

6. Insecta.....

Insects very well known for their economic value

A. Injurious Insects.....

a. Pests of plants, fruits & stored

grains......

Insects attack leaves, stems, buds, flowers, seeds, fruits, barks, woods, roots, vegetables, stored products, wool, feathers, cigars, tools & even minerals

Chewing insects (cabbage worm, hoppers & potato beetles) chew & swallow external parts of plants

Cabbage worm

Hopper

Potato beetle

Grasshoppers & locusts have invaded green crops so long Locusts move in swarms extending for many kilometers Grass & leaves devoured & even broken by weight of insects settling on them

Grasshoppers

Locusts

Plant bugs, aphids, scale insects possess extremely sharp-pointed proboscis, thrusted into the plant tissues for sucking of the plant juices

Plant bugs

Aphids

Scale insects

Bark beetles destroy timber in forests Boll weevils spoil cotton before harvest Caterpillars & Japanese beetles strip foliage from millions of shady trees every year

Bark beetles

Boll weevils

Caterpillars

Japanese beetles

b. Household Pests......

Several insects are unwanted guests in house

Mostly annoying, sometimes they become destructive

Bedbugs, mosquitoes & stable flies Ants, crickets, cockroaches, weevils, fruit flies, house flies & silverfish spoil food

Clothing, carpets, furs & feathers damaged by cloth moths & carpet beetles

Bedbug Mosquito Stable fly

Ant Cricket Cockroach

Weevil Fruit fly House fly

Silverfish Cloth moth Carpet beetle

c. Injurious to Domestic

Animals...... Domestic animals seriously injured by insects Many live more or less as parasites either externally (fleas, lice, bugs, mosquitoes) or internally (larvae of botfly in sheep)

Flea

Larvae of botfly

Lice

Bird lice (Mallophaga) feeds upon feathers of chicken, causing irritation & flesh loss Blood sucking horn fly serious pest of cattle Grubs of ox warble fly cut holes in skin of cattle causing damage of hide & flesh Larvae of horse bot fly cause serious disturbances in stomach

Bird lice Horn fly

Grubs ox warble fly

Larva horse bot fly

d. Disease Carriers......

Many insects play great role in spreading serious diseases in man & domestic animals

Often act as vectors for transmitting various disease producing organisms either by infecting them in blood stream (malaria) or by contaminating food (bacteria)

Various species of Anopheles convey parasitic Protozoa causing malaria Culex mosquito spread nematode worm (Filaria bancrofti) causing filariasis Yellow fever is spread by Stegomyia

Anopheles

Culex

Stegomyia

Surra disease among horses, camels of tropical countries by Tabanus African sleeping sickness by Tse-tse fly Typhoid, diarrhea, cholera by Musca domestica Bubonic plague by fleas Relapsing fever by bedbug & body louse Undoubtedly insects carrying diseases are greatest enemies of man, affecting human welfare most profoundly

Tabanus Tse-tse fly House fly

Flea Bedbug Body louse

e. Poisonous Insects......

Many insects & larvae produce poisonous secretions injected into the body of man & other animals either through bite or sting Honey bees, hornets, wasps, fire ants, bedbugs, mosquitoes & few lepidopterous & larvae

Honey bee Wasps Hornet

Fire ant Bedbug Mosquito

B. Productive Insects.....

Human beings are greatly indebted to certain insects which supply them with useful products Many commercial products produced by insects are indispensable to modern man

a. Honey......

Produced by honey bees (Apis) In USA 6 million colonies of honey bees produce 150,000 million tons of honey annually serving for human food & medicine

b. Beeswax......

Wax produced by honey bees used in polishes, churches, modelling & to wax thread Few scale insects also produce wax Scale insects

c. Raw silk......

Produced by silkworm (Bombyx mori & others) supply raw silk in Orient & Europe

1Cocoon= 1,000 feet fiber About 25,000 cocoons unwound for 1 pound silk thread

40 million kg silk produced every year globally

d. Lac......

Shellac of commerce obtained from waxy secretions of lac insect (Tachardia lacca) or scale insects (Coccidae) of India

Females secrete lac Useful as a foundation of lacquers & shellacs

e. Dyes......

Dyes (tannin, cochineal & crimson lake) derived from dried bodies of certain scale insects living on cacti Cochineal is no longer of value since synthetic aniline dyes have largely taken its place

f. Medical Products......

Certain medical products like Cantheridine derived from the blister beetles

C. Helpful Insects.....

a. Pollinators of Flowers......

„Insect friends‟ of man render him greatest service in pollination of flowers

plants depend upon certain insects for cross-pollination necessary for their fertility & vigor

Various insects & flowers mutually dependent as they depend on pollen & nectar

Bees, wasps, beetles, ants, flies

Bee Wasp Beetles

Ants Fly Butterfly

b. Scavengers......

Insects feed upon waste materials like dead bodies & debris of plants & animals so preventing decay & obnoxious odors Silver fish, blow fly, maggots, dung beetles, carrion beetles, fleas, cockroaches & many larvae

Silver fish Blow fly Maggots

Dung beetle Carrion beetle Cockroach

c. As Food......

Insects provide abundant food supply for animals like frogs, lizards, snakes, fishes Blue birds, meadow larks & house sparrows chiefly depend upon insects Moles, shrews, armadillos & ant-eaters live wholly upon small insects Man also consumes many insects & their larvae, eggs accidently with fruits & other fruits

Frog Lizard Snakes

Fish Blue bird Meadow

lark

House sparrow Moles Shrews

Armadillos

Spiny ant-eater

Scaly ant-eater

Natives of Amazon valley eat suab-ants

Termites form favorite food in tropics Eggs of Coriza femorata taken in Mexico

Goliath beetle of Africa are fine food morsel

Greek ground locusts in mortars & make flours

American Indians use to dry or smoke larger caterpillars & preserve them for later use

Ants Termites Coriza

femorata

Goliath beetle Locust Caterpillar

d. In Medicine......

Cochineal insects contain carminic acid, coccerin, myrestin, fat & fatty acids used in treatment of neuralgia & whooping cough

Blow fly larvae are used in treating decay of tissues

Cantheridin oil from blister beetles serves as hair restorer

Body extract of cocoons of Bombyx mori used in treating leucorrhoea & chronic diarrhea

Cochineal insects Blow fly larvae

Blister beetles Cocoons

Bee-venom used in treatment of some forms of arthritis & preparation of anti-venom to counteract snake bite Honey is a natural antiseptic preventing infection if applied to a wound Also used to cure ulcers Beeswax used as a base for ointment

Honey bee Bee-venom

Honey Beeswax

e. Biological Control......

Important service insects render to mankind is biological control over harmful species Insects attacking & eating other insects are predators Many harmful plant-eating insects devoured by predaceous insects (ground beetles, syrphid flies & wasps) Aphids & scale insects eaten by larvae & adults of ladybird beetles

Ground beetle

Syrphid fly Wasp

Aphids Scale insects

Ladybird beetle

Predaceous insects even reared or imported & liberated in orchards to control scale insects Predatory tiger beetles & nocturnal ground beetles beneficial as they destroy cutworms, armyworms, slugs & snails Larvae of parasitic insects attack larvae of plant-feeding insects (parasitoids) reducing their effectiveness

Tiger beetle Ground beetle

Cutworm

Armyworm Slug Snail

Parasitoids

f. Fine Arts......

Insects produce noises in various ways Sounds can be musical or disputable In Japan, cicadas & crickets are placed in in small cages like birds in houses In Tokyo about 50 markets were dealing with them prior to war Japanese celebrate an annual function “festival of singing insects”

Cicada Cricket

Beautifully colored elytra of some Coleoptera & Lepidoptera used in jewelry & pictures in Central America, in crafts by Indians of America, in pottery, baskets, metals, alloys by Red Indians of America & in ear-rings by Jivoras of Equador

Insects in jewelry

7. Onycophora.....

Forms a taxonomically important group Forms a link between Annelida & Arthropoda Otherwise of no economic importance

Peripatus

Thank You For Listening!!!!