Insects have both beneficial and detrimental economic impacts. They can damage crops and stored goods, transmit diseases, and sting or annoy humans. However, they also pollinate plants, decompose waste, and serve as a food source for other animals. Some insects even produce useful materials like honey, silk, shellac, and natural dyes. Overall, insects play an important role in ecosystems and the global cycles that sustain life.

1. ECONOMIC IMPORTANCE OF INSECTS
Dr. JeevanJyoti, PhD
Asst. Professor,
ACHS, Asmara
Chapter -1 contd…………

2.  The economic impact of insects is measured
not only by the market value of products they
produce but it includes the market value of
products they destroy and the cost of
damage they inflict but also by the money
and resources expended on prevention and
control of pest outbreaks. Although dollar
values for these losses are nearly impossible
to calculate, especially when they affect
human health and welfare.

3.  But despite the tremendous economic losses they
may cause, it is not entirely fair to cast the
members of Class Insecta as villains who rob us of
our food and livelihoods. They are also cherished
allies on whom we depend to keep the natural
environment clean and productive.
 They have shaped human cultures and
civilizations in countless ways, they supply unique
natural products, they regulate the population
densities of many potential pest species, they
dispose of our wastes, bury the dead, and recycle
organic nutrients. Indeed, we seldom stop to
consider what life would be like without insects and
how much we depend on them for our very

4.  Economic effect of insects
Advantageous effect Detrimental effect
direct
indirect

5. Insects represent an important food source for a wide
variety of other animal species. Freshwater fish such
as trout, bass and bream feed extensively on aquatic
insects like mayflies, stoneflies, or hellgrammites.
 Many toads, frogs, turtles, snakes, and lizards also
consume insects as a major part of their diet.
 Insectivory is common among land-dwelling birds.
 There are even some insectivorous mammals: shrews,
moles, bats, armadillos, and anteaters.
When other food is scarce, even foxes, racoons,
skunks, and bears will turn to insects as a source of
food.

6. 2. Insects as human food (entomophagy)
Insects are undoubtedly an important source of
nutrition today, they are still collected and eaten by
people of many cultures.
High in protein and low in fat, they may be fried or
ground into meal and mixed with flour to make tortillas.
Sago grubs, the larvae of a wood-boring beetle, are
considered a delicacy in Papua New Guinea.
Ants, bees, termites, caterpillars, water bugs, beetle
larvae, flies, crickets, katydids, cicadas, and dragonfly
nymphs are among a long list of edible insects that
provide nutrition for the people of Australia, Africa, South
America, Asia, Middle East, and Far East.

11.  Ants are eaten by many
of the tribes in the
Amazon.
 They are also used in
Sweden as a flavor to
gin.
 They provide protein,
thiamine, and riboflavin.
 Ant eggs are
commonly found in
the Mexico market.
 Honey pot ants are
served for desert.
 Leaf Cutter ants are
served toasted in movie
theatres in Columbia

12.  Bees are
consumed by
American, Indians.
 Commonly
consumed as a
bee brood.
 Chocolate covered bees
are a gourmet item in
Mexico.
 These item are also
canned for export.

13.  Usually placed in the
bottom of a bottle of
mesca.
 Many adult butterflies
and moths can be
eaten toasted or in
butter.
 They are most eaten
in caterpillar stage.

14.  Most commonly consumed
insect.
 Sold as a novelty dish in the
U.S.
 They can be roasted or
grounded into meat.
 They are also eaten as mush
or baked in dry cakes.
 Native Americans
dry and salt them.
 an excellent
source of protein.
 Native Americans
are known to take
them on trails. The
desert known as
“Desert Fruitcake.”

15.  Wasps have the
highest protein
content.
 Widely consumed
in Mexico.
 Many in Thailand
and Laos eat the
insect larva.
 Fried wasps, mixed
with boiled rice,
sugar, and soy sauce
was a favorite dish of
Japan Emperor
Hirohito.

16.  Since ancient times, honey bees (Apis mellifera) have been
valued for the honey and beeswax they produce.
 Honey is one of the beehive's principle food resources. It is
produced from droplets of flower nectar gathered by worker
bees. The nectar is temporarily held in the bee's foregut
where enzymatic action begins to convert sucrose into
dextrose (glucose) and levulose (fructose). In the hive, this
nectar-enzyme mixture is transferred to waxen cells, reduced
in volume by evaporation of water, and allowed to ripen into
honey. The bees seal each cell with a wax cap when the
process is complete. Worker bees make as many as 50,000
trips to and from the hive and visit up to 4 million blossoms in
order to produce a single kilogram of honey (2.2 lbs).

17. Wax is produced by epidermal wax glands on
the abdomens of worker bees; wax is a
constituent of the insect integument.
a soft, malleable material that bees use to build the
comb where honey is stored and larvae are reared.
The wax has a relatively low melting point so it is
easy to extract and purify with heat.
Beeswax is still used commercially in the
manufacture of cosmetics, candles, furniture
waxes, leather dressings, waxed paper, inks,
and medicinal ointments.

18. A silkworm, Bombyx mori, is the source of a unique
natural fiber used to make silk cloth. As each larva
spins its cocoon, it produces a continuous fiber of silk
that is about 0.075 mm (3/1000 inch) thick and 900 to
1500 m (3000-5000 ft) in length. This "domestic" silk
is highly valued for its light color and lustrous finish.
Silk is the strongest of all natural fibers. It is
comparable to steel or nylon in tensile strength, but
considerably more elastic. It can be dyed, spun into
thread or yarn, and woven into fabrics that are warm in
winter, cool in summer, resistant to wrinkling, and
exceptionally light in weight.

19. About 3,000 cocoons are required to make one pound
of silk.

20. Laccifer lacca, a tiny scale insect that grows on soapberry
and acacia trees in India and Burma, is the source of lac, a
sticky resin that forms the principle ingredient of commercial
shellac.
Twigs bearing the scale insects are heated to extract and
purify the resin. Up to 200 insects are needed for each
gram of lac (90,000 per pound).
Shellac, made by dissolving the lac in alcohol, was widely
used as a varnish (protective coating) for floors, furniture,
photographs, playing cards, and dried flower arrangements.
Alkali emulsions of shellac have been molded into electric
insulators, phonograph records, and dental plates. Lac is
the only commercial resin of animal origin.

21. 7.
8.
9. Bee Venom
Persons allergic to bee stings get desensitized by
injections, the allergin (venom) into blood stream.
it is also used in treatments of various diseases (rheumatic
diseases, arthritis, etc)
10. As anticoagulant and wound healer:
chitin, a component of cuticle can act as anticoagulant and
promotes wound healing.

22.  Substances from some
insects have been used in
medicines.
 Blow fly larvae has been used
to treat battle wounds.
 Blow fly larvae also is used as
treatment for bone infections.
 These larvae feed on dead
tissue and secrete a
substance know as allantoin
which is known to help
tissue heal.

23. 12. DYE
 Cochineal is a scarlet pigment extracted from Dactylopius
coccus, a scale insect that lives on prickly pear cacti in
Mexico and Central America.
 First used by Aztec Indians as a medicine, a textile dye, and
a body paint.
 Cochineal is very expensive because of its scarcity [150
insects are needed to produce one gram of dye (70,000 per
pound)], so it was used in only the finest fabrics. During the
American Revolution, British soldiers, known as "red coats",
wore uniforms dyed with cochineal.
 Today, the textile industry has largely replaced cochineal with
less expensive aniline dyes, but it is still used as a coloring
agent in foods, beverages, cosmetics (especially
lipsticks), and art products.

24.  As consumers, scavengers, and decomposers,
insects play a vital role in the biogeochemical cycling of
nutrients.
 Insects help aerate the soil, improve its retention of
rainwater, and enhance its tilth. They turn more soil
than earthworms and redistribute nutrients within the
root zone as they burrow and nest in the ground.
 Flies and dung beetles prevent the build-up of
manure from large animals waste and speed up its
decomposition by fungi and bacteria.
 Without such scavengers, the gradual accumulation of
waste products from large herds of cattle and other
ungulates (mammals with hooves) would soon render
much of the landscape unsuitable for agricultural
purposes.

25. - feed on pest species
- food for other animals
BENEFITS
12
14. Biological control: controls the population of
many other insects. Eg.- lady bird beetle
(coccinella) devours the mustard aphids at very
high rate.

26. •MOST OF US RECOGNIZE BEETLES AS
MAJOR PESTS!!
DID YOU KNOW THAT SOME PEOPLE
“TREASURE” THEM AS COLLECTIBLES??
15. As Collectibles

28. Direct effect:
1.Insects as cause and vectors of the diseases:
many diseases are spread by insect vectors eg-
malaria, dengu, filaria, yellow fever, kala-azar,
sleeping sickness, plague and typus fever etc.
- spread plant, human,
and animal diseases

29. 2. Venomous insects: bees, wasps inject venom
that may cause irritation on skin.
3. Blistering and urtication causing insects:
blister beetles contain toxic chemicals-
cantharidins when released causes blistering of
the skin. Moth caterpillars when come in contact of
skin cause skin irritation or urtication.
- sting us
(venomous)

30. 4. Insect allergenicity: stored products
infested with mites produce allergic
diseases (eg- baker’s itch).
5. Irritating insects: some insects do not
cause any injury but they cause irritation to
humans by their activites eg- ants,flies and
cockroaches.
- infest our homes
- infest our animals
and our bodies
-annoy us

31. 1.Crop pests: many insects have become pests to
many standing crops, eg- Pyrella of sugarcane, rice
bugs, locusts etc. these causes a great deal of damage
and thereby decrease the yield of food and vegetables,
as well as financial loss.
2.Loss of wooden building materials and furnitures:
termites with cellulase.
3.Damage of household goods: cockroaches and
crickets damage cotton cloth, woollen garments etc.
4.Damage of stored grains: beetles and weevils
damage the grains stored by the humans.

32. 5. Damage of books and literature: many
insects (silverfish) destroy books for their
cellulose feed.
6. Damage of railway tracks: termites damage
the wooden part of railway track that can lead
to accidents.
7. Damage to green trees: termites damage
the roots of trees under soil, some insect pass
fungal spores to trees leading to mycelial
infection resulting in drying of trees.
– eat our foods
- damage our crops

33. The common problems related to the vectors
are as follows:
1.Vector distribution: as they are
cosmopolitan, they transmit disease causing
agents where ever they go.
2.Vector abundance: mosquito vectors lay
around 100 eggs per batch in 2-3 days, egg
hatches and develop in 10 days. So there is
100-folds increase of adults. Higher number of
vectors also poses serious problems to human
for control.

34. 3. Survival ship of vectors: high rate of
survival. Females shows high fertility rate.
4. Anthropophilic nature: sanguivorous prefer
humans for their meal so they interfere with
human dwellings.
5. Feeding rate is very high: rate of damaging
things is also very high.
6. Resistance : they develop resistance to the
insecticides at a faster rate and pass this trait
to next generation also.