A pest is any organism harmful to humans or human concerns. The term is particularly used for creatures that damage crops, livestock, and forestry or cause a nuisance to people, especially in their homes. Humans have modified the environment for their own purposes and are intolerant of other creatures occupying the same space when their activities impact adversely on human objectives. Thus, an elephant is unobjectionable in its natural habitat but a pest when it tramples crops. Some animals are disliked because they bite or sting; snakes, wasps, ants, bed bugs, fleas and ticks belong in this category. Others enter the home; these include houseflies, which land on and contaminate food, beetles, which tunnel into the woodwork, and other animals that scuttle about on the floor at night, like cockroaches, which are often associated with unsanitary conditions. Agricultural and horticultural crops are attacked by a wide variety of pests, the most important being insects, mites, nematodes and gastropod molluscs. The damage they do results both from the direct injury they cause to the plants and from the indirect consequences of the fungal, bacterial or viral infections they transmit. Plants have their own defences against these attacks but these may be overwhelmed, especially in habitats where the plants are already stressed, or where the pests have been accidentally introduced and may have no natural enemies. The pests affecting trees are predominantly insects, and many of these have also been introduced inadvertently and lack natural enemies, and some have transmitted novel fungal diseases with devastating results. Humans have traditionally performed pest control in agriculture and forestry by the use of pesticides; however, other methods exist such as mechanical control, and recently developed biological controls.Plants may be considered pests, for example, if they are invasive species or weeds. There is no universal definition of what makes a plant a pest. Some governments, such as that of Western Australia, permit their authorities to prescribe as a pest plant "any plant that, in the local government authority's opinion, is likely to adversely affect the environment of the district, the value of property in the district, or the health, comfort or convenience of the district's inhabitants."[12] An example of such a plant prescribed under this regulation is caltrop, Tribulus terrestris, which can cause poisoning in sheep and goats, but is mainly a nuisance around buildings, roadsides and recreation areas because of its uncomfortably sharp spiny burrs.Animals are considered pests or vermin when they injure people or damage crops, forestry, or buildings. Elephants are regarded as pests by the farmers whose crops they raid and trample. Mosquitoes and ticks are vectors that can transmit ailments but are also pests because of the distress caused by their bites. Grasshoppers are usually solitary herbivores of little economic importance. Many of the anima

1. Shri Shivaji Education Society, Amravati's
SHRI PUNDLIK MAHARAJ MAHAVIDYALAYA, NANDURA RLY.
DIST. BULDANA
Topic: Unit-V: Agriculture Zoology: Economic Importance of Insects
Class: B.Sc-III, Sem-V
Mr. Shantaram Bhoye
Assistant Professor & Head, Department of Zoology
M.Sc., NET-JRF, SET, M.A.(Eng.)

2. Agriculture Zoology: Economic Importance of Insects
 Beneficial Insects:
 Many different kinds of insects are found in and around our homes, gardens and fields.
 Most of these insects are completely harmless and may even provide valuable services for us.
 Usually, when we hear beneficial insects, we things like honey bees that produce honey, beeswax and more
importantly honey bees pollinate a wide range of fruit, vegetable, and field crops plus many flowers and
other ornamental plants.
 Lady beetles and praying mantis are predatory in nature as they feed on many insects pests and help in
reducing economic losses.

3. 1) Parasites:
 Parasites are usually the immature or larval stages of wasps and flies.
 The adult wasp or fly lay an egg in or on the egg or immature stage of the pest insects.
 The pest insects thus becomes the host for the developing parasite.
 Some adult parasites that lay their eggs in the host egg are so small that they are difficult to see without a
magnifying glass.
 Others may be as much as 1.5 inches long.
 A parasites larva usually feeds inside and slowly destroys the host.
 Parasites usually take longer time to become established than predators, but can severally limit the pest
population.

4. 2) Predators:
 Predators are usually larger than parasites.
 Both the adult and immature stages may be predators while only the immature stages of parasites attack pest
insects.
 Predators include a wide range of insects, mites and spiders.
 Predators actively seek and capture their prey.
 They either eat the whole prey or suck out the preys body contents.
 A single predators, whether an adult or immature, will kill and eat many preys during its life.
 In contrast, parasites kill only one host during their life.
 Predators may be generalists that kill and eat any insects they can capture or they may be specialists that feed
only on a few specific pest insects.
 Usually, the specialists are more valuable in controlling pest since that is all they feed on.
 Generalists also kill and feed on other beneficial insects.

5. Some common beneficial insects:
i) Spider:
 Spiders are not actually insects, they belong to the group of arthropods called Arachnids.
 There are many different kinds of spiders.
 Many of them spin a silk web that is commonly seen on various shrubs, trees, flowers, and even on the
grass.
 Spiders have six unique organs beneath their abdomen called spinnerets.
 Spinnertes allow the spiders to produce silk during their entire life cycle.
 Spiders have a special mouth part called chelicera with fangs.
 Most spiders are venomous but they are harmless to humans except few.
 Venom is used to paralyze the prey.
 They can be good general predators of pest insects.

6. Spiders are very beneficial in Garden and Farms:
 They eat many insects pests including aphids, caterpillars, cucumber beetles, flies, grasshoppers,
leafhoppers, plant bugs, and thrips.
 Spiders eat mosquitoes thus help to control malaria.
 The spiders silk has antibiotic property and hence is used in construction of nests by many birds.
 The spider silk can also be used as surgical threads, as they possess antibiotic property.
 Cloths woven from spider silk can protect us from ultra violet rays.
 Spider venom is used for making some insecticides.
 Spiders are used by many reptiles and birds as their food.
 Spiders help to keep balance in ecosystem.

7.  ii) Praying mantis:
 Praying mantis is a predator.
 It gets its name from its motionless raised front legs, which it uses to hold its prey.
 The color may vary from a light brown to green.
 Mantis have excellent eyesight and they will follow any movement, whether an insects or your finger.
 But they are not easy to locate, because their coloration and shape provide them with perfect camouflage
among the garden plants.
 The front legs are modified for grasping prey.
 Mantis feed on anything they can capture.
 The praying mantis completeness one life cycle per season.
 The female lays 1 to 5 egg cases on twigs and small branches.
 They enclose the eggs in a protective coating that resembles Styrofoam.
 The tiny nymphs emerges through the narrow slits of the egg case and immediately disperse into the foliage.
 They hatch out in the spring, completely the life cycle.
 Young nymphs are very aggressive towards each other.
 They are pugnacious, i.e. larger forms attach smaller forms and female eat males after nuptial.
 In 5 or 6 months, they become a full sized adult (up to 6 inches).

8. Praying mantis are beneficial as they control many pest:
 Praying mantis is ferocious general predators.
 They feed on many pest insects, other mantis, and also on other beneficial insects.
 Praying mantis can handle even the largest pest in the garden.
 Even, when the nymphs hatch, they are so hungry they sometimes eat their siblings.

9. iii) Ladybugs:
 Ladybugs, also called lady beetles or ladybird beetles.
 An adult ladybug has a very characteristic convex, hemispherical to
oval body shape.
 They may be white, yellow, pink, orange, red or black, and usually
have spots.
 A few feed on plant and pollen.
 Lady beetles, both adults and larvae are known primarily as predators
of aphids (plant lice), but they prey also on many other pest.
 One larva will eat about 400 medium-size aphids during its
development to the pupal stage.
 An adult will eat about 300 medium size aphids before it lays eggs.
 More than 5000 aphids may be eaten by a single adult in its lifetime.

10. Lady beetles are very beneficial:
 They are natural enemies of many insects, especially aphids and other sap feeders.
 Ladybugs are voracious predators of harmful pests, but they also eat other small, soft bodied insect
larvae, insect eggs, including scales, mealy bugs, leaf hoppers, mites.
 They are capable of consuming up to 50 to 60 aphids per day.
 The female ladybug deposits her eggs in small yellow clusters under a plants leaf or on the stem.
 The lady beetles huge appetite and reproductive capacity often allow it to rapidly clean out its prey.
 Within 7 days the tiny eggs hatch into alligator shaped larvae.
 They quickly begin feeding on many soft bodied pests, mites, and insect eggs.
 Within a month the larvae pupate and one week later young adults emerge and get ready to feed.

11. iv) Damsel bug (Nabis sp):
 Damsel bugs are a true bug from true order Hemiptera.
 Adult damsel bugs are between 0.3 and 0.5 inches long with bodies that
taper towards the narrow head.
 When they feed on bugs, they insert their needle-like mouthparts into
their prey and suck out the juices leaving a dry shell.
 Immatures feed on small, soft bodied insects like aphids while the adults
capture larger prey like caterpillars.

12.  Damsel bugs are generalist predators, meaning that they feed on almost any insect.
 Eggs are inserted into plant tissue by females.
 Nymphs hatching from eggs develop through five stages (instars) in about 50 days.
 The nymphs stages of damsel bugs feed on smaller prey including mites, aphids, and eggs.
 Adult damsel bugs feed on both large and small prey including spider mites caterpillars,
potato beetles, cabbage worms, corn earworms, and leafhoppers.
 Damsel bugs can live up to two weeks without feeding on prey, but if left longer without
food they will start eating each other.
 They tend to eat pest insects, but also eat other beneficial insects, including big-eyed bugs
and minute pirate bugs.

13.  V) Mealy bug destroyer:
 It is small (1/5 inch long), reddish-brown lady beetle with
dark-brown wing covers.
 Both the adult and larval stages of this beneficial insect attack
and feed on all stages of mealy bugs. It also eats aphids and
soft scales.
 Adult female predators lay yellow eggs among the cottony egg
sacks of mealy bugs. Eggs hatch into larvae in about 5 days.
 The three larval stages last from 12-17 days.
 The larvae feed on eggs, young crawlers, and the sugary liquid
excrement, often called honeydew.
 Pupation occurs on sheltered plant stems or on greenhouse
structures.

14.  vi) Soldier Beetles:
 Adult soldier beetles are long and narrow, red, orange or
yellow head and abdomen and black, grey or brown soft wing
covers.
 Larvae are dark, elongated and flattened.
 Both adults and larvae are beneficial.
 Adults feed on aphids, pollen or nectar on flowering shrubs.
 Larvae feed primarily on eggs and larvae of beetles,
butterflies, moths and other insects.

15. vii) Green lacewings:
 Most of the beautiful adult lacewings are easily identified by their delicate, netted wings, which they
hold roof like over their body while at rest.
 There are two kinds of lacewings, green and brown feed on pollen, nectar, and honeydew.
 The adult lacewings lays her eggs on the foliage, each on top of hair like, filaments.
 She may lay them singly or in clusters.
 The eggs hatch and tiny larvae emerges.
 The immature lacewings resemble lady beetle larvae.
 Five days later the adult emerges to complete the life cycle.
 The common green lacewing is a widely used beneficial insect.
 It naturally controls many different pests.
 Green lacewing larvae are voracious predators.

16.  Lacewing larvae vigorously attacks its prey, injecting a paralyzing venom.
 Larvae hunt for soft bodied prey, using their curved, pointed mandibles to stab their
victims.
 A single lacewing larva can eat 25 to 30 aphids each day. It is known as the “aphid lion”
because of its voracious appetite.
 They feed on aphids, citrus mealy bugs, cottony cushion scale, spider mites, thrips,
caterpillars, insect eggs, etc.

17.  viii) Syrphid fly (Hover fly):
 The adult syrphid fly is a large, 13mm long, and beautiful insect.
 The flies often wear bright markings of yellow-orange and black,
and can be mistaken for bees.
 The female lays its white eggs singly, close to the developing
aphid colony.
 The eggs hatch within two to three days.
 The larva is a legless, slug-take maggot which later develops into
adult.
 The larvae of syrphid fly form natural control of many pests.
 Syrphid maggots crawl on garden foliage, searching for aphids to
eat.
 They are quite good at squeezing in the curled up leaves where
aphids hide, too.
 As an added bonus, the adults will pollinate the flowers.
 Syrphid flies are also called hover flies, because they tend to
hover flowers.

18.  ix) Tachinid Flies:
 The Tachinidae are a large and variable family of true flies within the
insect order Diptera, with more than 8,200 known species and many
more to be discovered.
 Tachinid flies are extremely varied in appearance.
 These are similar in shape and size to houseflies.
 They have three-segmented antennae, a diagnostically prominent post-
scutellum bulging beneath the scutellum.
 They glue their eggs to their host or lay their eggs on foliage or inject
their eggs directly into the unsuspecting host body.
 They help control garden pests such as gypsy moths, cabbage loopers,
Japanese beetles, armyworms , cutworms, sawflies, codling moths,
peach twig borers, pink bollworms, tent caterpillars, squash bugs and
many more.
 Adult flies feed on flowers and nectar from aphids and scale insects.
 As many species typically feed on pollen, they can be important
pollinators of some plants, especially at higher elevation in mountains
where bees are relatively few.

19. x) Ichneumon wasp:
 The Ichneumon wasps are insects classified in the Hymenoptera
and suborder Apocrita, family Ichneumonidae.
 They are solitary insects, and most are parasitoids, the larvae
feed on or in another insect which finally dies.
 Being in the same order, ichneumons are closely related to other
hymenopterans, such as ants and bees.
 Ichneumon wasp species are highly diverse, ranging from 3 to
130 mm long.
 Most are slender, with the females of many species in the genus
Megarhyssa having an extremely long ovipositors for laying
eggs.
 Upon hatching, the larval ichneumon feeds either externally or
internally, killing the host when it is ready to pupae.

20.  The ichneumon is parasitic, as its larva develops on other insect pests.
 The females deposit their eggs in the body of host e.g., Caterpillars (Lepidoptera).
 The tiny larvae that hatch fed upon the fatty tissues of the caterpillars body without damaging any
vital organs.
 When the Ichneumon larvae are almost full grown they begin to feed on the more vital organs,
resulting in death of the caterpillar.
 In may cases the caterpillar continues to live, and it is only after the Ichneumon larvae enters the
pupa stage and attacks the vital organs, till the Caterpillar die.
 Thus various ichneumons are used successfully as biological control agents in controlling pests such
as flies or beetles or butterfly or moth.

21.  xi) Trichogramma wasp:
 Trichogramma are minute polyphagous wasps, commonly known as
stingless wasps, that are endoparasitoids of insect eggs.
 Endoparasitoids lay their eggs in eggs or larvae of other species.
 Members of the Trichogrammatidae family range in size from 0.2 to
1.5 mm.
 They are black, brown, or yellow in color.
 The wings are margined with hairs.
 The greatest width of the body is at its eyes.
 Trichogramma minutum is one of the most commonly found species
in Europe and was first mass reared in 1926 on eggs of Sitotrogace
realella.

22.  These tiny wasps are parasites inside eggs of other insects. The entire immature life is spent within the
host egg.
 Female adults use chemical and visual signals, such eggs shape and colour, to locate eggs within a crop.
 When a suitable egg is found the female uses antennal drumming to determine the size and suitability of
the egg.
 Depending on the size and quality of the target egg, the female drills a hole into the chorion and inert an
appropriate number of eggs.
 A single female can parasitize one to ten eggs a day.
 They lay one to fifty eggs in single host egg, which then terminates development. The host eggs turn
black. The larvae feed on the egg and emerged as an adult. Female normally outnumber males depending
on the availability of food.
 Some species actually swims underwater in order to place their eggs in those of aquatic insects. The
adults feed on the nectar from the flowers of weeds and flowers of the daisy and carrot families.
 They parasitize eggs on up to 200 insects pest, including the eggs of Aphids, Army cutworm, Cabbage
looper, Cotton square Borer, Green fruit worm, Greenhouse whitefly, Gypsy moth, Imported cabbage
worm, Mealybugs, Oblique banded leafroller, Orange dog, Oriental fruit moth, Scale insects, Tomato
hornworm and various Beetle larvae.

23. Harmful insects:
 A) Stored Food Grain Pest:
 It has been estimated that between one quarter and one third of the world grain crop is lost each
year during storage.
 Much of this is due to insect attack.
 In addition, grain which is not lost is severally reduced in quality by insect damage.
 Many grain pests preferentially eat out grain embryos, thereby reducing the protein content of
feed grain and lowering the percentage of seeds which germinate.
 Some important stored grain pests include the rice weevil, meal worm, khapra beetle, and rust
red flour beetle.

24. 1. The Rice Weevil (Sitophilus oryzae):
Occurrence: Throughout India, Cosmopolitan.
Identification:
 The adult is a small beetle about 1/6 – 1/8 of an inch in length and reddish brown, dark brown or almost
black in colour, with the head having shape of a long slender snout.
 The wings have four light reddish or yellowish spots and the insects is able to fly.
 The grubs are small, white and legless, with yellowish brown head.
 They are always found inside the kernels of grain.
Host Complex:
 In India it is commonly found in the stored cereals such as rice, wheat and millers like maize, jowar,
barley, bajra, etc.
Injuries:
 Adults and grubs feed on grains leaving behind only skin of the grains.
 Both adults and larvae feed voraciously on grains so much so that the time grain becomes unfit not only
for consumption but also for seed purpose.
 Adults live in the cracks and crevices of the godowns during winter.

25. Control:
i) Primary measures:
 Sun drying of the storing grains.
 The broken grains must be separated.
 Godowns should be clean, damp-proof and with heating arrangement.
 Before storing the grains, godowns to be heated to 150°F at least for 10-12 hours.
 Grains can be mixed with dry neem leaves.
ii) Chemical measures:
 Grains to be mixed with 5% BHC at the rate of 0.15% by weight of the grains earmarked for seeds or
to be dusted with 5% BHC if grains are to be used for human consumption.
 Empty godowns should be sprayed with 4% BHC or 0.02% malathion before storage.
iii) Fumigation:
 Fumigation of grains by HCN for 18hrs in the closed godowns.
 Other fumigants included-ethylene dibromide, methyl bromide, Kiiloptera (EDCT mixture) and
Phostoxin tablets.

26. 2. The Red Flour Beetle-(Tribolium castaneum):
Occurrence: Throughout India, cosmopolitan.
Identification:
 It is 4 mm in length and reddish brown in colour.
 Head and dorsal side of the thorax are densely covered with minute punctures.
 The last few segments of antennae are much larger in size than the preceding ones.
 Host complex: common to powered products granaries in India.
Injuries:
 Adult and larva which feed mainly on the germ of the cereal.
 It feeds on powdered products produced by other pests after feeding the grains or the broken grain
specially rice, miller products like atta, Maida and Suji.
 In case of heavy infestation, flour turns grayish yellow and subsequently become moldy and emits a
pungent smell, acquiring an unpalatable and objectionable taste.
 This pest is particularly abundant in flour mills.
 The pest becomes serious in humid season.
 It also damages beans, peas, baking powder, ginger, dried fruits, insect collection, nuts, chocolate, etc.

27.  Control:
 i) Primary measures:
 Sun-drying of the storing grains.
 Godowns should be clean, damp-proof and with heating arrangement.
 Before storing the grains, godowns to be heated to 150°F at least for 10-12 hours.
 grains can be mixed with dry neem leaves.
 ii) Chemical measures:
 Grains to be mixed with 5% BHC at the rate of 0.15% by weight of the grains-earmarked for seeds or to
be dusted with 5% BHC if grains are to be used for human consumption.
 Empty godowns should be sprayed with 4% BHC or 0.02% malathion before storage.
 iii) fumigation:
 Fumigation of grains by HCN for 18 hrs. in the closed godowns.
 Other fumigants includes-ethylene dibromide, methyl bromide, Kiiloptea (EDCT mixture) and
Phostoxin tablets.

28. 3. The Khapra Beetle (Trogoderma granarium):
Occurrence: Throughout India, Cosmopolitan.
Identification:
 The adult beetle is brownish black, oval and about 3-4mm long, convex.
 The body is covered with very fine hairs.
 Males are smaller than female.
 The larva is yellow brown with yellow intersegmental rings, covered with long brown hairs, and when
mature is about 6-7mm long.
Host Complex: Common in stored wheat grain.
Injuries:
 The Khapra beetle is a primary pest of stored grain particularly wheat, rice, corn, millets, barley,
pulses, dried fruits, nuts, dried milk, fresh meal, etc.
 Only the larvae feed on grains right from superficial layer to the internal embryo and the grains
become useless for germination.
 The larvae are able to develop in food with a moisture content as low as 2% and are able to tolerate
temperature up to 44°C.

29. Control:
i) Primary measures:
 Sun drying of the storing grains.
 Godowns should be clean, damp-proof and with heating arrangement.
 Before storing the grains, godowns to be heated to 150°F at least for 10-12 hours.
 Grains can be mixed with dry neem leaves.
ii) Chemical measures:
 Grains to be mixed with 5% BHC at the rate of 0.15% by weight of the grains earmarked for seeds
or to be dusted with 5% BHC if grains are to be used for human consumption.
 Empty godowns should be sprayed with 4% BHC or 0.02% malathion before storage.
iii) Fumigation:
 Fumigation of grains by HCN for 18 hrs. in the closed godowns.
 Other fumigants includes-ethylene dibromide, methyl bromide, Kiiloptera (EDCT mixture) and
Phostoxin tablets.

30. 4. The Angoumois Grains Moth (Sitotrog acerealella):
Occurrence: Throughout India, Cosmopolitan. Severe attack occurs during rainy season.
Identification:
 The adult moth is small, 8-10 mm in length, with narrow wings fringed with hairs.
 The head is characterized by yellow brown colour.
 While sitting the wings are completely folded over back in a sloping manner.
 The wing span is 10-14 mm.
Host complex:
 Serious pest of stored cereals (wheat), millets like maize, sorghum etc.
Injuries:
 Caterpillars bore the cereal grains.
 The infested grains are hollowed out and filled by excreta and webbing by the larvae.
 Grains become unfit for consumption.

31. Control:
i) Primary measures:
 Sun-drying of the storing grains.
 Godowns should be clean, damp-proof and with heating arrangement .
 Before storing the grains, godowns to be heated to 150°F at least for 10-12 hours.
 Grains can be mixed with dry neem leaves.
ii) Chemical measures:
 Grains to be mixed with 5% BHC at the rate of 0.15% by weight of the grains earmarked for seeds or
to be dusted with 5% BHC if grains are to be used for human consumption.
 Empty godowns should be sprayed with 4% BHC or 0.02% malathion before storage.
iii) Fumigation:
 Fumigation of grains by HCN for 18 hrs. in the closed godowns.
 Other fumigants includes-ethylene dibromide, methyl bromide, Kiiloptera (EDCT mixture) and
Phostoxin tablets.

32. 5. The pulse beetle (Callosobruchus chinensis):
Occurrence: Native of China but distributed in India, Myanmar, Japan, Africa, USA, Philipines, etc.
Host Complex: Serious pest of stored pulses like chickpea. Pea, lentil, beans, etc.
Identification:
 Adult beetle is reddish brown, measuring 3-4 mm in length having long serrated antennae.
 There is only one generation per year.
Injuries:
 It is a major pest of pulses particularly chickpea, Pea, lentil, beans, etc.
 The grubs eat up the interior of the grain leaving the outer shell of the grain and make them useless
for human use.
 It can thrive, on milled whole pulse with husk factor, while it does not grow on processed pulse
products.
 The beetle also infest the grains in field.
 The adults do not feed on stored products at all.

33. Control:
i) Primary measures:
 Sun drying of the storing grains.
 The broken grains must be separated.
 Godowns should be clean, damp-proof and with heating arrangement.
 Before storing the grains, godowns to be heated to 150°F at least for 10-12 hrs.
 Grains can be mixed with dry neem leaves.
ii) Chemical measures:
 Grains to be mixed with 5% BHC at the rate of 0.15% by weight of the grains-earmarked for seeds or
to be dusted with 5% BHC if grains are to be used for human consumption.
 Empty godowns should be sprayed with 4% BHC or 0..02% malathion before storage.
iii) Fumigation:
 Fumigation of grains by HCN for 18 hrs. in the closed godowns.
 Other fumigants include-ethylene diabromide, methyl bromide, Kiiloptera (EDCT mixture) and
Phostoxin tablets.

34. 6. The Almond Moth (Cadra cautella):
Occurrence: Cosmopolitan.
Host Complex: Commonly in flour mills.
Injuries: Caterpillars feed on food stuff, grains, flour. They form massive webs and clogging making grains,
flour useless for human use.
Control:
i) Primary measures:
 Sun drying of the storing grains.
 Godowns should be clean, damp-proof and with heating arrangement.
 Before storing the grains, godowns to be heated to 150°F at least for 10-12 hours grains can be mixed with
dry neem leaves.
ii) Chemical measures:
 Grains to be mixed with 5% BHC at the rate of 0.15% by weight of the grains earmarked for seeds or to be
dusted with 5% BHC if grains are to be used for human consumption.
 Empty godowns should be sprayed with 4% BHC or 0.02% malathion before storage.
iii) Fumigation:
 Fumigation of grains by HCN for 18 hrs in the closed godowns.
 Other fumigants includes-ethylene dibromide, methyl bromide, Kiiloptera (EDCT mixture) and Phostoxin
tablets.

36. Pest of economically important crops:
 Pest:
 Harmful insects for crop plants are known as pest.
 They cause a huge economic loss to farmers every season and their control measures involve a great
manpower and money.
 A) Pests of Cotton:
 Cotton being the major cash crop of our region, insects attacking cotton crop are of great
importance.
 For controlling the damage done by these insect it is necessary to know their identification and
control measures.
 The three important pests of cotton are spotted boll worm, Pink boll worm and Red cotton bug.

37. 1. Spotted Bollworm (Earias vitelli, Earias insulate):
Host Plants: Cotton, Maize, Lady’s finger, Hibiscus.
Identification:
 E. vitelli is a small moth measuring about 12 mm in length and 25 mm in wing span.
 Fore wings have a board green band which give it a banded appearance.
 The fore-wings of E. insulana are of greenish colour and hind wings of both the species are white.
 The body colour is bright green and abdomen is silvery white.
Damage:
 The infective stage is caterpillar.
 The caterpillar bore the stem of young seedlings and feed upon the buds, flowers and then bore the bolls
causing their heavy dropping.
 The infested shoot wither, dropped and die.
 A number of holes are formed on the infested bolls plugged with excreta.
 One caterpillar can destroy many bolls in its life span of one month.
 The infested bolls premature and produce poor lint which fetches 50-80% lower price.

38. Control Measures:
i) Primary Measures:
 During June-July the attacked shoots and bolls should be collected along with alternative host
plants and destroyed or burned.
ii) Chemical Control Measures:
 Spray of Carbaryl 0.1% at 15 days interval during August-September, suppresses the pest
population.
 Dusting of 5% fenitrothion at the rate of 25kg per hectare is also effective.

39. 2. Pink Bollworm (Pectinophora gossypiella):
Identification:
 It is small grey, dark brown moth measuring 1 cm long and wing span 1.5 cm.
 Fore wings provided with blackish and hind wings are deeply fringed.
 The antennae are filiform and they are nocturnal in habit.
Damage:
 Caterpillar is the infective stage, which bores flower buds, flowers and bolls of cotton.
 They feed on seeds internally and seal the holes after entering the bolls.
 The attacked seed cotton gives a poor ginning percentage, less oil extraction and poor spinning quality
of cotton.
 Moreover within cotton, seeds they may undergo diapause and are transported from place to palace
unidentified.

40. Control measures:
i) Primary measures:
 The seeds should be kept under ‘Sun heat Treatment’ before sowing.
 The fallen leaves, bolls, cotton sticks should be collected and destroyed.
 Ploughing and irrigation will destroy hibernating caterpillars.
ii) Chemical measures:
 Cotton seeds fumigated by carbon di-sulphide or methyl bromide at 5cc of fumigant per 100kg of seeds.
 Seed heating at 60°C by Simon Cotton Seed Heater or Sun Heating.
 Spraying with 0.2% Carbaryl, 0.05% endosulphan 4-5 times after 15 days during August-September.
iii) Biological control:
 Natural enemies like larval parasites e.g., Mites, Microbracongreeni, Microbraconlefroyi may be
introduced.

41. 3. Red Cotton Bug (Dysdercus cingulatus):
Identification:
 The red cotton bug is blood red pest.
 Females (15 mm) are longer than males (12 mm).
 Fore wings, antennae and scutellum are black.
 Ventral side of abdomen i.e. stomach with many transverse white bands.
 Mouth parts are piercing and sucking type.
 They form a straight beak or rostrum.
Damage:
 The nymph and adult suck the plant sap from the leaves, shoots and bolls.
 The lint is stained red.
 They badly affect the quality of ginning and oil content.
 If the attack is severe, boll open badly and the lint is of poor quality.
 The seed of infested cotton have low percentage of germination.

42. Control:
i) Primary Measures:
 Mass killing of the nymphs and adults by hand picking and putting in kerosenised water.
 Ploughing the field to expose the egg to sun light.
 The crop of bhindi should be sown as trap crop and pests collected should be destroyed.
ii) Chemical Measures:
 Spraying of malathion 0.05% is effective.
 Spraying of 1 liter endosuphan 35% and methyl parathion is useful to control the pest.
iii) Biological Measures:
 Predators like Antilochus coquiberti and Harpactor costalisare commonly used.

43. B) Pest of Sugarcane:
1. Pyrilla purpusilla (Leaf hopper):
 Identification: Adult Pyrila is straw coloured and is very
active.
 Head with a long beak like proboscis and prominent red eyes.
 It measures about 20 mm long.
 A pair of whitish brown anal processes, covered with white
mealy wax, are also found which help in up and downward
active movement of the insects.
 Two pairs of wings are folded like a roof.

44. Damage:
 Both nymph and adult bugs suck plant sap from leaves causing drying and shedding of leaves.
 The insects discharges honey dew on leaves on which the black fungus grows so that the leaves
become black and photosynthesis is prevented.
 Cane losses percentage of sucrose, about 50% during severe attack.

45. Control measures:
Primary measures:
 Collection of egg masses and destruction.
 Disposal of cane trash.
 Bagging of adults in nests.
 Striping of dried leaves, leaf-sheath at large scale.
Chemical Measures:
 Spraying of dimecron, dimethoate, metasystox or carbaryl.
Biological measures:
 Egg parasites: Tetrastychu spyrillae, Cheiloneuru spyrilae.
 Egg predators: Coccinellase, Chiomenes sexmaculata.
 Nymph parasite: Caterpillars of Epipyro psemlanoleuca
 Nymph Fungi: Metarrhiziu manisopliae.

46. C) Pest of Jowar:
1. Jowar stem borer (Chilo partellus):
Identification:
 The adult moths are straw coloured with yellowish
grey forewings bearing fine dots on apical margin.
 The hind wings are whitish and fringed.
 Females are longer than males.
Damage:
 It generally attacks older plants.
 The first instar and later larvae are internal feeder
which leads to death of the central shoot and
formation of “dead hearts” without showing any
external signs.
 The damage done by them is about 80% in case of
severe infection.

47. Control measures:
Primary measures:
 Removal and destruction of “dead hearts”. Burning of stubbles and trash which became a source of
next infection.
 Collection and destruction of caterpillars.
 Collection and destruction of adults by light or pheromone traps.
 Sowing of resistant varieties.
Chemical measures:
 No insecticide treatment is effective as larvae and pupae develop inside the stem.
Biological measures:
 Introduction of Trichograma, Telenemus as egg parasites and Apantele scolemany, as the larval
parasites is common.

48. 2. Jowar midge fly (Contarinia sorghicola):
Identification:
 Jowar midge fly is slender mosquito like bright red or pinkish.
 It has bright orange abdomen and a pair of transparent wings.
 Wings cover the whole abdomen.
 Female bear a long slender ovipositor.
 Adults are short lived.
 Males live for few hours and females upto 24-48 hours.

49. Damage:
 Larvae feed on ovaries and inhibits formation of grains.
 In November they occur in large population infesting severely the 3-7 day old ear heads or litters,
causing 20-50% loss of crop.
Control measures:
Primary measures:
 Mass collection of adults by light trap.
 Removal of infested ear heads, panicle.
 Rejection of early varieties for sowing.
Chemical measures:
 2,3 spraying or dusting with malathion (30% EC) in 500 liter of carbaryl (50%) or endosulphan
(35%) in one liter or water per hector of crop.
Biological measure:
 Introduction of larval and pupal parasites like Tetrastichus and Eupelmus, etc.
 Ant Tapinoma inducum is also an effective predator.

50. Economic importance of Rodents:
 Rats have been cause of severe damage to crops, fruits, trees, vegetables and in the
field and almost every food grain in houses and godowns.
 Around 110 species of rats, from India, are damaging the crops.
 They are very active, cunning and prolific breeders so their population is increasing
day by day.
 The nature of damage by the rats is variable from species to species and crop.
 They first attack on cereals to dicot seeds and grain.
 In wheat crop the maximum damage was recorded at the ripening stage.
 The damage of sugarcane crop due to rats in field is much least in early stages but in
later stages i.e., from October on wards, sugarcanes are attacked much more by rats.
 In coconut fruits one or two holes are made by the rats near the stack and they damage
the carpal of the coconut.

51.  Rats feed actively in 5-10 meters radius around their borrows.
 The amount of damage caused is proportionate to the population of rats in that area.
 From the data available rats destroy 11.5% wheat, 5.8% barley and 0.9% gram in the field.
 They destroy 4.6%-5.4% paddy, 4.1% - 25.8% ground nut, 1.4% maize, 2.2% sugarcane and 5%
coconut.
 The burrows of rats weaken the foundation of buildings, cause seepage in channels, damage railway
tracks in yards, etc.
 They cause fire by damaging the electric wires.
 The damage to the food material and other materials due to rats is around 15 million.
 Rats also are responsible for spreading the disease among human brings and their pets.
 Around thirty two diseases are known to be transmitted by rats.
 They are carry nearly 18 different kinds of lice, fleas, ticks and mites.
 They carry many types of viruses, bacteria, fungi, protozoa, nematodes and cause several diseases like
bubonic plague, typhus fever, infectious jaundice, rat bite fever and food poisoning.

52.  These diseases are transmitted through contact with rodent urine, dropping or nesting materials that
stirred up, releasing the virus into the air.
 This is known as airborne transmission.
 But it can also be transmitted through getting bite by the rodent, or touching an object contaminated
with rodent feces/urine or saliva and then afterwards touching your mouth or nose.
Control:
Biological Control:
 Introducing predators to farm is a far superior form of rodent control opposed to conventional methods
such as trapping and the use of poisons.
 Rodents learn to avoid traps and poisons compromises the quality of eco-systems and the population of
desirable animals.

53.  The majority of snakes are non-venomous and harmless animals.
 Some of the venomous snakes of India are-Cobra, King cobra, krait, pit viper, Indian viper, rattle snake, coral
snakes, sea snakes, etc.
 Snakes are absolutely paramount to the health of many ecosystem, the environment and to biodiversity.
 They are extremely valuable components to the ecological communities in which they live, playing several
complex roles, including that of predators and prey.
 The natural predatory behaviors of snakes are also extremely valuable to humans.
 Many snake species prey heavily on insects and rodents.
 When snake populations decline the populations of these prey items increases, often causing serious
problems to people.
 Insects and other arthropods can destroy gardens or enter human inhabitation where they are undesired.
 When rodent population serge, the animals can destroy crops at an alarming rate, effecting supplies of food
and industries.
 They can also spread many harmful diseases.
 It is well documented that rodents are also a leading cause of house fires, caused by the chewing of electric
wires.
Economic importance of snakes:

54.  Snakes are very effective at hunting such prey because they
can crawl into small burrows and other areas that rodents use
as shelters.
 Snakes are also helping to save the lives of millions of people
every year, as the venoms from snakes are being used to treat
many serious health elements like cancers, heart stroke,
Parkinson disease and many more.
Disadvantage:
 The main disadvantage of having snakes in your garden and
farms is that they will bite if you accidently disturb them and
they don’t have an easy exit.
 While many of these snakes are not venomous, the
rattlesnakes bite can be fatel without swift medical
intervention.
 Snakes also don’t distinguish between bad insects and
beneficial bugs. They all eat whatever is available.

55. Economic importance of owls:
 There are many species of owl.
 They are nocturnal but are frequently seen during day time also.
 By maintaining constant check on rodents and other destructive vermin they are of great economic value
to agriculture and deserve the strictest protection.
 Barn owls are farmers best defense against rodent infestation.
 A barn owls diets consists mainly of small rodents such as mice and rats.
 Installing barn owl boxes around home, farm, vineyard, garden is the perfect natural rodents control
method.
 A single pair of barn owl can consume up to 2000 rodents a year.
 When feeding babies that number drastically increases.
 A pair with 6 babies can consume 1000 rodent in the offsprings first 3 months of nesting.
 Thus, owls can have various roles in an ecosystem, depending on the environment.

56.  For example, in a woodland environment, the
owl population restricts the population of
mice, rats, and other small animals that it
might eta, preventing overpopulation.
 Also, owls feces adds to the soil in the forest,
allowing plants to grow.
 Overall, owls, like all organisms, are
essential to ecosystems in various ways.

57. Some bats help control the insect population:
 Worldwide, bats are the major predators of night-
flying insects, including mosquitoes and many
crop pests.
 An individual Mouse-eared Bat from North
American can catch up to 600 mosquitoes in an
hour.
 It has been estimated that the colony of 300,000
bats catch 100 tons of insects a year, including
many crop pests, thus providing an important
services to farmers. Thus bats play a giant role in
agriculture.
 They account for approximately a quarter of all
mammals-a massive army that operates as the
scourge of the insect world.
 With bats eating all those insects, this means
fewer chemicals and poisons will be used on
crops, and that’s healthier for all of us and the
ecosystem.
Economic importance of Bats:

58. Many bats spread seeds for new plants and trees:
 Throughout the tropics the seed dispersal and pollination activities of fruit-and nectar-eating bats are vital
to the survival of rain forests, with some bats acting as “keystone” species in the lives of plants crucial to
entire ecosystems.
 Many plant bloom at night, using unique odors and special flower shapes to attract bats.
 One example is the famous baobab, which bats pollinate as they approach from below in a manner likely
to contact the flowers reproductive organs, while another is the Sausage Tree Kigelia Africana.
 By helping to rebuild cut forests, bats are also making sure other animals continue to have homes, shelter
and food.
 Wild varieties of many of the worlds most economically valuable crop plants also rely on bats for survival.
 Examples include wild bananas, breadfruit, avovados, dates, figs, peaches and mangoes.
 Although many of these are now commercially cultivated, the maintenance of wild stocks is vital as source
of genetic material for breeding disease resistant and productive varieties in the future.
 More than 300 plant species in the old world tropics alone rely on the pollinating and seed-dispersal
services of bats, providing more than 450 economically important products, e.g., the durian fruit southesst
Asia, sells for 120 million dollars each year and relies exclusively on flying foxes for pollination.
 The value of tropical bats in reforestation alone is enormous.
 Seeds dropped by bats account for up to 95% of forest re-growth on cleared land.

59. Scientific Value:
 Studies of bats have contributed to the development of navigational aids for the blind, birth control and
artificial insemination techniques, vaccine production and drug testing, as well as to a better
understanding of low-temperature surgical procedures.
 The saliva from the vampire bat is being studied to see if someday a new medicine can be found to
help people with heart problems.
Food Value:
 In many African and Asian countries, as well as certain Pacific Islands, bats are normal part of people
diets.
Uses of Bat guano:
 Bat guano an old faecal matter of bat can be used for bioremediation of sick aquatic ecosystem and for
waste water treatment.
 Bat guano has traditionally been used as fertilizer for crops in various parts of the world.