2. Why insects are so important ???
Insects as a group are highly successful organisms, because :
(a) Their tremendous success in existence relative to other organisms excepts human
beings.
(b) Their extreme importance from the human point of view.
3. How do insects fit in?
• Insects are the most populous and diverse
class of organisms in the animal kingdom.
– Make up over half of the living things on earth.
• Insects can live in almost every
environment.
– Land or water
• Insects are well adapted for all types of
environments.
4.
5.
6. This type of primitive insects still present today. e. g. Silverfish.
9. Body divided into three regions
Arthropods= Insects and their relatives
10. CHARACTERISTICS OF AN INSECT
1. It possesses 3 pairs of jointed
legs.
2 Body is segmented.
3. Insect body is divided into 3
regions viz., head, thorax and
abdomen.
4. It possesses a pair of compound
eyes & antennae.
5. Two pairs of wings are present in
adult stage.
INSECTMITE
11. Life Cycle of Insects
Complete Metamorphosis Incomplete Metamorphosis
Complete metamorphosis has four stages Incomplete metamorphosis has three stages
17. Different feeding behaviour are found in the insect
pests are :
• Defoliators
• Leaf feeders
• Leaf miner
• Sap suckers
• Root feeders
• Bark feeders
• Flower, nectar, pollen, and seed feeders
• Dead-wood feeders
• Gall makers
• Stem feeders
• Shoot borers
18. Insect Mouthparts
Five types of mouthparts are important
when identifying insects.
1. Chewing
2. Piercing-sucking
3. Rasping-sucking
4. Siphoning
5. Sponging
19. Chewing type of mouthparts
Chewing insects chew or grind
food.
Damage by chewing insects
includes tearing, cutting,
chewing or grinding all parts of
the plant.
Examples: Beetles, cutworms,
caterpillars and grasshoppers.
Chewing - mandibles
20. Piercing-Sucking type of mouthparts
Puncture plant and suck
sap usually from the
underside of the leaves or
on the stem.
Damage cause yellow
spotted leaves which result
in stunted growth.
Examples: Aphids, mealy
bugs, mites, scale and
whiteflies.
21. Rasping-Sucking type of mouthparts
Rasps or breaks the leaf
surface and suck sap.
Damage plant tissue becomes
speckled and white.
Example: Thrip.
22. Siphoning type of mouthparts
Dip a coiled tube into a liquid
food such as nectar and draw
(or siphon) it in.
Siphoning insects do little or
no damage to the plant.
Examples: Butterflies and
flies
Sucking - proboscis
23. Sponging type of mouthparts
Have two sponge-like structures that
collect liquid food and move it into
the food canal.
Sponging insects can carry germs or
diseases that can damage the plant.
Example: Housefly
24. Insects inflict injury to plants either directly or indirectly in their
attempts to secure food.
Almost all portions of plant viz. roots, stem, bark, shoots, leaves,
buds, flowers and fruits are attacked and damaged by insects.
A Knowledge of the feeding habits of insects, Which fall in to two main groups
1. Chewing insects
Theses insects cause direct effects & indirect effects
2. Sucking insects
INSECTS DAMAGE ALMOST EVERY PART OF A PLANT THAT SERVE AS FOOD.
25. Chewing insects
Chewing from outside
Foliage feeder Stem and bark
feeder
Flower and
flower bud
feeder
Fruit and seed
feeder
Root feeder
Tender shoot
feeder
Chewing from inside
Stem borer
Root borer
Fruit borer
Classification of Chewing insects
Insects chew off external and internal plants parts, grind them and swallow them.
They possess chewing and biting type of mouth parts.
26. Insects Feed on the growing points of plants causes retarded growth.
Eg : Grape vine beetle – Scelodonta strigicollis
Shoot and growing point feeder
27. Tomato hornworms
Larvae are voracious eater, it consumes everything,
including Fruits, leaves and tender shoots with
growing point, leaving only the stem.
Total plant feeder
28. Feed on the leaves and defoliate the plants causing reduction in assimilative leaf area and thus
hindered growth.
Eg : Semilooper caterpillar on castor
CONSUME ALL THE GREEN TISSUES, EXCEPT MIDRIBS AND VEINS
29. Feed on the leaves and defoliate the plants causing reduction in assimilative leaf area and
thus hinder growth.
CONSUME ALL THE GREEN TISSUES, EXCEPT MIDRIBS.
Red headed hairy caterpillar on groundnut & jute
Skeletonized leaf
30. Japanese beetles on cucumber
Notorious for skeletonizing leaves of a
wide variety of edible and ornamental
plants. Veins are not eaten, including
midrib of the leaves. They makes
different types of holes on plant leaf.
SKELETONIZING LEAVES
Japanese beetles
32. They consume entire leaf, including
venation and midribs. Slug caterpillars
are pest of Mango, Castor and forest
crops. The starts eating from the tip of
the leaf.
Slug caterpillar
CONSUME ENTIRE LEAF
INCLUDING MIDRIBS & VEINS
33. Colorado potato beetles
They consume plant foliage, starting from
leaf margins, consume everything including
the midribs.
CONSUME ENTIRE LEAF
34. This insect feeds on a variety of crops like Ragi, Drumstick,
Brinjal, Cotton etc. They Notches the edge of the leaves.
Ash weevil
NOTCHING THE SIDES
OF THE LEAF MARGINS.
36. Grass hoppers (Hieroglyphus banian)
This insect destroy plant leaf by notching the
edge of the leaves. They are pest of different
crops like rice, maize, vegetables etc.
NOTCHING THE SIDES
OF THE LEAF MARGINS.
37. Flea beetles create pinholes in leaves.
They are destructive pest in cruciferous
crops.
MAKE SMALL HOLES IN THE LEAVES BY
FEEDING
Flea Beetles
39. Diamond back moth, (Plutella xystella)
Larvae
Adult
Early instar larvae feed on a layer of surface tissue of the leaves, particularly in cabbage and
cauliflower.
40. Epilachna beetle
Grub
Adult
Feed superficially on the surface tissue of leaf.
The feeding damage is called ladder like
appearance. Both adult beetle and grub destroy
plant leaves.
FEED SUPERFICIALLY ON THE SURFACE TISSUE OF LEAF
41. Feed on tissue between upper and lower surface of leaf
MINES INTO LEAF EPIDERMIS AND FEEDS ON THE GREEN TISSUES.
Leaf miners
43. Leaves with large holes of irregular
shape and size due to feeding on
foliage.
Tobacco Caterpillar
44. ROLL UP THE LEAVES AND FEED WITHIN.
THEY SCRAP OFF THE GREEN PORTION OF
LEAF.
Paddy leaf folder
Damaged leaf
45. Leaf tiers: Larvae of several moth construct shelters by folding several leafs for
protection against predators such as birds.
LEAF TIERS
46. The larvae feed on the bark of the
plants or trees while being concealed in
a protective covering like frass and
excreta in a silken web.
Bark eating caterpillar
CONSUME BARK OF THE PLANTS /TREES
47. bark beetles
Bark beetles mine the inner bark (the phloem-
cambial region) on twigs, branches, or trunks
of trees and shrubs
CONSUME BARK OF THE PLANTS /TREES
bark beetle infested tree trunk
48. CONSUME BARK OF THE PLANTS /TREES
Longicorn beetle
GrubAdult
Grub bore into the stem and feed on inner parts, while adult feeds the bark of the stem
49. CONSUME BARK OF THE PLANTS /TREES
Larvae
Adult
Wood Wasp
Larvae bore through the stem and
feed on the inner parts.
50. Scarab beetles
CONSUME BARK OF THE PLANTS /TREES
Grub feeds on the underground portion of the woody
stem and damage the plant.
Grub
Adult
51. Cut the collar region of the tender plants at the time of germination or just after
germination. The insect is nocturnal, hide within the soil clod at daytime.
Cut worm
Cut the collar region of the tender
plants
52. Insect feed on flower buds and flowers causing reduced seed production and low yield.
Feed on flower buds and flowers
Blister Beetle
53. The larvae of spotted pod borer – Maruca vitrata web the flower buds and flowers on red
gram and feed on them.
Feed on flower buds and flowers after making web with them
Spotted pod borer (Maruca vitrata)
54. Cetoniid beetles - they feed on the flower buds and petals of rose
FEED ON THE FLOWER BUDS AND PETALS
55. FEED ON THE FLOWER BUDS AND PETALS
Jasmine bud worm.
Jasmine bud worm larvae
The larvae bore into flower buds and causing
shedding of petals.
Damaged flower
56. They Nibble and cut off ear heads of
paddy
Paddy Grasshopper
NIBBLE AND CUT OFF EAR HEADS
57. GALL FORMING INSECTS
Fergusonina spp
Galls are unusual plant growths, develop as a result of
abnormal cell division or cell enlargements after infestation
of plants by insects.
58. GALL FORMING INSECTS
Immature and adult stages of certain
insects are to be responsible for the
formation of special plant deformities
known as galls.
psyllid gall
psyllid gall
59. Eaten away entire foliage and
growing parts
Fall armyworm
COMPLETELY DESTROY THE CROP
60. They cut off ear heads of paddy.
They move in swarms and their
heavy infestation completely
destroy the paddy field
Completely devastated paddy field.
Paddy Armyworm or ear cutting caterpillar
COMPLETELY DESTROY THE CROP
61. PARTIALLY FEEDS ON THE GRAINS AND GIVE
CHAFFY APPEARANCE TO THEM.
Helicoverpa armigera
Helicoverpa on Sorghum.
62. LARVAE FEEDS ON THE GRAINS AND MAKES THEM
UNSUITABLE FOR CONSUMPTION.
Corn Earworm on maize
Larvae feeds on grains Completely damaged stalk
64. Insect chewing from inside of
the plant (Borer)
Root
Borer
Stored
grain borer
Nut /
Stone
borer
Pod
borer
Head
borer
Stem
borer
Soft stem
borer
Pseudostem
borer
Woody
stem
borer
Tuber
borer
Fruit
borer
Classification of Borer insects
65. Grub bore into the roots of the apple tree and feed internally. Severe infestation of this borer
can cause the death of the tree. Severe attack occurred on sandy soil.
Apple root borer
ROOT BORING INSECTS
Infected plantAdult insect
67. ROOT BORING INSECTS
Grub / Larvae bores into
root and damage the crop
Carrot Weevil
Adult carrot weevil
Damaged carrots
68. SHOOT BORING INSECTS : BORES INTO TENDER STEM.
Larvae bores into tender stem and feed
on the inner pith. The portion above the
boring point withers.
Brinjal fruit and shoot borer
69. SHOOT BORING INSECTS : BORES INTO TENDER STEM.
Yellow stem borer of paddy
Larvae bores into the stem and feed on the growing point. As a result dead heart
and white ear head develops.
Larvae
Adult moth
70. SHOOT BORING INSECTS : BORES INTO TENDER STEM.
Stem borer of Sugarcane
Larvae bores into the stem
and feed on the inner pith.
The portion above the boring
point withers.
Dead heart symptom of Sugarcane
71. Internode borer of Sugarcane
SHOOT BORING INSECTS : BORES INTO TENDER STEM.
Larvae bores into the stem by making hole in
the internode region and feed on the inner
pith. The portion above the boring point
withers.
72. Dioryctria spp.
SHOOT BORING INSECTS
Larvae bores into apical growing parts of the shoot and disturb plant growth.
73. The stalk borer, Papaipema nebris
Insects bore into plant stalk
and causing withering of
plant. Found mostly on
soybean and sesame.
SHOOT BORING INSECTS
74. TRUNK / WOODY STEM BORING INSECTS
Lemon tree borerLemon tree borer
Larvae bores into woody stem by making holes and feed on the internal content.
Damaged stem.
Adult
Larvae.
75. Larvae
Adult
Mango stem borerMango stem borer
Larvae bores into woody stem by making holes and feed on the internal content.
TRUNK / WOODY STEM BORING INSECTS
77. FRUIT BORING INSECTS
Larvae bores into Ripe / un-ripe fruit and makes it unsuitable for consumption.
Larvae
Adult
78. Cotton boll worm Helicoverpa
armigera. Larvae bores into cotton
boll and make it unfit for any use.
BOLL (FRUIT) BORING INSECTS
79. STONE (SEED) BORING INSECTS
Larvae bore into the fruit, enters into
the nut / stone and feeds inside on
the stone / nut of the fruit. The nut
gets rotten and fruit becomes
unconsumable.
Mango stone weevil.
80. CAPSULE (FRUIT) BORING INSECTS
Larvae bores into the tender capsule and
consume from inside. Causes heavy damage.
81. CABBAGE HEAD BORER
Larvae bore into the cabbage head, reaches
growing point and consume it. No head
formation. Fetches poor return.
Hellula undalis
82. POD BORING INSECTS
Insect pest of legumes. Larvae put its head into the pod and eaten away the seed inside the pod
83. TUBER (Modified underground stem) BORING INSECTS
Larvae tunnels into potato tuber, makes them
unfit for consumption as well as seed tuber.
84. STORED GRAIN BORING INSECTS
Grubs and beetles bore into stored grain, eaten away
the starch and make them unfit for consumption.
85. Sucking insects
These insecTs remain ouT side and wiTh Their mouTh parTs pierce
Through The epidermis and suck The sap
Many of the sucking insects, at the time of feeding inject their
salivary secretion which contains toxins. This toxin damages
the plant tissues further.
mosT of The sucking insecTs aTTack The leaves of planTs
86. Aphids
Aphids suck cell sap from
tender leaf, shoot, flower buds
and developing fruits.
Aphids secreates Honeydew,
that result in sooty mould
formation. .
87. General chlorosis is caused by
aphids and many of them cause
ultimate withering and drying of
the affected portions
Aphid damage symptoms
90. Honeydew is a sugar-rich sticky liquid, secreted by aphid
and some scale insects, as they feed on plant sap. When
their mouthpart penetrates the phloem, the sugary,
high-pressure liquid is forced out of the anus of the
aphid.
Sooty mould is the common name applied to
several species of fungi that grow on
honeydew, secreted by aphids on plant parts.
The fungi’s dark, threadlike growth gives plants
surface the appearance of being covered with
a layer of soot.
Honeydew
Ants feed on Honeydew
Sooty mould
Aphid damage symptoms
91. Yellow speckling of leaves may be produced
due to feeding of whitefly.
Whiteflies are small insect that typically feed
on the undersides of plant leaves. Whiteflies
feed by tapping into the phloem of plants,
introducing toxic saliva during feeding and
decreasing the plants' overall turgor pressure.
Whiteflies
92. Whitefly infestation on tomatoes.
Whitefly infestation causing curling of
leaves with discoloration on tomatoes.
93. Scale insects
The scale insects are small sucking insect. Most scale insects are parasites of
plant, feeding on sap, drawn directly from the plant's vascular system. Causing
yellow speckling on leaves.
94. Premature shedding of developing fruits
Scale insects damage symptoms
San Jose scale insect on apple.
Adults and nymphs suck the sap from twigs,
branches and fruits, resulting dropping of pre-
mature fruits and drying of branches.
95. Premature fall of fruits as in Citrus caused by the fruit
sucking moths
Adult insect suck sap from fruit and
causing premature shredding.
96. Thrips
Thrips causes silvering or whitening of leaf
surface due to removal of cell contents
below the epidermis eg. Typical leaf damage
caused by Thrips on paddy and onion.
White feeding spots on
the leaves are caused by
thrips feeding.
Thrips Damage
97. White feeding spots on the leaves
/ petals are caused by thrips’
feeding.
Thrips Damage
Thrips
99. Lace wing bug
The tiny bugs suck the sap and cause chlorotic
spots on leaves.
100. Hopper burn or circular brown
necrotic spots are created by
contineous sap sucking action of
brown plant hopper in paddy field.
Brown plant hopper
101. Spittlebug damage
the nymph of this insect produces a cover of foamed-up plant sap resembling saliva/ spit
and the insects are therefore commonly known as spittlebugs.
The foam serves a number of purposes. It hides the nymph from the view of predators and
parasites, it insulates against heat and cold, thus providing thermal control and also
moisture control. without the foam the insect would quickly dry up.
nymph
Adult
102. Leafhoppers
Leafhoppers suck plant sap from a variety of
edible and ornamental plants and cause leaves
to lose color, shine and become stippled.
103. Squash bugs
They have piercing mouthparts that
suck plant sap from leaves, causing
yellow spots on leaves that will often
later wilt, blacken, die and fall off.
104. Insects as vector of plant diseasesInsects as vector of plant diseases
Plant-infecting viruses are transmitted by a diverse array of
organisms including insects, mites, nematodes, fungi, and
plasmodiophorids.
The virus transmission
cycle by insect involves
host-finding, feeding and
acquisition of virus,
transport and delivery of
virus to a new host plant.
Mostly, Viruses are
transmitted into plant only
by sucking type of insects
105. Example of insect vector of plant virus diseases
1. Name of the plant : Cotton
2. Name of the insect vector : Whitefly
3. Name of the plant virus : Gemnivirus
4. Name of the disease : Cotton Leaf Curl Virus.
Whitefly
Cotton Leaf Curl Virus.
106. Example of insect vector of plant virus diseases
1. Name of the plant : Papaya
2. Name of the insect vector : Whitefly
3. Name of the plant virus : Gemnivirus
4. Name of the disease : Papaya Leaf Curl Virus.
Whitefly
Papaya Leaf Curl Virus
107. Example of insect vector of plant virus diseases
1. Name of the plant : Tomato
2. Name of the insect vector : Whitefly
3. Name of the plant virus : PRLV
4. Name of the disease : Tomato Leaf Curl Disease.
Tomato Leaf Curl Disease.
Whitefly
108. Example of insect vector of plant virus diseases
1. Name of the plant : Chilli
2. Name of the insect vector : Whitefly
3. Name of the plant virus : Gemnivirus
4. Name of the disease : Chilli Leaf Curl Disease.
Whitefly
Chilli Leaf Curl Disease
109. Example of insect vector of plant virus diseases
1. Name of the plant : Tomato
2. Name of the insect vector : Tomato Thrips
3. Name of the plant virus : TSWV
4. Name of the disease : Tomato spotted wilt virus Disease.
110. Example of insect vector of plant virus diseases
1. Name of the plant : Banana
2. Name of the insect vector : Banana aphid
3. Name of the plant virus : SSRNA Particle
4. Name of the disease : Banana bunchy top Virus.
Banana bunchy top Virus
Banana aphid
111. Example of insect vector of plant virus diseases
1. Name of the plant : Potato
2. Name of the insect vector : Hadda Beetle
3. Name of the plant virus : Potato Virus X
4. Name of the disease : PVX disease.
Here the virus disease is spreaded by a
chewing type insect
Hadda Beetle
Potato Virus X
112. Example of insect vector of plant virus diseases
1. Name of the plant : Potato
2. Name of the insect vector : Aphid (Myzus persicae)
3. Name of the plant virus : RNA virus
4. Name of the disease : Potato leaf roll disease.
Aphid
Potato leaf roll disease.
113. Example of insect vector of plant virus diseases
1. Name of the plant : Chilli
2. Name of the insect vector : Aphid
3. Name of the plant virus : CMV
4. Name of the disease : Chilli mosaic disease.
Aphid
Chilli mosaic disease
114. Example of insect vector of plant virus diseases
1. Name of the plant : Rice
2. Name of the insect vector : Green leaf hopper
3. Name of the plant virus : SSRNA Particles
4. Name of the disease : Rice dwarf disease.
Green leaf hopper
115. Example of insect vector of plant virus diseases
1. Name of the plant : Rice
2. Name of the insect vector : Green leaf hopper
3. Name of the plant virus : RTBV / RTSV
4. Name of the disease : Rice Tungro disease.
Green leaf hopper Rice Tungro disease
116. Example of insect vector of plant virus diseases
1. Name of the plant : Wheat
2. Name of the insect vector : Plant hopper
3. Name of the plant virus : WSMV
4. Name of the disease : Wheat Streak mosaic disease.
Plant hopper
Wheat Streak mosaic disease
118. Example of insect vector of plant virus diseases
1. Name of the plant : Wheat
2. Name of the insect vector : Wheat aphid
3. Name of the plant virus : BYDV (Luteovirus)
4. Name of the disease : Wheat Yellow Dwarf disease.
Wheat aphid
Wheat Yellow Dwarf disease
119. Example of insect vector of plant virus diseases
1. Name of the plant : Maize
2. Name of the insect vector : Small brown plant hopper
3. Name of the plant virus : DSRNA Particles
4. Name of the disease : Maize Rough Dwarf Disease.
Small brown plant hopper
Maize Rough Dwarf Disease
120. Example of insect vector of plant virus diseases
1. Name of the plant : Maize
2. Name of the insect vector : Maize leaf hopper
3. Name of the plant virus : Gemnivirus Particles
4. Name of the disease : Maize Streak Mosaic Disease.
Maize leaf hopper
Maize Streak Mosaic Disease
