Crop damage by insects

how insect pest damages the crop

1. How Insects Damages The Crop ?
Dr.SubhomaySinha
M.Sc. (IARI), Ph.D. (IARI)

2. Why insects are so important ???
Insectsasagrouparehighlysuccessfulorganisms,because
:
(a)Theirtremendoussuccessinexistencerelativetootherorganismsexceptshuman
beings.
(b)Theirextremeimportancefromthehumanpointofview.

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.

6. This type of primitive insects still present today. e. g. Silverfish.

8. Evolution of insects, which can fold its wing.

9. Body divided into three regions
Arthropods= Insects and their relatives

10. CHARACTERISTICSOFANINSECT
1.Itpossesses3pairsofjointed
legs.
2Bodyissegmented.
3.Insectbodyisdividedinto3
regionsviz.,head,thoraxand
abdomen.
4.Itpossessesapairofcompound
eyes&antennae.
5.Twopairsofwingsarepresentin
adultstage.
INSECT
MITE

11. Life Cycle of Insects
Complete Metamorphosis
Incomplete Metamorphosis
Complete metamorphosis has four stages
Incomplete metamorphosis has three stages

13. Incomplete
INCOMPLETE
METAMORPHOUS
Insects change shape
gradually!

15. Complete
Metamorphosis
Four stages that all
look different

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
Fivetypesofmouthpartsareimportant
whenidentifyinginsects.
1.Chewing
2.Piercing-sucking
3.Rasping-sucking
4.Siphoning
5.Sponging

19. Chewing type of mouthparts
Chewinginsectscheworgrind
food.
Damagebychewinginsects
includestearing,cutting,
chewingorgrindingallpartsof
theplant.
Examples:Beetles,cutworms,
caterpillarsandgrasshoppers.
Chewing -mandibles

20. Piercing-Sucking type of mouthparts
Punctureplantandsuck
sapusuallyfromthe
undersideoftheleavesor
onthestem.
Damagecauseyellow
spottedleaveswhichresult
instuntedgrowth.
Examples:Aphids,mealy
bugs,mites,scaleand
whiteflies.

21. Rasping-Sucking type of mouthparts
Raspsorbreakstheleaf
surfaceandsucksap.
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
Havetwosponge-likestructuresthat
collectliquidfoodandmoveitinto
thefoodcanal.
Sponginginsectscancarrygermsor
diseasesthatcandamagetheplant.
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.
AKnowledgeofthefeedinghabitsofinsects,Whichfallintotwomaingroups
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 feederStem 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. InsectsFeedonthegrowingpointsofplantscausesretardedgrowth.
Eg:Grapevinebeetle–Scelodontastrigicollis
Shoot and growing point feeder

27. Tomato hornworms
Larvaearevoraciouseater,itconsumeseverything,
includingFruits,leavesandtendershootswith
growingpoint,leavingonlythestem.
Total plant feeder

28. Feed on the leaves and defoliate the plants causing reduction in assimilative leaf area and thus
hindered growth.
Eg: Semiloopercaterpillar 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
Notoriousforskeletonizingleavesofa
widevarietyofedibleandornamental
plants.Veinsarenoteaten,including
midriboftheleaves.Theymakes
differenttypesofholesonplantleaf.
SKELETONIZING LEAVES
Japanese beetles

31. SKELETONIZING LEAVES
Alfalfa weevil
Larvae skeletonizing leaves.

32. Theyconsumeentireleaf,including
venationandmidribs.Slugcaterpillars
arepestofMango,Castorandforest
crops.Thestartseatingfromthetipof
theleaf.
Slug caterpillar
CONSUME ENTIRE LEAF
INCLUDING MIDRIBS & VEINS

33. Colorado potato beetles
Theyconsumeplantfoliage,startingfrom
leafmargins,consumeeverythingincluding
themidribs.
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.

35. Cut off leaf cuticle in a
definite shape.
© A. Latchininsky 2006
Leaf cutter bee
Theleafcutterbeecutsaneatcircleor
ovalfromaleafcuticle.Theinsectuses
theseleafpiecestoweavetinycradles
foritseggsinsideitsnestburrow.

36. Grass hoppers (Hieroglyphusbanian)
Thisinsectdestroyplantleafbynotchingthe
edgeoftheleaves.Theyarepestofdifferent
cropslikerice,maize,vegetablesetc.
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

38. Stink bug damage
Stink bug eaten away leaf cuticle from
upper surface of the leaf.

39. Diamond back moth, (Plutellaxystella)
Larvae
Adult
Early instar larvae feed on a layer of surface tissue of the leaves, particularly in cabbage and
cauliflower.

40. Epilachnabeetle
Grub
Adult
Feedsuperficiallyonthesurfacetissueofleaf.
Thefeedingdamageiscalledladderlike
appearance.Bothadultbeetleandgrubdestroy
plantleaves.
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

42. Cabbage worms
Makes small holes of irregular shape and
size on leaf due to feeding on foliage.

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. Thelarvaefeedonthebarkofthe
plantsortreeswhilebeingconcealedin
aprotectivecoveringlikefrassand
excretainasilkenweb.
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. Thelarvaeofspottedpodborer–Marucavitratawebtheflowerbudsandflowersonred
gramandfeedonthem.
Feed on flower buds and flowers after making web with them
Spotted pod borer (Marucavitrata)

54. Cetoniidbeetles -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
Fergusoninaspp
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.
psyllidgall
psyllidgall

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
.
Helicoverpaarmigera
Helicoverpaon Sorghum.

62. LARVAE FEEDS ON THE GRAINS AND MAKES THEM
UNSUITABLE FOR CONSUMPTION.
Corn Earworm on maize
Larvae feeds on grains Completely damaged stalk

63. White grub insect
INSECT FEEDS ON ROOT
Grubs are root feeder.

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. Grubboreintotherootsoftheappletreeandfeedinternally.Severeinfestationofthisborer
cancausethedeathofthetree.Severeattackoccurredonsandysoil.
Apple root borer
ROOT BORING INSECTS
Infected plant
Adult insect

66. ROOT BORING INSECTS
GRAPE ROOT BORER
Larvae bores into root and
damage the crop
Larvae
Adult

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.
Brinjalfruit 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. Dioryctriaspp.
SHOOT BORING INSECTS
Larvae bores into apical growing parts of the shoot and disturb plant growth.

73. The stalk borer, Papaipemanebris
Insectsboreintoplantstalk
andcausingwitheringof
plant.Foundmostlyon
soybeanandsesame.
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

76. PSEUDOSTEM BORING INSECTS
Banana pseudostemborer
Adult and grub bore into the pseudostem
and destroy the crop.

77. FRUIT BORING INSECTS
Larvae bores into Ripe / un-ripe fruit and makes it unsuitable for consumption.
Larvae
Adult

78. Cottonbollworm Helicoverpa
armigera.Larvaeboresintocotton
bollandmakeitunfitforanyuse.
BOLL (FRUIT) BORING INSECTS

79. STONE (SEED) BORING INSECTS
Larvaeboreintothefruit,entersinto
thenut/stoneandfeedsinsideon
thestone/nutofthefruit.Thenut
getsrottenandfruitbecomes
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
Larvaeboreintothecabbagehead,reaches
growingpointandconsumeit.Nohead
formation.Fetchespoorreturn.
Hellulaundalis

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 secreatesHoneydew,
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

88. Aphid damage symptoms
Curling, twisting and distorted
leaf develops due to heavy aphid
infestation.

89. Aphid damage symptoms
Curling, twisting and distorted
leaf develops due to heavy aphid
infestation.

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.
Whitefliesaresmallinsectthattypicallyfeed
ontheundersidesofplantleaves.Whiteflies
feedbytappingintothephloemofplants,
introducingtoxicsalivaduringfeedingand
decreasingtheplants'overallturgorpressure.
Whiteflies

92. Whitefly infestation on tomatoes.
Whitefly infestation causing curling of
leaves with discoloration on tomatoes.

93. Scale insects
Thescaleinsects aresmallsuckinginsect.Mostscaleinsectsareparasitesof
plant,feedingonsap,drawndirectlyfromtheplant'svascularsystem.Causing
yellowspecklingonleaves.

94. Premature shedding of developing fruits
Scale insects damage symptoms
San Jose scale insect on apple.
Adultsandnymphssuckthesapfromtwigs,
branchesandfruits,resultingdroppingofpre-
maturefruitsanddryingofbranches.

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
Thripscausessilveringorwhiteningofleaf
surfaceduetoremovalofcellcontents
belowtheepidermiseg.Typicalleafdamage
causedbyThripsonpaddyandonion.
White feeding spots on
the leaves are caused by
thripsfeeding.
Thrips Damage

97. White feeding spots on the leaves
/ petals are caused by thrips’
feeding.
Thrips Damage
Thrips

98. Damage on Brinjal
Damage on Chilli
Thrips Damage

99. Lace wing bug
Thetinybugssuckthesapandcausechlorotic
spotsonleaves.

100. Hopperburnorcircularbrown
necroticspotsarecreatedby
contineoussapsuckingactionof
brownplanthopperinpaddyfield.
Brown plant hopper

101. Spittlebug damage
thenymphofthisinsectproducesacoveroffoamed-upplantsapresemblingsaliva/spit
andtheinsectsarethereforecommonlyknownasspittlebugs.
Thefoamservesanumberofpurposes.Ithidesthenymphfromtheviewof predatorsand
parasites,itinsulatesagainstheatandcold,thusprovidingthermalcontrolandalso
moisturecontrol.withoutthefoamtheinsectwouldquicklydryup.
nymph
Adult

102. Leafhoppers
Leafhopperssuckplantsapfromavarietyof
edibleandornamentalplantsandcauseleaves
tolosecolor,shineandbecomestippled.

103. Squash bugs
Theyhavepiercingmouthpartsthat
suckplantsapfromleaves,causing
yellowspotsonleavesthatwilloften
laterwilt,blacken,dieandfalloff.

104. Insects as vector of plant diseasesInsects as vector of plant diseases
Plant-infectingvirusesaretransmittedbyadiversearrayof
organismsincludinginsects,mites,nematodes,fungi,and
plasmodiophorids.
Thevirustransmission
cyclebyinsectinvolves
host-finding,feedingand
acquisitionofvirus,
transportanddeliveryof
virustoanewhostplant.
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 : HaddaBeetle
3.Name of the plant virus : Potato Virus X
4. Name of the disease : PVX disease.
Here the virus disease is spreadedby a
chewing type insect
HaddaBeetle
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 ( Myzuspersicae )
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 Tungrodisease.
Green leaf hopper
Rice Tungrodisease

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

117. Wheat field infected with Wheat Streak Mosaic Virus

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 : GemnivirusParticles
4. Name of the disease : Maize Streak Mosaic Disease.
Maize leaf hopper
Maize Streak Mosaic Disease

121. THANK YOU.