Copy of types of damages
- 1. Welcome Dr.M.THIPpaiah Professor (Entomology) College of Agriculture ,G. K.V.K U.A.S , Bangalore-65
- 2. Types of damage to plants by different insect pests
- 3. Insects inflict injury to plants either directly or indirectly in their attempts to secure food and almost all portions viz., roots, stem, bark, shoots, leaves, buds, flowers, and fruits of plants 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 and indirect effects 2. Sucking insects
- 4. A. Direct effects of feeding I. Injury by chewing insects Insects which chew off external plants parts , grind them up and shallow them and they possess biting type of mouth parts and cause damage as detailed below : 1. Feed on the growing points of plants causes retard growth Eg : Grape vine beetle – Scelodonta strigicollis
- 5. 2. Feed on the leaves and defoliate the plants causing reduction in assimilative leaf area and thus hinder growth Eg : 1.Semilooper caterpillar, Achaea janata on castor
- 6. 2. Red headed hairy caterpillar, Amsacta albistriga on Ground nut
- 7. 3. Slug caterpillar, Latoia lepida on Mango and Castor
- 8. 3. Notch the edge of the leaves Eg : 1. Ash weevil – Myllocerus sp. feeding on a variety of crops like Ragi, Moringa, Brinjal, Cotton etc.,
- 9. 2. Grass hoppers - Hieroglyphus banian Feeding on maize Oxya spp.
- 10. 4. Make small holes in the leaves by feeding Eg : Flea beetle causes this type of damage on radish and Sunhemp
- 11. 5. Feed on a layer of surface tissue of the leaves Eg : Larvae of the diamond back moth, Plutella xystella on Cabbage and Cauliflower
- 12. Or feed superficially on the surface tissue Eg : Grubs and adults of epilchna beetle, Henosepilachna vigitioctopunctata on Brinjal and Bitter gourd
- 13. 6. Leaves with large holes of irregular shape and size due to feeding Cut worm – Spodoptera litura on Sun flower Soy bean semilooper, Thysanoplusia orichalcea
- 14. 7. Roll up the leaves and feed within Paddy leaf roller – Cnaphalocrocis medinalis Cotton leaf roller- Sylepta derogota
- 15. 8. 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 Eg : Bark eating caterpillar – Indarbela tetraonis on Mango, Moringa, Curry leaf , rain tree etc.,
- 16. 9. Cut the stem of the tender plants at the time of germination Eg : Surface weevil, Attactogaster finitimus attacks the seedlings of cotton raised under rainfed condition in black cotton soil Cotton shoot attack by weevil
- 17. Eg :1. Adults of blister beetle – Zonabris pustulata on red gram and Sesbania 10. Feed on flower buds and flowers and cause reduced seed production
- 18. 2. The larvae of spotted pod borer – Maruca vitrata web the flower buds and flowers on red gram and feed on them
- 19. 3. Cetoniid beetles - on rose feed on the flower buds and petals
- 20. 11. Nibble and cut off ear heads Eg : Rice grass hoppers
- 21. 12. Eat partially on the grains and give chaffy appearance Eg : Damaged by the larvae of Helicoverpa armigera to the ear heads of Sorghum and Finger millet
- 22. II. Injury by piercing and sucking insects These insects remain out side and with their mouth parts pierce through the epidermis and suck the sap The following symptoms or kinds of damage are caused by sucking insects by mode of feeding Many of the sucking insects, at the time of feeding inject their salivary secretion which due to presence of toxins damage the plant tissues further. 1. Most of the sucking insects attack the leaves of plants A general chlorosis is caused by aphids and many of them cause ultimate withering and drying of the affected portions
- 23. Eg : 1. Cow pea aphids – Aphis craccivora on Lab-lab, Ground nut, and Gliricidia
- 24. 2. Yellow speckling of leaves may be produced due feeding Eg : Castor whitefly – Trialeurodes ricini
- 25. Coconut scale – Aspidiotus destructor
- 26. 3. Silvering or whitening of leaf surface due to removal of cell contents below the epidermis Eg : Typical damage caused by thrips on paddy
- 27. 2. White feeding spots on the leaves are caused by thrips on Onion
- 28. White spots on the upper surface of the leaves caused by Stephanitis typicus on coconut
- 29. 4. Hopper burn or Necrotic brown lesion : Typical injury produced by leaf hoppers / plant hopper Eg : 1. Brown plant hopper – Nilaparvatha lugens on rice
- 30. 2. Cotton leaf hopper - Amrasca biguttula biguttula 3. Castor leaf hopper – Empoasca flavescens
- 31. 5. Crinkling or curling of leaves is caused by insects like Aphids , Thrips and leaf hoppers – Eg : Thrips , Scirtothrips dorsalis on Chillies
- 32. 6. Vitality of the plants gets reduced and premature dropping of leaves in case of Tomato whiteflies – Bemisia tabaci
- 33. Adults and nymphs suck the sap from twigs, branches and fruits Plant -weak, low yielding, death Fruits-grey mottled blemishes, reduces quality 7. Premature shedding of developing fruits or drying of shoots as in Scales and mealy bugs Eg: Sanjose scale on Apple
- 34. 8. Premature fall of fruits as in Citrus caused by the fruit sucking moths Eudicima phalonia E. materna
- 35. III. Injury by Internal feeders The internal feeders cause damage by remaining within the plant tissues during a part or all of their destructive stages The internal feeders may be grouped as Borers Worms or Weevils Leaf miners Gall insects
- 36. 1.Borers When the larvae feed on the wood or pith of the plant or part of the plant which may be generally large enough to contain the body of the pest , they are referred to as borers Eg : Larvae may bore in to the terminal shoots and cause death of the shoots as in the case of cotton boll worm – Earias spp.
- 37. Rice stem borer : Scirpophaga incetulas – Larva enter in to the stem and cause death of the central shoots i.e dead heart symptoms
- 38. Soghum stem borer – Chilo partellus larvae enter into the stem and cause death of the central shoots i. e dead heart symptoms
- 39. The stalk borer, Papaipema nebris on soy bean
- 40. The larvae bore into flower buds cause shedding such larvae are usually called bud worms Eg : Jasmine bud worm 2. Worms and Weevils :
- 41. The larvae may bore into the bolls 1. Cotton boll worm Helicoverpa armigera
- 42. Mango nut weevil, Sternochetus mangiferae feeding inside on the stone of the fruit Larvae may bore in to the nuts
- 43. Brinjal fruit borer Leucinodes orbonalis Larvae also bores in to the fruits feeds on inner contents
- 44. Castor capsule borer : Conogethes punctiferalis
- 45. 3.Leaf miners Larvae live in between the two epidermal layers of the leaves and feed on internal content , they are referred as Leaf miners
- 46. Eg : 1. Citrus leaf miner – Phyllocnistis citrella
- 47. 2. Cashew leaf miner – Acrocercops syngramma on Cashew
- 48. 3. Serpentine leaf miner – Liriomyza trifolii on Tomato
- 49. 4. Ground nut leaf miner – Aproaerema modicella
- 50. 4. Gall insects Immature and adult stages of certain insects are to be responsible for the formation of special plant deformities known as galls and these galls provide shelter and food to the insect Eg : Psyllid galls, Cecidomyiid galls ,Aphid galls
- 51. Psyllid galls
- 52. Psyllid galls
- 53. IV. Injury by Subterranean Insects Insects which are found in the soil live by feeding on the roots of plants and trees, by chewing or boring or sucking sap or Forming galls
- 54. Root grubs feeds on the roots of the plant
- 55. Root aphids feeds on roots of Ragi plants
- 56. V. Injury to Stored products In 3 ways the stored products are attacked by insects
- 57. 1. It may be continuation of a field attack In storage Hatching larvae bores into the tubers make tunnels in the tubers and infested tubers may be completely riddled by silk lined burrows, filled with larval larval excrement Field condition Larvae mine in to the petiole as a result drooping symptoms and finally produces blotches on the leaves Eg : Potato tuber moth Phthorimoea operculella
- 58. Eg: Sweet potato weevil – Cylas formicarius The grubs bores in to stems of vines cause tunneling inside and feed on soft tissues Grubs and adults bores into the tubers both in filed and storage gowdowns and affected tubers develop dark patches , which later start rotting
- 59. 2. The eggs may be laid in the field itself and damage may occur in the storage Some pulses are attacked by the Pulse beetle, Callosobruchus chinensis
- 60. 3. The infestation may continue from the material stored earlier carried over to fresh material stored later in godown or storage house Eg : Rice weevil - Sitophilus oryzae
- 61. Rice moth – Corcyra cephalonica on Maize It attacks broken grains and flours especially the milled products, which are heavily damaged if neglected
- 62. B. Indirect effects of feeding
- 63. 1. Making the harvest more difficult Heavy incidence of some pests on crops makes the harvest of the crop more difficult Eg : 1. Cabbage infested heavily with aphids
- 64. Red gram pods infested heavily with aphids and bugs
- 65. 2. Kapas from cotton bolls damaged by pink boll worm
- 66. 2. Causing contamination and loss of quality of the product Due to insect attack the final produce may show loss of quality by reduction in nutritional value or marketability
- 67. 1. Cardamom berries infested by thrips – Sciothrips cardamomi
- 68. 2. Sweet potato tubers riddled with holes caused by - Sweet potato weevil – Cylas formicarius
- 69. 3.Brinjal shoot and fruit borer Leucinodes orbonalis
- 70. 4. Amaranthus leaves skeletonized by larvae of Hymenia recurvalis
- 71. 5. Potato tuber moth - Phthorimoea operculella
- 72. 6.Cabbage with shot holes by the semilooper – Trichoplusia ni
- 73. 3. Disseminate plant diseases Insects are responsible for spreading many plant diseases caused by Bacteria, Fungi and viruses
- 74. Eg : 1. Paddy leaf hoppers – Nephotettix spp. – transmit viral disease like Rice tungro virus
- 75. 2. BPH – Nilaparvatha lugens – A vector of grassy stunt virus
- 76. 3. Bunchy top of banana – Transmit by aphid , Pentalonia nigronervosa
- 77. 4. Sterility mosaic virus of red gram transmit by Eriophyid mite, Aceria cajani
- 78. c. Injury by other methods 1. Injury by egg laying Insects takes a great deal of care in laying their eggs at the right place so that the young one will have enough food material for its development and thus survive
- 79. Cow bug, Oxyrachis tarandus adults and nymphs attended by ants Eg : Cow bugs insert their eggs into the plant tissue of the tender stem and thus cause injury
- 80. 2. Use of plant parts for making nests Some times parts of plant are removed by insects for the construction of their nests though they do not feed on them Eg: 1. Leaf cutter bee, Megachila sp.
- 81. 2. Tropical leaf cutting ants
- 82. 2. Tropical leaf cutting ants
- 83. 3. Red ants construct their nest
- 84. 3. Injurious insects being carried from one plant to another Ants and some other kinds of insects they are not injurious to crops by themselves , often carry the insects to other plants such injurious forms are aphids , mealy bugs etc;
- 85. Ants carry the aphids from one plant to the other plants
- 86. Red ants carry the mealy bugs from one plant to other plants
- 87. Thank you