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Pestssymptoms and Management



PESTS OF RICE SUCKING PESTS

  1. Thrips, Stenchaetothrips biformis, Thripidae, Thysanoptera

  2. Symptom of attack: Affected nurseries present a pale yellow colour with brown tips. On passing the wet palm over the top of the seedlings a large number of black adults and yellowish nymphs may be seen striking to the palm. The infestation invariably disappears after sharp showers. Nature of damage: Both the adults and nymphs lacerate the tender leaves and suck up the plant sap. As a result fine yellowish lines or silvery streaks are seen on the leaves. Later, the leaves curl longitudinally and begin to dry from the tip downwards. In severe cases, the entire nursery may dry up and fail to produce seedling. Sometimes transplanted crop is also affected in the early stages.

    Life stages

    • Egg:

    • Eggs laid singly in the tissues of the tender leaves on the sides facing the stem. Eggs are hyaline and turn pale yellow as they mature.

    • Nymph:

    • Newly hatched nymphs are transparent but turn yellowish white after the first moult and possess darker legs, head and antennae.

    • Adult:

    • Adult is 1 mm long, dark brown to black in colour with fringed wings. Male is smaller, more slender than female. It reproduces parthenogenetically since males are seldom seen in the population.


  3. Green leafhopper, Nephotettix virescens , Cicadellidae, Hemiptera

    • Symptoms of attack

    • Affected plants become pale yellow in colour and get stunted in growth. If the plants are tapped large number of leafhoppers may be seen jumping to water.

    • Nature of damage

    • Both nymphs and adults suck the plant sap from the leaf and leaf sheath. (It is a phloem feeder. Amino acid content is high in phloem sap than xylem. The xylem and phloem vessels are plugged with their stylet sheath that causes disruption in the transport of food substances in the vessels.) Mild infestation reduces the vigour of the plant and the number of reproductive tillers. Heavy infestation causes withering and complete drying of the crop. Plants are predisposed to fungal and bacterial infection through feeding and ovipositional punctures. Nymphs and adults exude sticky, whitish honeydew, which attracts sooty mould (that reduces the photosynthetic rate). It also transmits plant diseases such as dwarf, transitory yellowing, yellow dwarf and rice tungro virus (Tungro is transmitted during short feeding period).

      Life stages

    • Egg:

    • Greenish transparent eggs are deposited in the midrib of leaf blade or sheath of rice or green grass. They are laid in batches of 10 to 15 arranged in a single row.

    • Nymph:

    • The nymphs are soft bodied, yellow white in colour. Gradually the colour changes to green.

    • Adult:

    • Adults are 3-5 mm long, bright green with variable black markings, wedge shaped with a characteristic diagonal movement. Male insect has a black spot in middle of the forewings that is absent in females. The insect is active during July to September.


  4. Brown planthopper/ Fulgorid, Nilaparvata lugens, Delphacidae, Hemiptera

    • Symptom of attack:

    • Symptoms will not be visible from outside in the early stages, but if we enter the field and tap the plants large number of this insect can be seen. They are visible only when the damage has been severe, the plants present a burnt up appearance, hopper burn, in circular patches.

    • Nature of damage:

    • Both the nymphs and adults remain at the ground level and suck the plant sap. It is a typical vascular feeder primarily sucking phloem sap leading to hopper burn. At early infestation, circular yellow patches appear which soon turn brownish due to the drying up of the plants. The patches of infestation then may spread out and cover the entire field. The grain setting is also affected to a great extent. During sustained feeding, it excretes a large amount of honeydew. It also acts as vector of the virus diseases like grassy stunt, wilted stunt and ragged stunt. (Transmission of persistent ragged stunt and grassy stunt virus require more time. Sheath blight and stem rot incidence was high in BPH infested plants.)

    Life style

  5. Egg:

    • Eggs are laid in a group of 2 to 12 in leaf sheath (near the plant base or in the ventral midribs of leaf blades). White, transparent, slender cylindrical and curved eggs are thrust in straight-line in two rows. (They are covered with a dome-shaped egg plug secreted by the female. Only the tips protrude from the plant surface.)

    • Nymph:

    • Freshly hatched nymph is cottony white, 0.6 mm long and it turns purple-brown, 3.0 mm long in the fifth instar.

    • Adult:

    • Adult hopper is 4.5-5.0 mm long and has a yellowish brown to dark brown body. The wings are sub hyaline with a dull yellowish tint. It has two characteristic wing morphs: macropterous (long winged) and brachypterous (short winged). (Wing morphism is influenced by various factors viz., crowding during the nymphal stage and reduction in the quality and quantity of food, short day length and low temperature, which favour macroptery)


  6. Whitebacked planthopper, Sogatella furcifera, Delphacidae, Hemiptera

    • Symptom of attack:

    • Heavy infestation cause outer leaves of a hill to show burn symptoms. Damage in the form of hopperburn appears uniformly in a rice field, whereas it appears as circular patches in the case of BPH

    • Nature of damage:

    • WBPH is more abundant during the early stage of the growth of rice crop, especially in nurseries. (It attacks less than four-month old plants in fields with standing water and shows a marked increase with the age of the crop. Rice is more sensitive to attack at the tillering phase than at the boot and heading stages.) Damage is caused through feeding and oviposition. Gravid females cause ovipositional punctures in leaf sheaths. Both nymphs and adults suck phloem sap causing reduced vigour, stunting, yellowing of leaves and delayed tillering and grain formation. (Rice crop fails to produce complete grains [seedless glumes] and this condition is known as red disease in Malaysia.) Feeding puncture and lacerations caused by ovipositor predispose the plants to pathogenic organisms and

    • Egg:

    • Cylindrical eggs are laid in groups when the rice plant is small but in the upper part of the rice plant when the plant is large. (They are laid with the micropylar end protruding from the tissue, the operculum is long and narrow. The eggs in a group are not sealed together by the material secreted by female.)

    • Nymph:

    • White to a strongly mottled dark grey or black and white in colour and 0.6 mm size when young. Fifth instar nymph with a narrow head and white or creamy white body. Dorsal surface of the thorax and abdomen marked with various amounts of grey and white mark

    • Adult:

    • The adult hopper is 3.5-4.0 mm long. The forewings are uniformly hyaline with dark veins. There is a prominent white band between the junctures of the wings. Macropterous males and females and brachypterous females are commonly found in the field.


  7. Mealy bug, Brevennia rehi, Pseudococcidae, Hemiptera

    • Symptom of attack:

    • The infestation starts in plants one or two month after transplanting. Stunted, circular patches may be seen in the fields. If such plants are pulled out and teased the insects can be seen at the base of the leaves and leaf sheaths.

    • Nature of damage:

    • Large number of these insects’ remains inside the leaf sheaths and suck up the plant sap. The affected tillers remain stunted with yellowish curled leaves. When the attack is severe, it inhibits panicle emergence. This type of disease is called as Soorai disease in Tamil Nadu. The damage occurs from September. In severe cases, yield may be reduced even up

    • Egg:

    • The female lays numerous yellowish white eggs/ simply deposits nymphs in outer leaf sheaths.

    • Nymph:

    • The newly hatched nymphs crowded within the waxy threads for 6-10 h before they disperse to various parts of the same plant. The pale yellowish nymph is active and crawls about the plant for a while and settled itself on the plant/ stem and turns dark yellow after a day. Body gets covered with waxy material on second day.

    • Adult:

    • Nymphs and adults being wingless look alike. Females are reddish, oval, soft-bodied living in colonies inside the leaf sheath. Males are small, slender, pale-yellow, having single pair of wings and a style like process at the end of the abdomen but lack mouthparts. Males are seldom found in the colonies, so it reproduces parthenogenetically.


  8. Black bug, Scotinophara lurida, Podopidae, Hemiptera

    • Symptom of attack:

    • Presence of bugs at the base of the stem just above the water level. Plants stunted with reduced number of tillers; leaves turn reddish brown and dry.

    • Nature of damage:

    • The bugs remain and feed the plant sap on the base of the plants causing stunting of plants. Leaves turn reddish brown and grains do not develop. Bugs feed on the panicles in milky stage result in brown spots or empty grains in the panicles. Heavy bug infestation may cause death to the plants and whole field appears burned called bug burn similar to hopper burn.

    • Egg:

    • Eggs are cylindrical, greenish and laid in small groups of ten in two rows on the leave

    • Nymph:

    • Young nymph is brown with yellowish green abdomen and a few black spots.

    • Adult:

    • Adults are flat, 7-9 mm long, brownish black bugs with a prominent scutellum and pronotum having a spine on either side. It is active on the cloudy days and during night. Adults or late nymphal stage aestivate in cracks in bunds.


  9. Earhead bug/ Gundhi bug, Leptocorisa acuta, Alydidae, Hemiptera

    • Symptom of attack:

    • Leaves turn yellow and later rusted from tip downwards. Appearance of numerous brownish spots at the feeding sites / shrivelling of grains. In the case of heavy infestation, the whole earhead may become devoid of mature grains. Its presence in the field is made out by its strong smell.

    • Nature of damage:

    • Both adults and nymphs do the damage. The nymphs start feeding 3 to 4 hours after hatching. They feed on the leaf sap near the tip/ on milky sap in developing spikelets at milky stage. Sucking of the milky sap causes ill-filled/ partial filled and chaffy grains. Serious infestation can reduce the yield by 50%. The straw gives off-flavour that is unattractive to cattle.

    • Egg:

    • Eggs are circular, brownish seed like, 2 mm long, laid in clusters in two rows along the midrib on the upper surface of the leaf-blade.

    • Nymph:

    • First instar is small, 2 mm long, pale green in colour, which grows to deepen green through different instars.

    • Adult:

    • Adults are greenish yellow, long and slender, above ½ inch in length with a characteristic buggy odour.


  10. Earhead stink bug/ Shield bug/Red spotted bug, Menida histrio, Pentatomidae, Hemiptera

    • Symptom of attack:

    • Small dot like discoloration on the grains.

    • Nature of damage:

    • Both adult and nymph suck the sap/ milk of developing rice grain and cause pecky rice. (Grain discoloration is caused by subsequent infections of pathogenic fungi or bacteria on the sucking injuries and such grains are called as pecky rice). Sucking of this pentatomid bug causes comparatively small dot like discolorations on the grain than by L

    • Egg:

    • Eggs are laid in masses of 2-6 on leaves.

    • Nymph:

    • Nymphs are dark brown.

    • Adult:

    • It is a small brown bug with red and yellow spots.

      Minor pests:-

      1. White leafhopper, Cofana spectra, Cicadellidae, Hemiptera

      2. Nama vandu/ Stripped bug, Tetroda histeroides, Pentatomidae, Hemiptera

      3. Blue leafhopper, Empoascanara spp., Cicadellidae, Hemiptera

      4. Zigzag leafhopper, Recilia dorsalis, Cicadellidae, Hemiptera


    BORERS AND DEFOLIATORS

    1. BORERS

      • Paddy stem borer, Scirpophaga incertulas, Pyraustidae, Lepidoptera

      • Symptom of attack:

      • A number of stem borer moths seen dead and floating on the water in the fields. In the vegetative stage, dead hearts seen in the affected tillers and in the reproductive stage, whiteear may be seen.

      • Nature of damage:

      • The insect may start attacking the plants in the nursery especially long duration varieties. The incidence is mild in the season June to September, but later on gets intensified from October to January and February. The caterpillar enters the stem and feeds on the growing shoot. As a result the central shoot dries up and produces the characteristic dead heart. The tillers may get affected at different stages. When they are affected at the time of flowering the earheads become chaffy and are known as white ear.

      • Egg:

      • Eggs are creamy white, flattened, oval and scale like and laid in mass. Each egg mass consists of 15-80 eggs and covered with buff coloured hairs. Before hatching, the eggs darken to a purplish tinge. They are laid mostly near the tip of the leaves.

      • Larva:

      • The hatched larvae move downward and wander about on the plant for 1 or 2 hours. They may hang down by a sliver thread and get to other plants with the help of the wind. They can also swim over the water and reach other tillers. They enter the leaf sheath and feed upon the green tissues of the stem for 2-3 days. Then they bore into the stem near the node. Deposition of silica in the epidermal layer of the stem and leaf sheath acts as an obstacle to the first instar larvae to chew up a hole. Generally only one caterpillar is seen inside a tiller. It may come out and attack fresh tiller. The full-grown caterpillar measures about 20 mm, white or yellowish white in colour with a conspicuous prothoracic shield.

      • Pupa:

      • Pupation takes place inside the rice stem, straw or stubble. Before pupation it make a exit hole in the internode and covers it will a thin web for the adult to come out later. The anterior extremity of the cocoon is tubular and attached to the exit hole and to make the cocoon waterproof the larva webs two horizontal septa in this tubular area.

      • Adult:

      • They exhibit remarkable sexual dimorphism. The female moth is bright yellowish brown with a black spot at the centre of the forewing and a tuft of yellow hairs at the anal region. The male is small in size and brownish.


    2. Paddy gall midge, Orseolia oryzae, Cecidomyiidae, Diptera

      • Symptom of attack:

      • The central shoot instead of producing leaf produces a long tubular structure. When the gall elongates as an external symptom of damage, the insect will be in pupal stage and ready for emergence.

      • Nature of damage:

      • The maggot bores into the growing point of the tiller and causes abnormal growth of the leaf sheath, which becomes whitish tubular and ends bluntly. It may be pale green, pink or purplish. Further growth of tiller is arrested. This is called onion shoot, silver shoot or anaikomban. The feeding by the maggot and the larval secretion, which contains an active substance called cecidogen, is responsible for cell

      • Egg:

      • The fly lays elongate, cylindrical, shinning white or red or pinkish eggs singly or in clusters (2-6) at the base of the leaves.

      • Maggot:

      • Maggot is 1 mm long after hatching with pointed anterior end. It creeps down the sheath and enters the growing bud. An oval chamber is formed round the site of feeding.

      • Adult:

      • Pupa:

      • At the time of emergence the pupa wriggles up the tube with the help of antennal horn to the tip of the silver shoot and projects half way out.

      • Adult:

      • The adult fly is yellowish brown and mosquito like. The male is ash grey in colour. Adults feed on dewdrops.


    RICE DEFOLIATORS

    1. Swarming caterpillar: Spodoptera mauritia: Noctuidae: Lepidoptera

      • Symptom of attack:

      • Nurseries found completely eaten away by the caterpillars’ overnight.

      • Nature of damage:

      • Caterpillars march in large numbers in the evening hours and feed on the leaves of paddy seedlings till the morning and hide during daytime. They feed gregariously and after feeding the plants in one field march onto the next field. Under severe infestation crop gives the appearance of grazed plants. Attacked plants are reduced to stumps. Nurseries situated in ill-drained marshy areas attacked are earlier than dry ground. Damage is severe during July to September.

      • Egg:

      • Eggs are spherical and creamy in colour, which are laid in a group covered over with grey hairs.

      • Larva:

      • The caterpillars are light green with yellowish white lateral and dorsal stripes in the early stages and later become dark brown or grayish green in colour with a crescent (semi-circular) shaped black spot on the side of each segment.

      • Pupa:

      • They pupate inside the soil in earthen cocoons. Pupa is dark brown and measures 16-17 mm long.

      • Adult:

      • The adult moth is medium sized, stout built dark brown with a conspicuous triangular black spot on the forewings. Hind wings are brownish white with thin black margins.


    2. Rice case worm: Nymphula depunctalis: Pyraustidae: Lepidoptera

      • Symptom of attack:

      • Plants stunted, caterpillars hanging on the leaf edges in a tubular case.

      • Nature of damage:

      • The caterpillar cuts a piece of leaf, rolls it longitudinally into a tubular structure and remains inside. It feeds by scraping the green tissue of the leaf. The cases often float in the water. Its damage can be distinguished from damage by other pests in two ways, firstly the ladder like appearance of the removed leaf tissue resulting from the back and forth motion of the head during feeding and secondly the damage pattern is not uniform through out the field because the floating cases are often carried in the run off water to low lying fields where the damage is more concentrated.

      • Egg:

      • Eggs are light yellow, disc like, smooth and irregular in shape. They are laid on the under side of the leaves floating on the water.

      • Larva:

      • They hatch into green caterpillars with orange brownish head. Each caterpillar lives inside a tubular case and hang down the leaves. The tubular cases are open at one end. The inside of the case is lined with silk to hold a thin film of water, which is essential for respiration and preventing desiccation of the larvae. The cases are replaced with each moult. It moves up and down with the protruded legs and scrapes the green matter. It drops in the water when disturbed. It is semi aquatic and can breathe by filamental gills at the sides. Full-grown caterpillars measure upto 15 mm length.

      • Pupa:

      • It pupates inside the leaf case. Fresh pupae are milky white, which gradually turn to light yellow.

      • Adult:

      • The adult is a small delicate moth having white wings speckled with pale brown wavy markings. Females are larger than males. Egg laying takes place in the night.


    3. Rice skipper: Pelopidas mathias: Hesperidae: Lepidoptera

      • Symptom of attack:

      • Leaves folded longitudinally and scrapped patches in such places. Nature of damage: The caterpillar folds the leaves and feeds from inside. It feeds on the parenchyma and leaf gets reduced to skeleton. Occurs in the nursery and planted crop. Not a serious pest.

      • Egg:

      • Eggs are laid on the leaves.

      • Larva:

      • The caterpillar is elongate, yellowish green with four white dorsal stripes, smooth and with a constructed neck and red ‘V’ mark on the head, which is distinct.

      • Pupa:

      • Pale green pupa has white longitudinal lines on it and is attached to the leaf blade by a silk girdle.

      • Adult:

      • The adult is a dark brown skipper butterfly with two white spots on the wings.


    4. Leaf folder/ roller: Cnaphalocrocis medinalis: Pyralidae: Lepidoptera

      • Symptom of attack:

      • Leaves folded longitudinally or transversely with silk and scrapped patches in such places.

      • Nature of damage:

      • Larvae remain inside the fold and scrapping off green portion of the leaves leaving white patches.

      • Egg:

      • Flat oval yellowish eggs laid singly or in pairs on the undersurface of tender leaves.

      • Larva:

      • Larva is yellowish green in colour and translucent about 16-20 mm long. Pupa: It pupates inside the fold.

      • Adult:

      • Adult is small yellow coloured moth with dark wavy lines on both pairs of wings.


    5. Rice horned caterpillar: Melanitis ismene: Nymphalidae: Lepidoptera

      • Symptom of attack:

      • Defoliated leaves. It is a minor pest.

      • Nature of damage:

      • The larva feed on the paddy leaves at night, remaining inactive during daytime.

      • Egg:

      • Eggs are white, round laid singly on the paddy leaves.

      • Larva:

      • Larva is green in colour with roughened skin, flattened dorsally and has a dark brown head with a pair of red horn like processes and two yellow processes in the anal end. It feeds on the leaves.

      • Pupa:

      • Dark green chrysalis hangs from the leaf and is attached to the leaf blade by its anal extremity.

      • Adult:

      • The butterfly is dark brown with large wings having a few black and yellow eye-like markings one on each of the forewings and six ocellar spots on hindwings.


    6. Yellow hairy caterpillar: Psalis pennatula: Lymantriidae: Lepidoptera

      • Symptom of attack:

      • Defoliated leaves. It is a minor pest.

      • Egg:

      • Eggs are laid in batches on the leaves covered with yellow hairs.

      • Larva:

      • The caterpillar is yellow with red stripes and an orange head. Tufts of hairs are found all over, of which two in the anterior region and one in the posterior region are prominent.

      • Pupa:

      • Pupation is in a yellowish cocoon of hairs on the leaves.

      • Adult:

      • Moth is light yellow with bipectinate antenna.


    7. Grass hoppers : Hieroglyphus banian (Large grasshopper)

      • Symptom of attack:

      • The nymphs and adults nibble leaves and also earheads in the early stages.

      • Nature of damage:

      • Both the adults and nymphs feed on the leaf and in severe cases the entire leaf may be eaten away. It is capable of causing severe damage. In the earhead stage the adults nibble at the tender florets or grain or into the base of the stalks causing white ears.

      • Egg:

      • Life stages H. banian has only one brood in a year. O. nitidula breeds throughout the year. Egg: It lays eggs in the wet sandy soil during October to November at a depth of about 2”especially in the side of bunds. The eggs are laid in batches of 30-40, hatch only in June to July on receipt of the monsoon rains. Eggs are yellowish and covered with gummy substrate that hardens into a waterproof coating.

      • Nymphs:

      • The nymphs feed on the grasses or paddy

      • Adult:

      • They grow into adults by August to September. H. banian measures about 1½ inches long. There are three transverse dark lines on the prothorax, which is helpful for identifying the pest. O. nitudula is about one inch long and has a longitudinal brown streak on either side of the thorax.


    8. Spiny beetle/ Rice hispa: Dicladispa armigera: Chrysomelidae: Coleoptera

      • Symptom of attack:

      • The mining of the grubs will be clearly seen on the leaves. White parallel line will be clear on the leaves.

      • Nature of damage:

      • The grub mines into the leaf blade and feed on the green tissue between the veins. Adults also feed in the green tissue; they scrape the green matter of the tender leaves. Generally the plants are affected in the young stage.

      • Egg:

      • Eggs are laid inside minute slits on the tender leaves generally toward the tip. Grub: The grub is whitish yellow and flattened. It feeds inside the leaf tissue by mining. It pupates inside.

      • Adult:

      • The adult beetle is somewhat square shaped about 1/6 to 1/8” in length and width. Dark blue or blackish in colour with spines all over the body.


    9. Whorl maggot: Hydrellia sasakii: Ephydridae: Diptera

      • Symptom of attack:

      • Presence of feeding lesions in the lines and the infested plants become stunted.

      • Nature of damage:

      • The maggots are found to feed on the unopened leaves and to nibble the inner margins of the leaves, which showed conspicuous feeding lesions in the lines. Damaged leaves became distorted and broke-off in the wind. Infested plants are stunted. It cause damage to the boot leaf and developing panicles, which resulted in producing only partially filled/ half filled grains. Small puncture appear in the middle of the flag leaf and its margin get discolored.

      • Egg:

      • White, cigar shaped egg laid singly on either side of the leaves.

      • Grub:

      • Newly hatched larva is transparent to very light cream in colour but later become yellow. The larvae move down the leaf into the whorl on a film of dew and feed within developing whorls. The larvae mostly remain outside the leaves and feed on the mesophyll tissue of the foliage. When leaves emerge from the whorl damage can be seen as pinholes in the leaves and white and yellowish lesions on the leaf edge.

      • Pupa:

      • Pupation takes place in between the leaf sheath where the pupa is loosely attached to the stem. The puparium is light to dark brown ovoid and sub-cylindrical in shape.

      • Adult:

      • Adult dark grey flies, 1.8-2.3 mm in size.


    PESTS OF SORGHUM

    1. BORERS

      • Shoot fly: Atherigona varia soccata: Anthomyiidae: Diptera.

        • Symptom of attack:

        • Dead heats or drying of central shoots or production of profuse side tillers in main plants.

        • Nature of damage:

        • The maggots bore into the shoot of young plants, a week after germination to about one month and as a result the central shoot dries up. If the plants are attacked at the initial stages the mother plant may produce profuse side tillers, but the tillers also may be attacked. The infestation often goes as high as 60%. The high yielding hybrid varieties are severely attacked. In South India, crop is damaged during October to December as also in summer.

        • Egg:

        • Whitish eggs are laid singly on the under surface of the leaves which are about one week old.

        • Maggot:

        • The maggots are yellow in colour migrate to the dorsal surface of the leaf, enter the space between the leaf sheath and the axis and make a clear cut through the tightly rolled sheaths and damages growing point. The growing points of the plant die and decay on which the maggots feed.

        • Pupa:

        • Pupation takes place inside the stem itself.

        • Adult:

        • The adult is a small dark fly. Female fly has whitish grey head and thorax, while the abdomen is yellowish with paired brown patches. Male is darker in colour.

      • Stem borer: Chilo partellus: Crambidae: Lepidoptera

        • Symptom of attack:

        • Presence of circular holes on the unfolded leaves and dead hearts in the early stages are the main symptoms. The boreholes may be visible in contrast to the dead heart caused by the stem borer. When grown up plants are attacked the symptoms will not be quite visible.

        • Nature of damage:

        • The caterpillar bores into the stem and feeds on the central shoot. There may be more than one caterpillar in a single plant. In early stages, the caterpillars make circular holes on unfolded leaves and later central shoot dries up producing dead heart. Later it acts as an internode borer and is found till the time of harvest. Young cobs may also be attacked. Yield is affected much and the quality of the fodder is also reduced. The damage caused to the crop by this pest was estimated to range between 70 – 80%. Egg: Eggs are yellowish in colour, flat and oval, laid on the underside of the leaves, near the midrib.

        • Larva:

        • The larva is pale white with black dots and brown head. The newly hatched caterpillars migrate to the top of the plant and enter the stem or it mines in the midrib or bores into the stem near the node and feeds upwards. The larvae remain dormant in winter and hibernate. A caterpillar is dirty white with a brown head and thorax. There are four longitudinal stripes on its dorsal surface.

        • Pupa:

        • Pupation takes place inside the stem.

        • Adult:

        • Moth is medium sized and straw coloured. Male has pale brown forewings provided with dark brown scales forming a dark area along the coastal margin. Hind


      • Pink Stem borer : Sesamia inferens: Noctuidae: Lepidoptera

        • Symptom of attack:

        • Presence of dead heart.

        • Nature of damage:

        • The young larvae after hatching, congregate inside the leaf whorls and feed on folded central leaves causing typical ‘pin hole’ symptoms. Severe feeding results in killing of the central shoot and consequent dead heart formation. Usually the second instar larvae migrate to neighbouring plants by coming out from the whorls and suspending themselves from the plants by silken threads, these are then easily blown off by wind to other plants. These larvae penetrate in the stem and cause tunneling resulting in stunting, infested plants become weak and bear very small earheads. The weakened stems, especially of tall local varieties, break easily during heavy rains or with high velocity winds.

        • Egg:

        • Creamy white spherical eggs are laid in batches in between leaf sheaths and stem of a plant.

        • Larva:

        • The larvae penetrate the stems directly and may kill the young plants. The fully developed caterpillar is cylindrical, pinkish dorsally and whitish ventrally. Larvae can migrate from plant to plant.

        • Pupa:

        • Pupation occurs inside the stem, pupae are robust and light brown in colour.

        • Adult:

        • Adults are stout, straw coloured and are nocturnal in habit.


      • LEAF FEEDERS

        • Slug caterpillar: Thosea apierens: Cochlididae: Lepidoptera

        • Symptom of attack:

        • Defoliation.

        • Nature of damage:

        • They feed on the leaves and defoliate. Apart from this they cause lot of irritation on the people who work in the field. Harvest is made difficult and it is reported the even cattle do not relish the fodder.

        • Lifestage:

        • Slug is found to appear in a severe form in Coimbatore.


      • Leaf roller: Marasmia trapezalis : Pyralidae: Lepidoptera

        • Symptom of attack:

        • Rolled up leaves in which the larvae are found feeding and longitudinal patches on leaves whose tips dry are the clear symptoms.

        • Nature of damage:

        • The leaf roller becomes quite serious on young crops and feeds on the leaf epidermis. It causes longitudinal patches on the leaves and the tips of the leaves dry up. It is only a minor pest and rarely becomes serious. The varieties with broad leaves are attacked more severely.

        • Egg:

        • Eggs are laid on young leaves.

        • Larva:

        • A caterpillar is greenish yellow and is provided with setae over its body. Head and thoracic shield are brownish in colour. When full grown the caterpillar measures about 20 mm.

        • Pupa:

        • Pupation takes place within the rolled leaf.

        • Adult:

        • Adults are grayish with shining coloured patterns. Anal margins are darker in colour.

      • Flea beetle: Cryptocephalus schestedti : Chrysomelidae: Coleoptera

        • Symptom of attack:

        • Shot holes.

        • Nature of damage:

        • The pest occurs in small number is feeding on the leaves. It nibbles small holes on the leaves.

        • Life stages:

        • This is an yellow beetle with long black streak. M. signata: Adult is a black beetle with four yellow spots.

        • Monolepta signata:

        • Chrysomelidae: Coleoptera Symptom of attack: Shot holes.


      • SAP FEEDERS

        • Shoot bug : Peregrinus maidis : Delphacidae: Hemiptera

        • Symptom of attack:

        • The leaves turn yellow due to sucking; plants become weak and the yield goes down. The mid rib of the leaves become red due to egg laying and may dry up subsequently.

        • Nature of damage:

        • Both adults and nymphs suck the plant sap from the leaves and cause the shoot to dry. They feed gregariously within the leaf sheaths. It is not a serious pest, but sometimes causes appreciable damage.

        • lifestage:

        • It is a small active, grayish brown bug. Colonies of this bug (both adults and nymphs) live within the whorl of the central leaf or in the root region. This pest is very common in Coimbatore during summer. The large black ant attends these insects.


      • Plant lice: Rhopalosiphum maidis, Longuinguis sacchari : Aphididae: Hemiptera

        • Nature of damage:

        • Nymphs and adults suck plant sap from the leaf, leaf sheath and inflorescence. They occur in cluster and may cause severe damage to inflorescence by hampering pollination. The aphid colony secretes honeydew in plenty.

        • Life stage

        • The former one is yellow with dark green legs and lives inside the central leaf. The latter is creamy and lives on the under the surface of lower leaves. These are not serious pests. Reproduction parthenogenetic. Cloudy and humid weather favours reproduction.

      • Earhead bug: Calocoris angustatus : Miridae: Hemiptera

        • Symptom of attack:

        • No external symptom will be visible. The earheads should be tapped either on the palm or a piece of cardboard. A number of brownish or greenish nymphs and adults can be seen. On the developing grains small brownish spots will be visible. In severe infestation, the grains get shriveled without maturing and the earheads appear uneven.

        • Nature of damage:

        • The adults and nymphs live inside the earhead and suck the milky fluid from the tender ripening grains. Due to the feeding, the grains get shriveled and chaffy and thus unfit for sowing and for consumption. No damage is caused to fully ripened grains. A reduction of 15 – 30% in the yield was estimated due to its attack. Usually high yielding varieties with compact earheads (Chitrai cholam) are subjected to more infestation than the loose earheads.

        • Egg:

        • The female bug thrusts shining pale yellowish cigar shaped eggs into the tender tissues of the shoot between glumes in the centre of the florets.

        • Nymph:

        • The newly hatched nymphs have light orange red abdomen, which changes to green in the advanced instars.


      • Mirid bug: Creontiades pallidifer: Miridae: Hemiptera

        • Nature of damage:

        • It is a minor pest. Nature of damage is similar to earhead bug..


      • Sorghum midge: Contarinia sorghicola: Cecidomyidae: Diptera

      • Symptom of attack:

      • The flowers appear damaged; earheads are devoid of grains and during severe attack, may appear blighted.

      • Nature of damage:

      • This fly attacks the developing grains. The larvae develop by feeding inside the grains. This results in the failure of grain formation causing them to shrivel during serious infestation the entire earhead may appear to be blighted or blasted. This pest is a minor pest and assumed major pest status after the introduction of CSH 1 hybrid cholam.\

      • Egg:

      • Eggs are laid inside the glumes of closed or open flowers.

      • Maggot:

      • The newly hatched maggot feed on the ovaries. The advanced stage larvae are pink in colour.

      • Pupa:

      • pupate inside the damaged flowers.

      • Adult:

      • pupate inside the damaged flowers.


    2. Gram caterpillar: Helicoverpa armigera: Noctuidae: Lepidoptera

      • Nature of damage:

      • Caterpillars feed on the grains at the time of maturity causing considerable damage.


    3. Other pests

      • Red hairy caterpillar:

      • Amsacta albistriga: Arctiidae: Lepidoptera

      • Angoumois grain moth:

      • Sitotroga cerallela: Gelechiidae: Lepidoptera

      • Cryptoblabes sp.:

      • Pyralidae: Lepidoptera

      • Flower webber:

      • Eublemma silicula: Noctuidae: Lepidoptera

      • Dolicoris indicus:

      • Nezara viridula: Pentatomidae: Hemiptera

        These pests are found on the earheads in the milky stage. The injury is only very little.


      INTEGRATED PEST MANAGEMENT

      Integrated Pest Management (IPM) is a system that in the context of associated environment and population dynamics of the pest species, utilizes all suitable techniques and methods in as compatible manner as possible and maintains the pest populations at levels below those causing economic injury.

      COMPONENTS OF IPM

      1. Pest monitoring and surveillance

        • Monitoring

          • identification of major pests in the area along with its time of occurrence and life cycle.

            identification of natural bio-agents that include predator and parasites in relation to pests.

        • surveillance

        • samples of population of insect pests are to be taken

          • Manually from plant samples

          • By insect net

          • By water pan method


      2. cultural methods (agronomic practices)

        • crop rotation

        • tillage

        • trap crops

        • intercropping

        • Pupa:

        • altered timings

        • clean culture

        • soil manuring& fertilization

        • pruning and thining

        • Growing resistant varieties

        • proper spacing


      3. Physical & Mechanical methods

        • Destruction of pest through hand picking

        • Rouging-removal of affected part

        • By hoeing, trenching ect.,

        • By shaking or jarring

        • use of hand nets

        • sieving& winnowing

        • flooding & Draining

        • banding

        • cooling & heating/p>

        • wire gauge screens


      4. Bio-control methods

        • conservation of identified bivalents in the field con dition by avoiding pesticides upto the crop age 30-35 days.

        • augmentation/release of natural bio-control agents in the required quantities in the problemssssfiedlds.

        • protection & encouragement of natural enemies.

        • propagation and dissemination of specific bacteria (Bacillus thurigiensis), Viral (N.P.V), & protozoan of insects.

        • use of pheromone traps


      5. chemical methods

        • A sequence of alternative insecticides based on genetic considerations of cross resistance and multiple resistance should be chosen.

        • Use of environmental friendly and comparatively safe pesticides.

        • Insecticide formulations, application methods and time of application are important for effective integrated control programmes.

        • Pest specific pesticides should be selected.

        • Spraying of pesticides should be stricitly as per the required does.

        • Use of proper spray nozzies.


    Some of the potential biotic agents for pest control of the cultivated crops


    CROPS

    PESTSS

    Potential biological control agents

    Sugarcane

    Pyrilla

    Boiri ania, Tetrastichus pyrillae

    Borers

    Trivhogramma chilaonis

    Top shoot borer

    T. japonicum (one lakh.ha.wk)

    Scale insect

    Lady bird beetle (Chocerus nigrutus) and Pharoscymnus hornu (each 15000/ha).

    Cotton

    Aphid, white flies

    Chyrysoperla carnea (50,000 to 1lakh/ha) two times 45th and 130th day and 3rd at 260th day.

    Sugarcane

    Pyrilla

    Boiri ania, Tetrastichus pyrillae

    Boll worms

    T. chilonis (1 ½ lakhs/ha from 70th day)8-10 releases.

    Sugarcane

    Pyrilla

    Boiri ania, Tetrastichus pyrillae

    Gram and Tur

    Pod borer

    Chrysoerla chilonis (50,000/ha), Bracon Nuclear poyhedrosis virus (NPV@ 125 or 250 LLE/ha)

    Tomato

    Fruit borer

    Chrysoperla, chilonus, Bracon trichhogramma (40,000/ha), at weekly interval NPV (250LE/ha)

    Potato

    Leaf, miner, Aphid,jassid, White fillies Thrips Tuber moth

    Chelonus blackburni, Copidosoma Koechleri, T. chilonis (50,000/ha), Any one four times at 10days interval. Bacillus thuringiensis 0.05% spray.

    Coconut

    Black headed Caterpillar

    Bracon, Parasierola

    Tobacco

    Aphid, caterpillar White fly

    Chrysoperla carnea (1lakh/ha), Twice during the season with an Interval of 15days.

    Sunflower

    Head borer, aphid

    Chrysoperla carnea (1lakh/ha), Twice during the season with an Interval of 15days.


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