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Insects pests of maize

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Insects pests of maize

  1. 1. INSECT PESTS OF MAIZE R. Regmi Assistant Professor Department of entomology
  2. 2. Major insect pests • Maize stem borer, Chilo partellus (Lepidoptera: Pyralidae) • White Grub, Phyllophaga rugosa/Holotrichia spp./Anomala dimidiate (Coleoptera: Scarabaeidae) • Rice Ear- cutting caterpillar, Mythimna separata (Lepidoptera: Noctuidae) • Flower Beetle, Chiloloba acuta (Coleoptera: Cetonidae) • Wireworms, Agriotes spp (Coleoptera: Elateridae)
  3. 3. 1. Maize stem borer 2, 3. White grub 4,5. Rice ear cutting caterpillar, Armyworm 6. Pollen beetle
  4. 4. Minor insect pests • Rice Grasshoper, Hieroglyphus banian (Orthoptera: Acrididae) • Grey Weevil, Myllocerus undecimpustulatus (Coleoptera: Curculionidae) • Maize Cob worm, Helicoverpa armigera (Lepidoptera: Noctuidae) • Cutworm, Agrotis segetum / A. ipsilon (Lepidoptera: Noctuidae) • Leaf folder, Marasmia trapezalis (Lepidoptera: Pyralidae) • Flea beetle, Monolepta signata (Coleoptera: Chrysomelidae) • Maize shoot fly, Atherigonna spp. (Diptera: Muscidae) • Banded blister beetle, Mylabris phalerata (Coleoptera: Meloidae)
  5. 5. Continue minor insects • Pink borer, Sesamia inferens(Lepidoptera: Nocutidae) • Green Horned caterpillar, Melanitis leda ismene(Lepidoptera: Satyridae) • Maize aphid, Rhopalosiphum maidis (Homoptera: Aphididae) • Field cricket, Brchytrupes portentosus (Orthoptera: Gryllidae) • Seed Bed Beetle, Heteronychus lioderes (Coleoptera: Dynastidae)
  6. 6. Rice Grasshopper Helicoverpa Cutworm Maize shoot fly
  7. 7. Maize aphid Armyworm Banded blister beetle
  8. 8. Maize stem borer, Chilo partellus (Lepidoptera: Pyralidae) • Most destructive pests of maize and sorghum. • Its caterpillar damage maize and sorghum by boring into the stems, cobs or ear. • The grown up caterpillar are about 20-25 mm long and dirty greyish white with black head and four brownish longitudinal stripes on the back. • The adult are yellowish grey moths, about 25mm across the wing when spread.
  9. 9. Life cycle: • The insect breeds actively from March- April to October. • The rest of the year it remains in hibernation as full grown larva in maize stubble, stalks or unshelled cobs. • The larva pupate sometime in March and emerge as moths in the end of that moth or in early April. • They are active at night, when they mate and lay eggs on the underside of the leaves of various hosts plants, particularly the early crop of maize. • The eggs are flat oval, yellowish and are laid in overlapping clusters each containing up to 20 eggs. • A female lays over 300 eggs during its life span of 2-12 days and the egg hatch in 4-5 days in summer.
  10. 10. Continue life cycle • The young larva first feed on the leaves making a few shot holes and then bore their way downward through the central whorl as it opens. • More shot holes becomes visible, indicating an earlier attack and the plant also shows dead heart. • The larva becomes full fed in 14-28 days, passing through six stages and after making a hole in the stem pupate inside it. • The life cycle is completed in about 4-7 weeks and there are probably 5 generation in a year. • The full grown caterpillar of the last generation hibernates in stubble, stalks etc. and remain there till next spring.
  11. 11. Damage • The damage is done by the caterpillars by eating inside of the stem. • Production of dead hearts, weakening of the plants are the symptoms of attack of any stem borer.
  12. 12. Management • Destroying the stubble, weed and other alternate hosts of the stem borer by ploughing field after harvest. • Removal and destruction of dead hearts and destruction of infested plants showing early pin hole damage. • Destruction of crop residues and chopping and stem harbouring diapauses larva could be effective. • Clipping of lower leaves of maize (upto 4th ) • Release Trichogramma chilonis @one lakh per ha on 10-15 days old maize field crop. • Spray crop 2-3 weeks after sowing as soon as borer injury to the leaves is noticed with either of Fenvalerate 20EC @100ml/ha, Cypermethrin 10EC@100ml/ha or deltamethrin 2.8EC@200ml using 150 liters of water. • Use granular pesticide Furadan 3%G@12-15kg/ha
  13. 13. White grub, Phyllophaga rugosa (Coleoptera: Scarabaeidae)  White grubs are the larva of scarb “chafer” beetles.  They are creamy white in color, C- shaped with brown head with 3 pair of thoracic legs.  Some species of white grubs (Phyllogphaga spp.) feed on roots of maize plants.  Root damage is manifested by wilting seedling, poor plant stands, patches of tilted or lodged plants showing uneven growth.  Injured plants can easily be pulled out from ground.  The third instar is often the most damaging one and may be present in the soil for longest time.  The extent of damage and species composition varies from place to place.  The larva is the major damaging stage but adults also damage the leaf during night time.
  14. 14. Life Cycle  Generally, most beetles takes 3 years to complete their life cycles in temperate regions but only 2 years in optimum soil temperature.  Female white grubs lay the eggs in soil in pasture land or in fresh dung.  Hatching of egg takes place after 2-3 weeks.  First instar larva begin to feed on organic matter after hatching, later feed on plants roots.  With cooling soil temperature, larva descends into the soil profile, where they spend the winter.  In the spring, larvae begin their upward migration as soil temperatures increases.  The larval period ranges from 9-21 months and pupal period is 3-6 months.
  15. 15. Management • Different cultural practices such as ploughing, harrowing, hoeing, flooding and fallowing of field. • The use of well decomposed Farm yard manure (FYM). • Light traps can be used for collecting adults beetles during night. • Use of Metarrhizium and Beauveria based biopesticide (1- 1 kg of Metarrhizium & beauveria mixed with 25 kg of FYM and kept for 8 days in shade. Using this during land preparation). • In Highly affected area, use Chloropyriophos 10 G @ 1kg per Ropani before sowing. • Treat the seed before sowing with 12.5ml of Chorpyriphos 20EC per Kg of seed. • Kills the beetles by spraying 500g of carbaryl 50WP in 250 liter of water per ha on preferred host like Zizyphus, Guava, Grapevine etc. • Apply 30Kg of carbofuran 3G per ha in the soil at or before sowing.
  16. 16. Armyworm, Mythimna separate (Lepidoptera: Noctuidae) • The armyworm is a pest of graminaceous crops all over the world mainly pests of maize, wheat, sugarcan, jowar, bajara. • The larva feed voraciously and migrate from one field to another.
  17. 17. Life cycle: • The adult moths of armyworm are pale brown. • They live for 1-9 days and lay eggs singly in row or in clusters on dry or fresh plants or on the soil. • The eggs are round, light green when freshly laid and turns pale yellow and finally black. • The egg hatch in 4-11 days from March to May and in 19 days in December- January. • Freshly emerged larva are very active, dull white and later turn green. • In the spring, the larval stage is completed in 13-14 days, but in winter it is prolonged to 88-100 days. • In the pre-pupal stage, the insect spins a Cocoon.
  18. 18. Continue life cycle • The pre-pupal stage last 1-11 days during January to May. • Pupation usually takes place in the soil at a depth of 0.5- 5 cm, but it may also occur under dry leaves among the stubble or fresh tillers. • Generally, the larva before pupation seem to select sites near the water channels. • The pupal stage is completed in 9-13 days in May and 36-48 days in the winter months. • The survival of the pupae depends on soil moisture. • The population build up starts in the beginning of March & increase with the rise of temperature in the spring.
  19. 19. Damage • In the early stages, they feed on tender leaves in the central whorl of the plant. • As they grow, they are able to feed on older leaves also and skeletonize them totally. • The grown up caterpillar throw out faecal pellets, which are quite prominent. • In case of a severe attacks by the armyworm, whole leaves including the mid rib, are consumend and field look as if grazed by cattle. • The larva of all instars feed mainly on leaves. • Fourth and older instars larvae cause the main harm, roughly gnaw out and eating around the leaf blade and damaging inflorescences, ears, growth points and grain in ears .
  20. 20. Management: • Collecting and destroying the caterpillar. • Spray 500ml of dichlorovous 85 SL or 3 Kg of carbaryl 50WP or 1 Lit of Quinalphos 25EC in 250 Liters of water per ha.
  21. 21. Flower beetle, Chiloloba acuta (Coleoptera: Cetonidae) • They are pollen feeders and are common on flowers and may occur under loose bark in debris. • Flower beetle caused damage in rice, maize, sorghum, millets etc. • They also feed on the leaves, bud and flower. • The main injury consists in feeding and destroying blossom petals. • If many beetles are present, their excrement often discolor the blossom.
  22. 22. • The adult beetles are shiny metallic green and appear sometimes red or deep blue. • The are irregularly covered with hairs on the upper side but more densely on the sides and underside.
  23. 23. Life cycle: • Female lays hundreds of tiny, oval eggs, usually on a leaf or in rotten wood, which usually takes 4-10 days to hatch. • The larva pass through 3-5 instars, they vary in shape and size depending on where they live and what they feed on. • They generally appears grub like with a well defined head capsule, which may be highly sclerotised. • The larvae of Chiloloba species feeds on trunks, branches or twigs of dying plants. • The pupal stage is usually found during the winter period and adult emergence occurs in spring.
  24. 24. Management • Hand collection of adults beetle • Collection with help of sweep nets • Spray 500ml of dichlorovous 85 SL 1 Lit of Quinalphos 25EC in 250 Liters of water per ha.
  25. 25. Wireworms, Agriotes spp (Coleoptera: Elateridae) • Wireworm is the common name of the larva of click beetle. • The name ” click beetle” originates from the habit of clicking its body into the air. • The adult beetle are harmless feeding on pollen, however, the larva belongs to the most destructive soil insect pests. • They are important pests of potatoes and other crops including cereals & also damage germinating seeds. • Most adult are light to dark brown and dull, between 6 to 10 mm long and about 2 mm wide. • The body of the beetles is convex. • The egg are white, nearly globe shaped about 0.5 mm in diameter. • The larva are dark yellow up to 25mm long and 2 mm wide. The apex of the last segment of the larval body is sharp pointed. • The larva are hard, nearly cylindrical and shining as those in all the species. • Pupae are white 9-12 mm long.
  26. 26. Life cycle • The females lay eggs in cluster or singly on roots or into soil at a depth of 3-15 cm. • The total female fecundity amounts to 50-350 eggs. • The larva develops during 3-5 years, molting 8-11times. • Overwintering takes place at a soil depth of 20-50cm. • The larvae prefer moist soils, As soils dry out, they migrate in deeper soil layer. • Larger larvae are able to starve several months. • A generation lasts 3-6 years depending on food availability and environmental conditions.
  27. 27. Continue Life cycle • Plants in unploughed soil and grassland represents the primary food source for wireworm. • Therefore, problems arise when infested pastures are ploughed and planted with crops. • Because of their extended life cycle, wireworm damage may persists for 2-3 years after. • The most significant damage is caused to germinating seeds and seedling during cold, wet springs. • Wireworm injury is often associated with a small feeding hole at the base of the plant, which may kill the growing point and stunt plant growth.
  28. 28. Damage • The wireworm feed on seeds, seedling and underground parts of crops & weed. • The wireworm are more harmful for the grain cereals, especially for maize, sunflower, potato, Solanaceous and Cruciferous vegetables, carrot, beet, turnip etc. • Wireworm cause shoot thining, stunting of damaged plants and quality loss of tuber crops like potato.
  29. 29. Management • Crop rotation that include alfa-alfa and high glucosinolate Brassica spp may help in management of wireworm. • Field drying and summer ploughing • Flooding field with water at least for 2 weeks • Use of wheat as trap crop while growing maize and other cash crops • Use of Metarrhizium and Beauveria based biopesticide (1- 1 kg of Metarrhizium & beauveria mixed with 25 kg of FYM and kept for 8 days in shade. Using this during land preparation).

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