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pests of lepidopteran
- 2. Lepidoptera • The Lepidoptera is an order of insects that includes moths and butterflies (both are called lepidopterans). • Lepidopteran species are characterized by more than three derived features, some of the most apparent being the scales covering their bodies and wings, and a proboscis.
- 3. • butterflies and moths are holometabolous, meaning they undergo complete metamorphosis. • The larvae are commonly called caterpillars, and are completely different from their adult moth or butterfly forms, having a cylindrical body with a well-developed head, mandible mouth parts, three pairs of thoracic legs and from none up to five pairs of prolegs. • As they grow, these larvae change in appearance, going through a series of stages called instars. • Once fully matured, the larva develops into a pupa.
- 6. Pectinophora gossypiella (Saunders) The Pink Bollworm It is a serious pest of cotton
- 7. • Adult is a small moth having wingspan of 10- 15 mm, dark brown, with irregular black markings on the fore wing. Hind wing silvery gray with no distinct markings.
- 8. • Fecundity is about 150 eggs/female. • Eggs are flattened, pale yellow with striated surface and laid in the night on bracts, buds or flowers, singly or in small groups. • Incubation period is 4-6 days. • Larvae are pinkish in color with brownish head and 10 mm when full grown. • Then it penetrates the lint until it reaches the seed, which also it bores and damages.
- 10. • There are four larval instars and total larval development takes 20-30 days depending on temperature. • Larvae overwinter by curling inside cotton seeds and become active again in April. • Pupation takes place either in the lint or in debris or under bracts or bark on the plant. • Pupal period is 7-10 days and total life cycle is completed in 4-5 weeks
- 13. Cultural control: • Threshing and thoroughly burying all plant remains after cotton. • killing the larvae within seeds or lint bales by heating to about 60ºC. • Mass trapping with long-lived pheromone traps.
- 14. • Chemical control: Organophosphates were used in the past to control the pest • Genetically modified cotton: The use of modified Bt cotton, which expresses toxins from Bacillus thuringiensis (Bt), has reduced the need for pesticides.
- 15. Tryporyza incertulas The Yellow Stem borer
- 16. • This is primarily a pest of rice but also has been recorded to feed on maize and some wild grasses.
- 17. • Adults show sexual dimorphism. • Eggs are oval, flattened and whitish in colour. Incubation period of eggs is 5-8 days. • Larvae are pale yellow in colour with a brownish head, 20 mm long and bore into the stem near the node. • They usually feed on the lower part of the stem and migrate from one plant to another to mature. • There are 6 larval instars and larval development takes 20-27 days.
- 18. • Pupation takes place inside a whitish silken cocoon within the rice stem, near the root- stem joint. • Before pupation larva cuts an exit hole on the stem, above the surface of water and covers it with a silken web as an exit for emerge. • Pupal period is 9-10 days or longer in cold weather. Total life cycle takes about 45 days.
- 21. Damage • The larva feeds inside the stem and makes gallery causing dead heart in younger plants. The flowering plants show white head.
- 22. Control • Collection and destruction of egg masses and plants showing dead hearts helps to reduce pest population, particularly in nurseries. • Burning of stubbles or ploughing the field after harvesting is a good cultural practice. • Early or late planting is recommended in areas of heavy infestation.
- 23. • The following natural enemies keep the pest population under check : • Egg Parasites: Trichogramma sp. • Larval parasites: Amauromorpha accepta schoenobii; Isotima javensis. • Larval-pupal parasite: Trichomma sp.
- 24. Cnaphalocrocis medinalis Rice leafroller • The larvae are considered a pest on Oryza sativa and others.
- 25. • The moth is very active, bright yellow or straw in colour with two distinct wavy lines in the fore wing and one wavy distinct line in the hind wing.
- 26. • Eggs are laid singly or in groups arranged in longitudinal rows on the undersurface of the leaves which are scaly white in color. • Incubation period is 4–8 days. • 5–6 larval instars are found, larval period is about 22– 23 days. • It pupates with in the infested leaf fold for a period of 6–7 days. • The fully grown caterpillar is green in color and is 16.5mm long. • The total life cycle completed in about 5 weeks.
- 27. • Once protected in leaf roll , the larvae scrape and feed on the green tissues (the mesophyll layer) of the rice leaves, resulting in the appearance of linear, pale-white stripe damage.
- 29. Control • Host-Plant Resistance Several rice lines transformed with toxin genes from Bacillus thuringiensis (Bt) have been shown to be highly resistant to C. medinalis . • Cultural Control • Wider spacing and low usage of nitrogenous fertilizer decrease the percentage of leaf folder infestation. • Early planting may enable plants to escape a high degree of defoliation. • Chemical Control Many different kinds of insecticides including neem seed oil (Saxena et al., 1980) have been used for leaffolder control
- 30. • Biological Control • C. medinalis has a rich community of natural enemies in insecticide-free ricefields. • In China, Trichogramma japonicum and Apanteles cypris are the most important egg and early larval instar parasitoids. • In Sri Lanka, larval parasitization ranges from 38 to 70%. Five parasitoids (four hymenopterans and a tachinid) are quite common.
- 31. Rice Caseworm (Nymphula Depunctalis) • It is found in all the rice growing tracts of India and assumes serious proportions in certain season under swampy conditions.
- 32. • Tiny eggs are laid on leaves and leave sheath in rows and batches. • Under South Indian conditions a female lays about 150 eggs which hatch in about a week.
- 33. • Young larvae feed by scrapping the leave surface. • The larva makes a cylindrical, tubular case out of a portion of the leaf cut and remains inside it, moving with the case on the leaves. • It feeds on the leaves actively and becomes fully grown in about 20 days reaching a length of 10-12 mm.
- 35. • The larval stage pupates inside the last case. • Before pupation the case is attached to the leaf sheath above the water level and its both ends are plugged. • The pupal period lasts for about a week, after which it is converted into an adult insect. • The pest is active during the monsoon and there may be two or three broods in a season. • The life cycle is completed in about 35-40 days.
- 36. • The caterpillars can breathe in aquatic medium with the help of branched tubular gills, hence the pest infestation is found in the fields which are filled with water. • Dispersal of larvae takes place by floating on water. The case with larva drops in the water and it paddles to reach another plant.
- 37. Control • Cultural Method: • 1. Draining out the stagnant water from the field is very much effective in reducing the population of this pest. • 2. Rotation of crop is advisable. • 3. Destruction of weeds around the paddy fields (weeds acts as alternate host of this pest). • Chemical Method: • 1. Spraying with DDT or dusting the crop with 10% BHC or Carbaryl at the rate of 15-20 lbs/ acre is effective. • 2 Spraying of “К-oil” or any other insecticides on the water surface kill the caterpillars.
- 38. • Biological Method: • 1. Introduction of Elasmus sps; Apalteles sps; Bracon sps; Hormius sps is effective in controlling the destruction caused by the larvae because they paracitises the larval stages. • 2. Introduction of Pediobius sps and Apsilops sps is effective in controlling this pest because they parasitises the pupal stage.
- 39. • Snails are useful predators of eggs of the rice caseworm. The larvae are fed upon by the hydrophilid and dytiscid water beetles. Spiders, dragonflies, and birds eat the adults.
- 40. Rice Swarming Caterpillar (Spodoptera mauritia) • The adult is stoutly build dark-brown moth with a Bloch of white on the fore wing. The males are characterised by immense tuft of hairs on the fore legs.
- 41. • The female moth is nocturnal in habit and mate just 24 hours after their emergence. • The eggs are laid in batches on various kinds of wild grasses and paddy leaves. • The number of eggs laid per batch may be 200- 300.
- 42. • The fully grown larva is smooth, cylindrical and has a large pale colour with sub-dorsal and dorsal stripes. • The larvae feeds on rice leaves undergoes six instars and grows to a length of 3.8 cms. • It feeds during night and hides in soil in day time. Pupation takes place in soil in an earthen cocoon.
- 44. • Plants attacked by caterpillars have skeletonized leaves, shot holes, and dieback stems. Commonly the entire paddy crop dies within few days due to swarming attack.
- 45. • The caterpillar feed at night on the leaves and defoliates the plants completely. • Generally they invade the transplanted plots in large number in big swarm and devastate the whole plot overnight like cattle’s do. • After finishing the crop of one field the swarm marches to another field in a regular army formation manner, hence this pest is also called as “Army worm”.
- 46. Control Cultural Method: • 1. In case of severe attack of this pest, the entire area should be isolated by trenching and the crop should be ploughed up. Chemical Method: • 1. The field edges and bundh should be dusted with Gammexine (0.025 %) at the rate of 15 lbs/acre in early stages. • 2. Application of contact insecticide like BHC, Carbaryl or Methyl Parathione controls the caterpillars effectively.
- 47. Mechanical Method: • 1. Collection of caterpillars with a hand net or sweeping basket and their destruction. Biological Method: • 1. In the seedling stage, the nurseries may be flooded with water. This will bring up the caterpillars to the surface from where they will be picked up by predator birds. • 2. In small areas duck can be released in the field which feed upon the larvae of this pest.
- 48. • Adults can eliminated by introducing Bolas spiders to the fields. • This spider has the ability to spray a pheromone similar to female moth, to attract male moths. • Moths traps like wing traps and unitraps can also used to collect adults.