The major insect pests of groundnut, their nature of damage and appropriate control measures are given below:
1. Red Hairy Caterpillars (Amsacta albistriga, A. moorei):
Nature of Damage:
Caterpillars cause defoliation of the crop- all the leaves eaten away leaving the main stem alone.
Identification:
Hairy caterpillar reddish brown with black band on either end having long reddish brown hairs all over the body. Adult moth with white wings. Fore wing white with brownish streak all over and yellowish streak along the anterior margin and head Hind wing are white with black marking Forewing are white with brownish streak all over and reddish streak along the anterior margin and head.
Management:
Deep summer ploughing. Early sowing is done to escape insect pest damage. Inter crop one row of castor for every 5 or 6 rows of groundnut. Crop rotation with sorghum/pearl millet or maize should be followed. Vegetative traps utilizing Jatropa (wild castor) or Ipomoea prevent the migration of the grown up larvae. Irrigate once to avoid prolonged mid-season drought to prevent pre-harvest infestation. Install 12 light traps/ha or bonfire in endemic areas.
Collecting and killing of adult moths are found very effective. Collection and destruction of egg masses in the fields around light trap areas. Install 10-12 bird perches/ha. Two hand or mechanical weeding should be done at 15-20 days after sowing. Spray A-NPV (2X 10^5 PIB/l) or Bacillus thuringiensis (Bt). Release Bracon hebetor @ 5000/ha twice at 7-10 days interval. Conserve dominant predators like Coccinella sp. and Menochilus sexmaculata and parasitoids like Chelonus spp.
Conserve the bio control population of spiders, long horned grasshoppers, preying mantids, robber fly, ants, green lace wing, damsel flies/dragon flies, flower bugs, shield bugs, lady bird beetles, ground beetle, predatory cricket, braconids, trichogrammatids, NPV, green muscardine fungus.
Inter cropping with pigeon pea, mung bean and soybean provides increase in population of spiders. Population of coccinellids is higher on groundnut with maize, mung bean and soybean and Chrysoperla spp. is higher with maize and soybean intercrops. Spray endosulfan 35 EC or quinalphos 25 EC @ 1250 ml/ha or 500 ml of nuvan (76%) 4 ml/ha to control full grown insects.
2. Groundnut Leaf Miner (Aproaerema modicella):
Nature of Damage:
Young larvae initially mine into the leaflets, feed on the mesophyll and form small brown blotches on the leaf. Later stages larvae web the leaflets together and feed on them, remaining within the folds. Severely attacked field looks “burnt” from a distance.
Identification:
Eggs are shiny white and are laid singly on the underside of the leaflets. Larvae – Green in colour with dark head and prothroax. Adults are brownish grey moth, 6 mm long with 10 mm wing span. Forewings with white spot on the costal margin.
Management:
Stray planting of cowpea or soybean as trap crop. Crop rotation with non-leguminous crop is advised in case of severe recurring problem. Crop rotation of groundnut with soybean and other leguminous crops should be avoided. Collect and destroy egg masses and early instars larvae. Install light trap @ 12/ha for mass trapping.
Release Trichogramma Chilonis @ 50000/ha twice (7-10 days interval). Conserve the bio control population of spiders, long homed grasshoppers, preying mantids, robber fly, ants, green lace wing, damsel flies/dragon flies, flower bugs, shield bugs, lady bird beetles, ground beetle, predatory cricket, braconids, trichogrammatids, NPV, green muscardine fungus.
Mulching with rice straw causes reduction in leaf miner incidence and increase the percentage parasitisation. Intercropping groundnut with Pennisetum glacum enhances the parasitisation Goniozus spp. on leaf miner. Effective control could be achieved if insecticide is applied at 45 and 70 days after planting. Spray quinalphos 25 EC 2ml or methyldemeton 25 EC 1.6ml or dimethoate 30 EC 2ml per litre of water.
3. Bihar Hairy Caterpillar (Spilosoma (Diacrisia) oblique):
Nature of Damage:
Young larvae feed gregariously mostly on the under surface of the leaves. Feed on leaves and cause loss by way of defoliation. In severe cases only stems are left behind.
Identification:
Eggs laid in clusters of 50-100, on the lower side of leaves. Larva orange coloured with broad transverse band with tufts of yellow hairs that are dark at both ends Pupa forms a thin silken cocoon by interwoven shed hairs of the larvae. Adults are crimson coloured moth with black dots and a red abdomen. Pinkish wings with numerous black spots.
Management:
Pre-monsoon deep ploughing (two/three times) will expose the hibernating pupae to sunlight and predatory birds. Removal and destruction of alternate wild hosts (weeds) which harbour the hairy caterpillars. Grow trap crops like cowpea, castor and jatropha on field bunds to attract the caterpillars.
Irrigate once to avoid prolonged mid-season drought to prevent pre-harvest infestation. Setting up bonfires on field bunds during night. Mass collection and destruction of eggs and just emerged caterpillars. Place the twigs and leaves of calotropis, jatropha and papaya around the field to trap grown up caterpillars and destruction.
Conserve the bio control population of spiders, long horned grasshoppers, preying mantids, robber fly, ants, green lace wing, damsel flies/dragon flies, flower bugs, shield bugs, lady bird beetles, ground beetle, predatory cricket, braconids, trichogrammatids, NPV, green muscardine fungus.
Use of NPV (nuclear polyhedrosis virus) on cloudy days at 500 LE/na will be effective. Spraying of Bacillus thuringiensis is also advocated at 1 kg/ha where mulberry is not grown. Apply safe chemical insecticides at recommended doses only if the insect population crosses the ETL. Spraying of quinalphos 25 EC (2 ml/lit) or chlorpyriphos 20 EC (2.5 ml/ lit) or endosulfan 35 EC (2.0 ml/lit) recommended when the caterpillars are younger.
4. Gram Pod Borer (Helicoverpa armigera):
Nature of Damage:
Larvae feed on the foliage, prefers flowers and buds. When tender leaf buds are eaten symmetrical holes or cuttings can be seen upon unfolding of leaflets.
Identification:
Eggs are spherical in shape and creamy white in colour, present singly. Larva shows colour variation from greenish to brown. It has dark brown grey lines on the body with lateral white lines and also has dark and pale bands. Pupa are brown in colour, occurs in soil, leaf, pod and crop debris. Adult light pale brownish yellow stout moth. Forewings olive green to pale brown with a dark brown circular spot in the centre Hind wings are pale smoky white with a broad blackish outer margin.
Management:
Deep summer ploughing. Intercrop one rows of red gram for every 5 or 6 rows. Install pheromone trap @ 5/ha. Use Trichogramma chilonis @ 1 lakh/ha or Chrysoperla carnea @ 50000/ha at 40 and 50 days after sowing of groundnut can effectively check the pest.
Conserve the bio control population of spiders, long horned grasshoppers, preying mantids, robber fly, ants, green lace wing, damsel flies/dragon flies, flower bugs, shield bugs, lady bird beetles, ground beetle, predatory cricket, braconids, trichogrammatids, NPV, green muscardine fungus. Spray quinolphos 2ml or chloropyriphos 3ml or endosulfan 2ml /lit of water.
5. Tobacco Caterpillar (Spodoptera litura):
Nature of Damage:
Freshly hatched larvae feed gregariously, scraping the chlorophyll, soon disperse. Sometimes the feeding is so heavy that only petioles and branches are left behind.
Identification:
Egg masses appear golden brown. Larva pale greenish with dark marking. Gregarious in the early stages Adult forewings are brown colour with wavy white marking. Hind wings are white colour with a brown patch along the margin.
Management:
Deep summer ploughing. Early sowing to escape insect pest damage. Irrigate once to avoid prolonged mid-season drought. Planting castor or sunflower plants as trap crop for egg laying and destroying eggs or first instars larvae help in reducing the incidence. The sunflower act as bird perches as well. Install light trap. Two hand or mechanical weeding at 15-20 days after sowing.
Use pheromone traps (5/ha) to monitor moth population. Install 10-12 bird perches per ha. Collection of egg masses/early instars larvae from trap crops. Release of Telenomus remus @ 50000/ha. 4 times (7-10 days interval) based on pheromone trap catching. Release Trichogramma chilonis @ 50000/ha twice (7-10 days interval) based on pheromone trap observation.
Spray insect pathogenic fungus Nomuraea rileyi @1013 spores/ha for controlling early instars. Apply Methyl parathion 2% dust @ 20 kg/ha or spraying of monochrotophos 36 SL or quinolphos 25 EC @ 1500 ml or endosulfan 35 EC @1250 ml or trizophos 40EC @ 800 ml in 700-800 lit of water. Poison bait with monocrotophos 36 SL or carbaryl, rice bran, jaggery and water can be used to control the grown up larvae.
6. Aphids (Aphis craccivora):
Nature of Damage:
Wilting of tender shoots during hot weather. Stunting and distortion of the foliage and stems. They excrete honeydew on which sooty molds flow forming a black coating. Act as vector for peanut stripe virus and groundnut rosette virus complex.
Identification:
Nymphs & Adult are reddish to dark brown coloured with cornicles in the abdomen.
Management:
Timely sowing of the crop. Hand picking and destruction of various insect stages and the affected plant parts. Augment the release of Menochilus sexmaculata @ 1250/ha. Conserve bio agents like flower bugs (anthocorids), lady bird beetles (coccinellids), praying mantids, hover flies (syrphids), green lace wing (chrysopids), long homed grass hoppers and spiders.
Young crop may be applied with monochrotophos 36 WSL 600ml/ha or dimethoate 30 EC @ 650 ml/ha in 600 liter water. Dusting of endosulfan 4% dust at 1 kg a.i. /ha would be effective in controlling aphids.
7. Jassids (Empoasca kerri):
Nature of Damage:
Nymphs and adults inject toxins resulting in whitening of veins and chlorotic patches especially at the tips of leaflets, in a typical ‘V’ shape. Heavily attacked crop looks yellow and gives a scorched appearance known as ‘hopper burn’.
Identification:
Adult are elongate, active, wedge shape, green insects.
Management:
Timely sowing of the crop and field sanitation. Crop rotation with non-host crop. Intercropping with pearl millet. Avoid groundnut-castor inter crop, it increases the infestation. Irrigate once to avoid prolonged mid-season drought to prevent pre-harvest. Spray dimethoate 30EC @ 650ml/ha or monochrotophos 36WSC @ 600ml/ha in 600 liter water.
8. Thrips (Scirtothrips dorsalis):
Nature of Damage:
Tender leaves showing yellowish green patches on the upper surface and brown necrotic areas and silvery sheen on the lower surface. Severe infestations cause stunted plants.
Identification:
Nymphs – Yellowish. Adults are dark coloured with fringed wings.
Management:
Spray monochrotophos 36 WSC 600 ml/ha or dimethoate 30 EC 650 ml/ha or methyldemeton 25 EC 600 ml in 600 lit of water. Spray per acre monocrotophos 320ml mixed with neem oil 1 liter and 1 kg soap powder mixed in 200 liter of water twice at 10 days interval.
9. Jewel Beetle (Sphenoptera indica):
Nature of Damage:
Wilting of plants in patches. The grub burrows into the stem close to the soil surface and kills the plant. Infested fields show dead and dying plants, which when pulled up and examined grub/pupa can be seen in hollowed stem.
Identification:
Larvae slow movers having globular head and elongated, dorso-ventrally flattened body. Adult are shiny beetle, 10 mm long and 3 mm wide.
Management:
Deep ploughing in the summer. Use well decomposed organic manure. Manual destruction of infested plant stems may help in reducing its population. Conserve braconids, dragon flies, trichogrammatids, NPV, green muscardine fungus. Applying carbofuran granules@ 2.25 kg a.i/ha in the planting row can be effective prophylactic measure.
10. Termites (Odontotermes sp.):
Nature of Damage:
Wilting of plants in patches. Termites penetrate and hollow out the tap root and stem thus kill the plant. Bore holes into pods and damage the seed. It removes the soft corky tissue from between the veins of pods causing scarification, weaken the shells, make them liable to entry and growth of Aspergillus flavus that produces aflotoxins.
Identification:
The termites are endemic in red and sandy soils. These are social insects, live in termataria, in distinct castes, workers, king and queen. Workers’ are small (4 mm) and have a soft, white body and a brown head.
Management:
Digging the termataria and destruction of the queen is most important in termite management. Use well rotten organic manure. Harvest the groundnut as soon as they are matured, early removal of the produce from the field will reduce the chances of termite damage to pods. Clean cultivation Irrigate the crop frequently.
Thorough ploughing and frequent intercultural operations reduces termite damage. Destruction of debris, termite nests and queen. Apply chlorpyriphos 20 EC or lindane 1.3% to control termites. Dust chlorpyriphos @ 30-40 kg/ha in soil before sowing in endemic areas. Seed treatment with chlorpyriphos @ 6.5ml Ag of seed may reduce termite damage.
11. White Grubs (Holotrichia consanguinea, H. serrata):
Nature of Damage:
The grubs feed roots and damage pods. Grubs feed on fine rootlets, resulting in pale wilted plants, dying in patches.
Identification:
Eggs are white, almost round. Young grubs are translucent, whitish yellow in colour, fleshy ‘C’ shaped. Adults are dark brown beetle. Beetles emerge out of the soil within 3-4 days after the onset of rain.
Management:
Deep ploughing in summer. Always use well decomposed organic manure it attracts the adult beetles. Partial or complete lopping of host plants and retaining of a few most preferred host trees in the area for congregation of white grub adults. Crop rotation with sorghum/pearl millet or maize. Early sowing to avoid damage due to insect pest. Collection and destruction of white grub adults from host trees around the field.
Spray should be undertaken as a community approach and should be repeated after every rainfall till the middle of July. Spraying the neem trees close to the field with chlorpyriphos 20 EC @ 2 ml/lit of water soon after first monsoon showers for 3-4 days in the late evening hours kills the adult beetles and reduces root grub infestation. Seed treatment with chlorpyriphos 20 EC (6.5 to 12.5 ml/kg seed) is found to be effective. In case of severe infestation apply phorate @ 10 kg/ha.
12. Pod Borer (Anisolabis stalli):
Symptoms of Damage:
Young pods showing bore holes plugged with excreta. Sand particles or discoloured pulps. Pods without kernal.
Identification:
Nymphs are white in early stages and later turns brown. Adult are dark brown to black with forceps like caudal cerci and white leg joints.
Management:
Apply malathion 5 D 25 kg/ha or endosulfan 4 D 25 kg/ha to the soil prior to sowing in endemic areas. Repeat soil application of any one of the above dust formulations on the 40th day of sowing and incorporate in the soil during the earthing up.
13. Pod bug [Elasmolomus (Aphanus) sordidus]:
Nature of Damage:
Freshly harvested pods having shriveled kernels.
Identification:
Nymph – Pinkish and adult are dark brown bugs.
Management:
Apply malathion 5 D @ 25 kg/ha or endosulfan 4 D @25 kg/ha to the soil prior to sowing in endemic areas. Repeat soil application of any one of the above dust formulations on the 40th day of sowing and incorporate in the soil at the time of earthing up.