Insect pests of sorghum and maize

Insect pests of sorghum and maize

1. Insect pests of Sorghum & Maize and their management Course N o . AENT – 5312 Course Title – Pests of crop and stored grain and their management Prepared by, Navneet Mahant Dept. of Agril . Entomology BHARTIYA COLLEGE OF AGRICULTURE, PULGAON, DURG (C.G) – 491001 Affiliated to Indira Gandhi Krishi Vishwavidyalaya , Raipur (C.G)

2. Sorghum is a major crop in Maharastra, TN, AP, UP, Rajasthan, Haryana, Gujarat, Karnataka , MP,Chhattsgarh More than 150 species of Insects have been reported to damage Sorghum. However, over a dozen species are very serious and constitute a major constraint in sorghum production These insect pests are classified as Borer pests Ear head feeders Sap feeders Defoliators Non insect pests

3. Borer pests of Sorghum Sorghum shoot fly Sorghum stem borer Ear head feeders pests of Sorghum Jowar ear head bug Sorghum ear head midge Ear head caterpillar Chafer beetle

4. Sap feeders of Sorghum Shoot bug Aphids Stink bug D e f oli a t o r s Army worm grass hopper Jowar flea beetle Red hairy caterpillar

5. Sorghum shoot fly: Atherigona soccata (Muscidae : Diptera) Adult fly Maggot inside the shoot Fully grown maggot Eggs: are laid on 2 to 5 youngest leaves of sorghum seedlings Among this it prefers the basal half portion of ventral surface of leaves I.P: 1 to 2 days Larvae : there are 4 larval instars Maggots are apodous and yellowish in colour and tapering to wards anteriorly L.P : 6 to 12 days Pupa : pupation at base of the stem. PP – 6 to 8 days Life stages of the pest It is a major pest in all traditional sorghum growing areas like Maharashtra, TN, and Karnataka Alternate hosts – Maize, Ragi, Wheat, Bajra More incidence observed in late kharif and early rabi crop While Insects cause 12 % loss in Sorghum Production Shoot fly alone is responsible for 5 % Adults resembles house fly, little smaller and grayish brown in colour with 6 black spots on the abdomen

6. 6 black spots on the abdomen

7. Nature and symptoms of damage Incidence - The 1-6 weeks old seedlings are more susceptibl e Maggots on hatching crawls on upper surface of the leaf and later, penetrate / enter between leaf sheath and stem and further maggot reaches ground level and feed on growing point between leaf sheath and leaf whorl as a result in wilting and drying of central shoot know as ‘ dead heart ‘ symptoms. Growing point soft, succulent protected by leaf sheath and starts decaying which is fed by maggots, the central shoot dies and more tillers will come out the maggots will affect these side shoots and when dead hearts are pulled out they come up easily and produce bad smell Dead heart ‘ symptom The pest will complete its life cycle quickly at conditions like Temp – 25-30 c RH - more than 60% Continuous rain fall decrease pest incidence

8. Management Take up early sowing of sorghum immediately after the receipt of South West or North East monsoon to minimise the shoot fly incidence. Use seeds pelleted with insecticides Seed treatment with imidacloprid 70 WS @ 10 g/kg of seeds In case of direct seeding, use increased seed rate upto 12.5 kg/per hectare and remove the shoot fly damaged seedlings at the time of thinning or raise nursery and transplant only healthy seedlings . Plough soon after harvest, remove and destroy the stubbles. Spray one of the following for an area of 120 m2 nursery : Methyl demeton 25 EC 12 ml/ha Dimethoate 30 EC 12 ml/ha In main field for direct sown crop spray any one of the following Methyl demeton 25 EC 500 ml/ha Dimethoate 30 EC 500 ml/ha Neem Seed Kernel extract 5%

9. Sorghum stem borer: Chilo partellus ( pyralidae : Lepidoptera) Adult is a medium sized, straw coloured moth or light brown coloured moth, 2cm across the wing Fore wings are light brownish / yellowish with row of black dots on the apical margin or outer margin Hind wings are whitish in colour in females and straw coloured in males

10. E ggs are laid in clusters on the ventral surface of the leaves near the mid rib Each females lays – 225 eggs I.P- 2-5 days Larva passes 5-6 instars, the larva yellowish brown with reddish brown head and prothoracic shield and measures 25mmlong with series of black dots L.P-28-35 days It pupate inside the stem in a small chamber P.P- 8-15 days TLC- 30-40 days

11. Nature and symptoms of damage Larva is damaging stage The larvae bores into mid rib and the shoot and feeds on the internal tissues and causes typical ‘dead heart’ formation, thus killing young plants In the early stage – hatching larvae feed on the surface of leaf sheath and leaf whorls causing pin holes / shot holes on the whorls of newly opened leaves As the severity of leaf damage increases , blend of feeding punctures and scratches appears on leaves The infestation starts 20 days after seedling emergence and continued till maturity

12. After the inter node elongation the growing point moved up wards , the larvae make tunnel in to the stem and also presence of red patches on the inter nodal region Later infestation occurs on the top portion of the stem Both stem and peduncle are damaged by the larva leads to production of complete chaffy ear head or partial chaffy ear heads The infested peduncle may also break down Bored hole on the stem Presence of red patches on the inter nodal region

13. Larvae in side the stem Symptoms Mid rib tunneling by early instar larva A series of pin holes on emerging leaves In young plants the pest causes a typical dead hearts In older plants the upper part of the stem usually dies due to boring of the caterpillars in the stem pith

14. Management ETL:  10% damage Sowing the lab lab / cowpea as an intercrop to minimise stemborer damage (Sorghum: Lab lab / cowpea). Set up of light traps till mid night to monitor, attract and kill adults of stem borer, grain midge and earhead caterpillars Mix any one of the following insecticides with sand to make up a total quantity of 50 kg/ha and apply in the leaf whorls : Phorate 10 G 8 kg/ha Carbofuran 3 G 17 kg/ha Spray any one of the following insecticides : Carbaryl 50 WP 1.00 kg/ha (500 l spray fluid/ ha ).