Identification of Insect pests of sorghum and their symptoms

of damage

Dr. M. Thippaiah professor Dept. of Entomology College of Agriculture GKVK, UAS Bangalore- 65

Sorghum is a major crop in Maharastra, TN, AP, UP, Rajasthan, Haryana, Gujarat, Karnataka

In Karnataka – Major crop in Northern Karnataka i.e. Dharwad , Bijapur , Raichur, Bellary and in South grown in Chitradurga, Mysore ,Shivmoga

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

Borer pests of Sorghum

Sorghum shoot fly: Atherigona soccata (Muscidae : Diptera)

Adult fly

Maggot inside the shoot

Fully grown maggot

Adults resembles house fly, little smaller and grayish brown in colour with 6 black spots on the abdomen

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 daysLarvae : there are 4 larval instarsMaggots 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 %

6 black spots on the abdomen

Nature and symptoms of damage 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

Incidence - The 1-6 weeks old seedlings are more susceptible

In Karnataka – June – Sept. incidence will be more

The pest will complete its life cycle quickly at conditions like Temp – 25-300 c RH - more than 60% Continuous rain fall decrease pest incidence

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

Eggs are laid in clusters on the ventral surface of the leaves near the mid ribEach females lays – 225 eggsI.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

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

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

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

Ear head feeders

Jowar ear head bug : Calocoris angustatus (Miridae : Hemiptera)

It is a key pest of Sorghum in Southern states It attack the crop from ear head emergence to head dough stage, Yield loss- 54-89%

Adult is an active, slender yellowish green bug, measuring 5-8mm in length The bugs hover over the ear heads at the time of ear head formation Site of ovipositon: Eggs are laid in spikelet's on ear head

or under glumes or middle of the florets Each female lays - 100-200 eggs I.P – 5-7 days Nymphs: The nymphs pass 5 instars

Early instars light orange coloured and later changes to green colour or yellowish green in colour N.P – 15- 17 days, Two generations are noticed

It inflict severe damage to irrigated Sorghum during April – May and to less extent to rainfed Sorghum during Aug - Jan

Older grain shows distinct feeding punctures that reduce grain quality

Both nymphs and adults suck the milky juice from tender ear heads or developing grains, such grains shrink and turn black colour, thus make them turn chaffy or crinkled grains.

Older grain shows distinct feeding punctures that reduce grain quality

This bug has been recorded feeding on a number of Cereals, Millets and grasses, buts breeding is mainly restricted to sorghum

Symptoms of damage

Sorghum ear head midge : Contarinia sorghicola (Cecidomyiidae : Diptera)

Site of ovipostion:Eggs are laid in side the glumes of closed and open flowersEach female lays – 30 – 100 eggs I.P – 1-2 days

Maggots: are minute, pink, fleshy apodous L.P – 9-10 daysPupa : In side the damaged flowers or pupal cases are usually present at the tip of the glumes P.P – 5-6 days

Adults are fragile soft bodiedreddish mosquito like fly with

long legs and monili form antennaeand a pair of transparent wings and they have

long Telescopic ovipositor

Long telescopic ovipositor

Nature and Symptoms of damage Maggots on hatching feed on developing grains such infested ear heads become chaffy i.e. The larvae starts feeding on the ovaries and destroy developing grains results chaffy ear heads or partial filling of grains

partial filling of grains

chaffy ear heads

The affected spikelet's shrivel and fail to develop in to grains

Symptoms Red ooze from the spikelet when squeezed indicating the presence of Maggots Chaffy grains with round holes indicating fly emergence Empty pupal cases protruding from glumes

They have whitish pupal cases protruding out of the of the damaged spikelets

July sown crop – Severely affected Temp. - 25 – 300 C RH – 60% these factors encourage the pest population and also cloudy weather and intermittent rain fall increases the incidence

Ear head caterpillar: Helicoverpa armigera (Noctuidae :Lepidoptera)

The adult is a medium sized, light brown coloured moth Two prominent black spots on the fore wings Dull black border on the hind wings

When crop is at flowering stage we can find the adult moth activity

Symptoms of damage

Larva remains concealed in the inner branches of the ear and feed on the grains and damaged ears could be easily spotted in the field by their chalky appearance due to partially eaten grains

chaffy ear heads

Female moth lay eggs on inflorensce, the hatching caterpillar starts feeding on flowers till grain hardening stage

Caterpillar feed on the developing grains

Grass hopper feeds on the grains

Castor shoot and capsule borer: Conogethes punctiferalis ( Pyralidae : Lepidoptera)

Adult is a medium sized moth with small black dots on pale yellow wings

It attacks the plant at flowering stage and lays eggs on inflorensce and young caterpillar make webbings and feed on flowers and grains and they pupate with in the webbings

Chafer beetle : Oxycetonia spp. (Scarabaeidae : Coleoptera)

A light brown coloured beetle with white spots on the elytra Adults feeds on ear heads of sorghum and maize

Sap feeders

Shoot bug : Peregrinus maidis (Delphacidae : Hemiptera)

Adults are small, active ,light brown or dark brown in colour with transparent wings and movable spur on the hind legsThe brachypterous female is yellowish while macropterous female is yellowish brown and male dark brown in colour

Eggs are laid in groups of 1-4 inside the leaf tissue on midrib and covered with white Waxy substanceMaximum 97 eggs are laid by a female in life span of 7-10 daysThere are

5 nymphal instars

4-10 days16-18 days

7-10 daysTLC – 18-31 days

Damage Both nymphs and adults suck the sap from young leaves and leaf sheath resulting attacked plants become unhealthy, stunted growth and yellow patches

The leaves wither from top down wards and later turn reddish and finally attacked plants die in severe case.

honey dew secreted by the bug causes growth of sooty mould on the leaves

Vectors of viral diseases : 1. Sorghum stripe 2. Sorghum mosaic

Nymphs and Adults Attack plants reddish and finally such plants die in severe case

Aphids: Rhopalosiphum maidis ( Aphididae : Hemiptera )

Adults are dark bluish green and some what ovate .

It is 2mm long with black colored legs with cornicles on dorsal side of 5th and 6th abdominal segments

Winged and wingless forms are common

Corn leaf aphid Aphid damage Sugarcane aphid

cornicle

Nature of damage Nymphs and adults suck the sap from the leaves as a results yellowing of leaves, colonies of aphids in central leaf whorl, stem or panicles

The aphids produces an abundance of honey dew on which sooty moulds are grown

In panicles, honey dew may hinder harvesting

Presence of ants is the indication of attacked by aphids

The aphids also transmits Maize dwarf mosaic virus

Stink bug : Nezara viridula ( Pentatomidae : Hemiptera )

Adults are large green coloured bug with 5 segmented filiform antennae

Nymphs and adults suck the sap from the softer part of the plant but principally from the developing seeds The Injury is very negligible

Adults congregate onThe bajra ear head

Nymph is brownish red or dark brown with multicoloured spots

Defoliators

Colemania spheneroides (I. Bolivar) on sorghum It is endemic / cyclic pest in Northern Karnataka i.e in Haveri district and it appears once in 5 years

Deccan wingless grass hopper : Colemania sphenarioides ( Pyrgomorphidae : Orthoptra )

Adult is a medium sized, wingless grass hopper, measures 4-5 cm in length

Antennae short filiform

Body light green with pink and yellow stripes on lateral sides

Eggs : are laid in batches in the forms egg pod at 5 cm depth in soil in the month of Octo - Nov. and hatch in June - July

Symptom of damage

After monsoon showers the nymphs will come out and first feed on grasses and later take over to sorghum

They feed on leaves and also feed on flowers, ripening ear heads and all parts are eaten leaving only stalk

Army worm : Mythimna separata (Noctuidae : Lepidoptera)

It is serious in heavy rainfall areas

The adult is stout bodied, medium sized moth, greyish brown in colour

On the fore wings we find 2 white spots and prominent veins in the wings

Caterpillars

Pupae

Pale Brown coloured moth

Caterpillar feeds on leaf margin and mid rib and thus causing severe defoliation

Red headed hairy caterpillar: Amsacta alibistriga ( Arctiidae : Lepidoptera )

Caterpillars are reddish-brown in colour and hairy

Adults are medium sized mothsFore wings : are white with brown streak all over the wings and yellowish streak along the anterior marginHind wings : are white with black spots

Caterpillars are the voracious feeders of the foliage

They move from field to field in large swarms in search of suitable host plants thus causing large scale devastation of millet crops

Red hairy caterpillar

It is a polyphagous pest, often do considerable injury to young sorghum seedlings and caterpillars are the voracious feeders of the foliage

Sorghum leaf roller :Marasmia trapezalis ( Pyralidae : Lepidoptera)

Adult is a small, pale yellow brown coloured moth with black wavy markings on the wings Site of ovipostion : Eggs are laid singly on the upper leaf surface I.P – 4-5 days

Larva : there are 5 larval instars, pale brown with reddish brown head and brown prothorax L.P – 15-20 daysPupa : Pupation takes place with in leaf fold, P.P – 7-8 days

Symptoms of damage The larva folds or roll the leaves and feeds on the green matter Longitudinal patches on leaves with drying tips Broad leaf varieties are more susceptible for this pest

Jowar flea beetle : 1. Chaetocnema sp. (Chrysomelidae : Coleoptera )

Black shinning beetle and very active, jump when slightly touched with enlarged hind femora It is often serious in seedlings of summer and rabi sown crop Adults feeds on leaves and pin holes observed on leaves

2. Monolepta signata ( Chrysomelidae : Coleoptera )

Adult is a black coloured beetle with long antennae and four pale yellow spots on the elytra

Adults feeds on the leaves make holes on the leaves

Non insect pest

Jowar mite : Oligonychus indicus ( Tetranychidae : Acarina)

Both nymphs and adults suck the sap from the leaves as a results infested areas become pale yellow but later turn to reddening of tissues on dorsal side which coalesce and entire leaf red in colour and dry up

The plant growth and grain development is affected

Webbing can be seen on the undersurface of the leaf

These are microscopic, greenish yellow oval shaped mites and they found on ventral surface in colonies, they forms webs

Nymphs are pale yellow in colour