Rice Plant- and Leaf Hoppers

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Identification, symptoms and nature of damage of
Gundhi bug, Thrips and Armyworm
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Introduction

• Rice (Oryza sativa L.) is the staple food crop
  of humid and sub-humid Asia, cultivated in 112
  countries covering every continent and is
  consumed by 2500 million people in the developing
  countries. Rice is grown on an area of 44.3
  million hectares in different agro-climatic
  regions of the country with a production of 89.09
  million tonnes. However, Indias productivity is
  much lower than neighbouring countries.

• Damage by several insect pests is one of the
  major factors responsible for lower rice yields.
  Intensive cultivation of rice has aggravated the
  problems of various biotic constraints like
  insects, diseases, and weeds.

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• Rice gundhi bug, thrips and armyworm are
  important pests of rice and inflict heavy yield
  losses during certain years. Their effective
  management thus becomes essential to ensure good
  harvest to the farmers.

Pest problem being discussed with farmer
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1. Gundhi bug (Leptocorisa acuta)

• Identification

• Gundhi bug adults are slender yellowish green
  bugs with long antennae and legs.

• Nymphs resemble adults except for presence of
  wings. These bugs produce typical dirty smell in
  the field and hence this pest is known as gundhi
  bug. The smell helps in detecting presence of
  this pest in the field.

Gundhi bug adult
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Nature of Damage

• Female lays several dark brownish eggs in long
  rows on underside the leaves.

Gundhi bug eggs

• Both nymphs and adults suck juice from developing
  grains during milky stage of the crop.

• The affected grains remain chaffy and black spot
  develops on them due to fungal infection at the
  point of puncture. Under severe infestation
  several empty grains can be found in affected
  panicles.

Gundhi bug Nymph
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Staggered planting intensifies its incidence in
an area as bugs get grains in milky stage for
longer period of time and they migrate from field
to field.

• Sawan grass (Echinochloa) weed is its alternate
  host plant and it should be destroyed in order to
  reduce incidence of this pest.
• Economic threshold level
• 1 bug/hill

Echinochloa (Sawan grass) Alternate host plant of
gundhi bug
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2. Thrips (Stenctenchaetothrips biformis)
Identification

• Thrips are minute thin black-brown insects which
  jump on disturbance. These can be found by
  removing the leaf sheath at its junction with
  stem.

Rice thrips- adult Courtesy agritech.tnau.ac.in

• Both nymphs and adults damage the crop during
  seedling stage in the nursery as well in the main
  field.

• They suck sap from leaves resulting in yellowish
  streaks on them. Later, the leaves curl
  longitudinally from margins inwards leading to
  sharply pointed leaf tips resembling needles.

Rice thrips-Nymph Courtesy agritech.tnau.ac.in
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• Infestation at panicle stage causes unfilled
  grains or spikelet sterility. Sometimes, complete
  panicle remain chaffy and are confused with
  white-ear damage of the stem borer.

• However, thrips damage can be differentiated from
  that of stem borer damage in the sense that while
  white-ears can be easily pulled out but panicles
  affected by thrips can not be removed with that
  ease. Besides, panicles damaged by thrips have
  some black spot at their puncture points.

Silvery streaks on rice leaves caused by thrips
Courtesy agritech.tnau .ac.in
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3. Armyworm (Mythimna separata)
Identification

• The armyworm, also called climbing cutworm or
  ear-cutting caterpillar, was named so because of
  larvaes habit of appearing in army-like enormous
  numbers.

• Adults are dirty brown stout moths and larvae are
  also brownish in colour.

Armyworm adult
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Nature of Damage

• Only larvae damage the crop. Though sporadic in
  occurrence, this pest may cause heavy losses
  during sudden outbreaks.

• Larvae are nocturnal in nature and hide in loose
  soil, under trash, in stubbles and in whorls
  during day time. During night they become active
  and feed on foliage.

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• When high populations occur, army of swarming
  larvae march in the field and feed voraciously
  on leaves.

• Absence of standing water in the field
  facilitates their migration. Severely attacked
  field gives a grazed appearance. The larvae cut
  the ear-heads in addition to damaging the
  foliage.

• Economic threshold level (ETL)
• 1 larva/hill

Armyworm larva
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Let us sum up

• Gundhi bugs produce typical foul smell in the
  field and hence this pest is known as gundhi
  bug.

• Both nymphs and adults of gundhi bug suck juice
  from developing grains during milky stage of the
  crop.

• Echinochloa weed is alternate host plant of
  gundhi bug and it should be destroyed in order to
  reduce incidence of this pest.

• Both nymphs and adults of thrips suck sap from
  leaves causing yellowish streaks on them. Later,
  the leaves curl longitudinally from margins
  inwards leading to sharply pointed leaf tips
  resembling needles.

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• Panicles damaged by thrips have black spots at
  their puncture points.

• The armyworm, also called climbing cutworm or
  ear-cutting caterpillar, is named so because of
  larvaes habit of appearing in army-like enormous
  numbers.

• Absence of standing water in the field
  facilitates migration of armyworms. Severely
  attacked field gives a grazed appearance.

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