Title: Rice Plant- and Leaf Hoppers
1Identification, symptoms and nature of damage of
Gundhi bug, Thrips and Armyworm
2Introduction
- 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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3- 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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41. Gundhi bug (Leptocorisa acuta)
- 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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5Nature 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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6Staggered 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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72. 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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8- 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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93. 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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10Nature 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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11- 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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12Let 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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13- 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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