priciples of insecticide use in rice ipm

Insecticides in Rice IPM (DRR)
Cut worms Mythimna separata (Walker) and army worms Spodoptera mauritia (Boisd.)
These are a group of noctuid pests occurring sporadically in rice. The most
important among these insects are (1) the army worm Spodoptera mauritia
and the cut worm Mythimna separata. The former is a gregarious pest. It
used to cause severe losses to rice crop before the green revolution era.
This pest moves from one field to another field in large numbers like an army
Cut worm Larva
and almost completely defoliates the rice crop in the fields they invade. Hence,
the name army worm. Cut worms, at times become serious and feed on the foliage during initial stages of
crop growth. After flowering, the larvae climb and cut the ear-heads resulting in falling of the entire ear
head or a part of the ear-head. This results in very serious losses to the crop. The infestation may occur
just before harvest leading to falling of even matured grains in huge quantities.
Mealy bug Brevennia rehi (Lindinger)
Mealy bug damage & adult (inset)
Rice thrips Stenchaetothrips biformis (Bagnall)
Mealy bug is a common pest in upland and dry areas and in fields with
uneven surface and where plant stand is not uniform and patchy.
These mealy bugs are covered by a distinct waxy and powdery coating.
Ants frequently visit the mealy bug infested plants and help in the
dispersal of bugs from one plant to another. Both the adults and
nymphs suck the plant sap resulting in the stunted growth and curved
yellowish leaves. In severe infestations, plants dry up and panicles do
not emerge from the boot leaf. Damage occurs in patches and is
severe under moisture stress conditions.
Rice thrips (S. biformis) occur during the seedling stage and in early transplanted crop. The nymphs and
adults suck the sap from the leaves. Due to this feeding, initially yellow streaks appear on the leaves and
Thrips Thrips Damage
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