1. INTRODUCTION
1. Insect reach pest status when they are responsible for 5% loss of yield.
2. An insect is considered as a minor pest if it causes loss between 5-10%.
3. An insect is considered as a major pest if it causes loss more than 10%.
4. Expected crop losses due to insect pests in different crops:
Cotton-30%
Rice-25%
Maize, Sugarcane, Rapeseed-mustard-20%
Pulses, Groundnut, Other oilseeds-15%
Coarse cereals-10%
Wheat-5%
5. It is estimated that India loses approximately 18% of the crop yield due to pest attacks each year.
6. Of the losses due to various pests in India, insects contribute 26% of the total loss. 7. Monophagous pest: Phytophagous insects feeding on plants of one or few closely related species within a genus.
8. Oligophagous pest: Phytophagous insects feeding on plants of several genera within a family.
9. Polyphagous pest: Phytophagous insects feeding on plants of several families in various orders.
10. Planimeters are used to quantify defoliation.
RICE
11. Dead heart in young seedlings of rice and white ear head in panicle stage is symptom of damage of yellow stem borer, Scirpophaga incertulas.
12. Clipping of tips of rice nursery reduces the incidence of yellow stem borer and rice hispa.
13. Seedling root dip treatment with 0.02% chlorpyriphos gives protection against stem borer, gall midge and leaf hoppers.
14. Egg parasitoids, Trichogramma japonicum, Telenomus beneficiens is used for the control of yellow stem borer.
15. Silver shoot or onion leaf, a tubular gall in the place of normal shoot in rice is due to the attack of gall fly, Orseolia oryzae.
16. Over aged seedlings, late transplanting and climatic factors are favourable conditions for gall midge incidence.
17. Release of Platygaster oryzae parasitized galls @ 1/10 m² is recommended for the control of gall midge, Orseolia oryzae in rice.
18. Swarming caterpillar, Spodoptera mauritia cuts rice seedlings at night in large scale similar to cattle grazing.
19. Longitudinal folding of leaves and scrapping of green tissues in rice is due to the infestation of leaf folder, Cnaphalocrocis medinalis. 20. Rice leaf folder natural enemy is Xanthopimpla emaculata.
21. Application of super phosphate in rice reduces the incidence of rice leaf folder.
22. Circular patches of drying in rice field, drying and browning of young plants (hopper burn) is due to the attack of brown plant hopper, Nilaparvatha lugens (Delphacidae, Hemiptera)
23. Brown plant hopper, Nilaparvatha lugens is a vector of grassy stunt, ragged stunt and wilted stunt.
24. Wider spacing and formation of alleys in rice reduces brown plant hopper infestation. 25. Controlled irrigation by intermittent draining reduces brown plant hopper infestation.
26. Release of mirid bug, Cyrtorhinus lividipennis @ 100 bugs or 50-75 eggs/m² at 10 day interval was found effective for the control of BPH.
27. Spiders, Lycosa pseudoannulata and Marpisa pomatix are natural enemies in rice ecosystem. Presence of 3 predatory spiders/hill checked the population of BPH and white backed plant hopper.
28. Green leaf hopper, Nephotettix nigropictus is a vector of rice tungro, yellow dwarf, transitory yellowing and other viruses.
29. Dislodging the cases of case worm by pulling a rope in rice and draining water reduces case worm, Parapoynx stagnalis (=Nymphula depunctalis) infestation.
30. Gundi bug, Leptocorisa acuta emits obnoxious odour on disturbance. Hence the name. 31. Rolling and drying of leaf tips is due to the infestation of rice thrips, Stenchaetothrips biformis.
32. Chaffy grains in rice with a black spot is due to the attack of ear head bug, Leptocorisa acuta.
33. Black grains in the panicle, ill filled grains in rice, longitudinal purple patch on the ventral side of midrib of leaf is due to the attack of panicle mite, Steneotarsonemus spinki.
34. Paddy leaf mite, Oligonychus oryzae remain in large numbers in the lower surface of the leaves. White patches are seen due to desapping which later turns brown in colour.
35. White parallel streaks along the long axis of leaves show the infestation of rice hispa, Dicladispa armigera.
