Rice is the principal staple crop of Nagaland and is cultivated under jhum, terrace, and wetland ecosystems. The warm and humid climate, coupled with high rainfall, favours the incidence of several insect pests that can significantly reduce yield if not managed properly. Integrated Pest Management (IPM) which combines cultural, mechanical, biological, and need-based chemical control measures can be adopted to manage pests economically while minimizing environmental impact. Major insect pests and their managements are given below
1. Yellow Stem Borer (Scirpophaga incertulas )
Damage Symptoms
• Larvae bore into the stem and feed internally.
• Causes dead hearts during the vegetative stage. Produces white ear heads during the reproductive stage.
• Heavy infestation results in severe yield loss
IPM Practices
• Use healthy, pest-free seedlings. Clip seedling leaf tips before transplanting to remove egg masses.
• Synchronize planting within the locality.
• Rice varieties with short stature and shorter growth duration periods suffer less damage than long growth duration varieties.
• Maintain balanced fertilizer application; avoid excessive nitrogen.
• Planting or seeding times may be delayed to avoid the peak emergence of moths from the diapausing populations.
• Collect and destroy egg masses.
• Conserve natural enemies and Install pheromone traps (10–12 traps/ha) for monitoring the pests
• Trichogramma japonicum and T chilonis may be released @ 1 lakh/ha on appearance of egg masses or moth of yellow stem borer.
• Apply recommended insecticides only when the economic threshold level (ETL) is reached.
2. Rice Leaf Folder (Cnaphalocrocis medinalis)
Damage Symptoms
• Larvae fold leaves and feed inside.
• White longitudinal streaks appear on leaves.
• Severe infestation reduces photosynthesis and grain filling.
IPM Practices
• Early planting may help to avoid greater degrees of leaf damage.
• Remove grassy weeds around the fields.
• Wider spacing (22.5 x 20 cm and 30 x 20 cm) and low usage of nitrogenous fertilizers decreases leaf damage.
• Encourage predators such as spiders, cricket and parasitoids.
• Higher damages will occur in shaded areas. Therefore, remove the causes of shading within the field.
• Install light traps for monitoring adult moths.
• On appearance of egg masses or moth of leaf folder release Trichogramma chilonis @ 1 lakh/ha
• Use insecticides only if infestation exceeds ETL.
3. Brown Plant hopper (BPH) (Nilaparvata lugens)
Damage Symptoms
• Nymphs and adults suck sap from the base of rice plants.
• Leaves turn yellow and dry.
• Severe infestation causes hopper burn.
• Also transmits viral diseases.
IPM Practices
• Avoid excessive nitrogen application.
• Maintain proper plant spacing and field sanitation.
• Drain fields temporarily during heavy infestation. Field should be drained for 3-4 days when heavy infestation occurs.
• Using early maturing varieties reduces plant hopper abundance and damage.
• Conserve natural enemies such as spiders, mirid bugs, and ladybird beetles.
• Avoid indiscriminate spraying of broad-spectrum insecticides.
• Synchronous planting (planting neighbouring fields within 3 weeks) and maintaining a paddy free period may be effective
• Apply recommended insecticides only when ETL is exceeded.
4. Rice Hispa (Dicladispa armigera)
Damage Symptoms
• Adults scrape green tissues, producing white streaks.
• Larvae mine inside leaves.
• Severe infestation dries leaves and reduces plant vigour.
IPM Practices
• Clipping and destruction of the top three-fourths of the leaves of highly infested crops with eggs and grubs at the early vegetative stage can suppress populations.
• Maintain field sanitation.
• Avoid delayed planting and encourage natural enemies.
• Removal of rice ratoons and volunteer rice during the crop-free season affects the rice hispa’s survival and multiplication of over-wintering populations.
• In situations of high hispa incidence, skip nitrogen fertilizer top-dressing. (Note that top- dressing after the pest is controlled can enhance recovery)
• Apply need-based insecticide if infestation becomes severe.
5. Rice Gundhi Bug (Leptocorisa acuta)
Damage Symptoms
• Adults and nymphs suck sap from developing grains.
• Grains become chaffy or partially filled.
• Infested grains produce a characteristic unpleasant odour.
IPM Practices
• Keep field bunds free from weeds.
• Synchronize planting to avoid prolonged flowering.
• Conserve predators such as spiders, dragonflies and tiger beetles.
• Use sweep nets or hand collection during early morning.
• Install light traps for monitoring.
• Install Stench Trapping during milky stage: Place dead frogs, rotten crabs, or pieces of jackfruit on bamboo sticks across the paddy field. The strong odour acts as a powerful attractant, luring the bugs away from the developing grains.
• Light & Smoke Traps: Light fires (bonfires) or use hollow bamboo torches in the four corners of the field during evening hours to attract the bugs.
• Spray insecticides only during severe infestation at the milky stage.
ETL Level at different crop growth stages
Pests | Nursery | Planting to Pre-tillering | Mid-tillering | Panicle Initiation to Booting | Flowering and after |
YSB | 1 moth or 1 egg mass/ m2 | 5% dead heart or 1 moth or 1 egg mass/ m2 | 5% dead heart or 1 moth or 1 egg mass/ m2 | 5% dead heart or 1 moth or 1 egg mass/ m2 | - |
Leaf Folder | - | 1 freshly damaged leaf/ hill or 10% damaged leaves | 1-2 freshly damaged leaves/ hill | 1-2 freshly damaged leaves/ hill or 10% damaged leaves | - |
BPH | - | 5-10 insects/ hill | 5-10 insects/ hill | 5-10 insects/ hill | 5-10 insects/ hill |
Rice Hispa | - | 2 adults or 2 damaged leaves/ hill | 1 adult or 1-2 damaged leaves/ hill or 10% damaged leaves | - | - |
Gundhi Bug | - | - | - | - | 1-2 bugs/ hill |
If the pest infestation reaches ETL, adopt the following management measures
Pests | Organic Management | Conventional Management |
YSB | Spray Neem oil/Neem products @ 2-3ml/L of water or Spinosad 45%SC @ 1ml/L of water or use Bacillus thuringiensis var. kurstaki or Metarhizium anisopliae or Beauveria bassiana biopesticides formulations | Spray Indoxacarb 14.5% SC @ 1ml/L or Emamectin benzoate 5% SG @ 1g/L or Flubendiamide 39.35% SC @ 0.3ml/L or Chlorantraniliprole 18.5% SC @ 0.3ml/L of water |
Leaf Folder | ||
BPH | Spray Neem oil/Neem products @ 2-3ml/L of water or use Metarhizium anisopliae or Beauveria bassiana biopesticides formulations | Spray Imidacloprid 200 SL @ 0.5 ml/L or Thiomethoxam 25 WP @ 0.3 g/L or Pymetrozine 50%WG @ 0.75g/L or Triflumezopyrim 10SC @ 0.4ml/L 0.5ml/L of water |
Rice Hispa | ||
Gundhi Bug |
Note: Repeat the application of biopesticides and neem-based products at 10-day intervals. Avoid repeated use of the same conventional insecticide to minimize the development of insecticide resistance in pest populations
Article contributed by Dr Moanaro, T.O, KVK Dimapur; Dr Bendangla Imsong, CTO KVK Dimapur, E Lireni Kikon, ACTO, KVK Dimapur, and Dr Phool Kumari, SS cum Head, KVK Dimapur
