Green leafhoppers (GLH), primarily Nephotettix malayanus and Nephotettix virescens, are critical pests in rice fields. They are notorious for spreading viral diseases, particularly tungro, which can severely impact rice yield.

What It Does

• GLH nymphs and adults feed by extracting plant sap using their needle-like mouthparts.
• They are vectors of viral diseases such as tungro, yellow dwarf, and transitory yellowing.

Why and Where It Occurs

• Preferred Environments:
  • Rainfed and irrigated wetland rice fields.
  • Less prevalent in upland rice.
• Contributing Factors:
  • Staggered planting promotes population growth.
  • High nitrogen fertilization makes rice plants more attractive.
• Environmental Suitability:
  • Active year-round in warm, humid regions.
  • In temperate areas, they overwinter and become active in spring.
  • High populations thrive at temperatures around 30°C and relative humidity of 80%.

How to Identify

• Symptoms of Infestation:

  • Stunted plants with reduced vigor.
  • Fewer productive tillers.
  • Withering or complete drying of plants.

• Physical Signs:

  • Pale yellow or white eggs inside leaf sheaths or midribs.
  • Yellow or pale green nymphs and adults, with or without black markings.
  • Feeding activity typically on dorsal leaf surfaces and lateral leaves.

• Differentiation:

  • Tungro symptoms can resemble nutrient deficiencies like nitrogen or iron deficiency.
  • Confirm presence by checking for virus-infected plants and the insect itself.

Why It Is Important

• GLH is a vector of major viral diseases, including tungro, which can cause significant yield losses.
• Direct feeding damage weakens the crop and reduces its productivity.

How to Manage

1. Resistant Varieties:

   • Use GLH- and tungro-resistant rice varieties.

2. Cultural Practices:

   • Synchronize crop establishment to limit overlapping generations.
   • Avoid staggered planting.
   • Transplant older seedlings (>3 weeks) to reduce vulnerability.
   • Rotate crops or intercrop with soybean to reduce alternate hosts.
   • Control weeds in fields and bunds.

3. Nutrient Management:

   • Apply nitrogen judiciously to prevent attracting GLH or weakening plant recovery.

4. Timing and Monitoring:

   • Avoid planting during peak GLH activity.
   • Use light traps to monitor population.

5. Biological Control:

   • Encourage natural enemies like parasitic wasps, mirid bugs, damselflies, and spiders.
   • Promote fungal pathogens targeting nymphs and adults.

6. Chemical Control:

   • In areas without tungro, avoid using insecticides unnecessarily.

Other Key Insights

• GLH adults have a lifespan of 20–30 days.
• Females lay 200–300 eggs in batches within the leaf midribs.
• GLH is most active between 7 PM and 12 AM and tends to concentrate near the water level.

Effective integrated pest management (IPM) strategies can help mitigate the impact of green leafhoppers and protect rice yields.