Pest:Rice blue beetle(leptispa)

Leptispa pygmaea Chrysomelidae

The rice blue beetle reported earlier as a minor pest is recently attaining the status of a major pest by causing much concern in several rice growing tracts of Palakkad, Kannur and Kasaragod Districts. The beetle lays oval shaped eggs on the rice leaves. The eggs hatch in to creamy white grubs with two projections on the head and two tubular projections on the posterior end of the body. The grub has 5 larval instars. The grub pupates on the leaves. The adult is a small elongated metallic greenish-yellow coloured beetle.

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  • Pest 1

Symptoms

  • The adult and grubs are feeders of surface tissues of leaves.
  • The feeding lines are narrow.The attacked leaves turn membraneous and dry up.
  • The adults feed especially on tender leaves which result in partial upward rolling of lamina.
  • Adult prefer to feed on the dorsal surface of the leaves by scraping linear streaks.They also feed on the ventral leaf surfaces rarely.

Procedure for Observation

Randomly mark 4 one meter sq. per 0.4 Ha. Observe five hills at random in a sq.m and count the total number of bugs without disturbing the plant and work out average per hill.

ETL

  • Flowering and after; 1-2 bugs per hill.

    • Control Measures

  • Keep the field and bunds free of weeds and grasses.
  • Avoid overlapping of cultivation in a padasekaram.
  • Collect and destroy bugs using hand nets- before flowering.
  • Install flame torches after dusk to attract and kill the bugs.
  • Spray Bauveria bassiana at 20 g per lit of water.
  • When bug is seen in large numbers apply one of the following insecticides either before 9 am or after 3 pm so that fertilization of the flowers is not affected. Malathion 50 EC @ 1000ml/Ha Carbaryl 50 WP @ 2 kg/Ha Quinalphos 25EC 1000 ml/Ha