Pest:Rice gall midge

Orseolia oryzae Cecidomyiidae

The adult is a small midge, delicate mosquito like insect with long legs and red abdomen.The total life cycle occupies 2-3 weeks(egg period 3-5 days; larval period 1-2 weeks; pupal period 3-8 days).Eggs are laid at the base of leaves.The emerging larva crawls down between leaf sheaths till it reaches the growing points.

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  • Pest 1
  • Pest 2
  • Pest 3
  • Pest 4
  • Pest 5
  • Pest 6

Symptoms

  • As a result of feeding by the larva (maggot) an oval chamber is formed around the maggot.
  • Gradually this chamber grows out as an elongated cylindrical gall called the “Silver Shoot” because of its light shiny appearance.
  • The gall is small and is not seen out side during the larval stage of the insect. Elongation of the gall takes place during pre pupal and pupal stage.
  • Nursery to late tillering phase of the crop is subjected to infestation. The midge infestation in the early stage of the crop induces subsidiary tillering and they are also infested.
  • Monsoon crop suffers more due to infestation by the gall midge, may be due to high rain fall and low maximum temperature. In general maximum infestation by the pest occurs on crop planted during June.
  • Weeds such as Ischaemum aristatum Cynodon dactylon, Echinochloa spp. and Isachene spp are heavily infested by the insect when susceptible stages of rice are not available in the field.

Procedure for Observation

Randomly mark 4 one square meter plots in 0.4 Ha. Assess the damaged tillers (silver shoots ) and total number of tillers and calculate the % damage.

ETL

  • Nursery stage : one silver shoot /m.sq.
  • Planting to pre tillering : One gall /m.sq. in endemic areas or 5% affected tillers in non endemic areas.
  • Mid tillering: 10 % silver shoots.

    • Control Measures

  • Being an internal feeder and since the damage it causes become visible only after the gall is produced only preventive measure will be of any use against the pest.
  • Use tolerant/resistant varieties- Pavithra,Panchami,Uma.
  • Avoid late transplantation during first crop season.Careful monitoring of the crop of the first crop season.
  • While in Kuttanad areas monitor the crop in the month of July during additional crop season and October during Puncha season.Destroy the weeds which serve as collateral hosts.
  • Dipping germinated seeds in 0.2 % Chlorpyriphos for three hours before sowing give protection up to 30 days.
  • In transplanted crops roots of seedlings may be dipped in 0.02 % chlorpyriphos solution for 12 hrs before planting.
  • In areas where the pest is of regular occurrence apply granules of Quinalphos 5G @ 25 Kg/Ha. The granules should be broadcast in 2-3 cm of water and the field should be impounded for at least 4 days.
  • Spray application of Qunalphos 25 EC at 1000 ml/Ha.Gall midge at its pupal stage is parasitized by Platygaster oryzae.