Experiments with a Systemic Insecticide for the Control of Schoenobius incertulas (Wlk.) (Lepidoptera, Pyralidae), A Stem Borer of Paddy in West Bengal

Summary

Experiments were carried out in West Bengal to ascertain whether the Paddy Stem Borer, Schoenobius incertulas (Wlk.) could be controlled by “Tetrax” 1, a systemic insecticide containing technical schradan equivalent to approximately 42 per cent, octamethyl pyrophosphoramide + approximately 25 per cent, triphosphoric acid pentadimethylamide.

In a preliminary experiment, treatment had little effect on the damage caused by the borer but the yield of grain was higher from a treated plot than from a control plot.

A further experiment was carried out, the following year, in which the seed was soaked in a 0·1 per cent, water solution of “Tetrax” 1 for eight hours before sowing in the seed beds. The seedlings were lifted about 2½ months later and steeped in 0·1 per cent. “Tetrax” 1 for eight hours before transplanting into two plots, each 32 ft. × 32 ft. About three weeks later the plants were sprayed with a solution of the same strength. Two plots of similar size, in which the paddy had received no treatment, were maintained as controls.

Again there was very little difference, between the treated and untreated plots, in the damage caused to the ear heads by the pest, but the treated plots produced 108·68 lb. of grain as against 77·27 lb. for the untreated plots. The increase was largely due to an increase in the number of ear heads per plant.

The incidence of the borer was too low in both experiments to determine whether “Tetrax” 1 exercised any appreciable control, but the treatment did give rise to a higher yield of grain under the conditions of the experiments.