Effect of silicic and salicylic acids on major insect pests and their natural enemies in rice

Abstract

Field, pot culture and laboratory experiments were carried out to study the effect of foliar spraying of silicic and salicylic acids against major pests of rice through inducing resistance, and their natural enemies like spiders and mirids. In the field experiment, leaf feeders and sucking insects were found significantly reduced with basal application of rice husk ash 500 kg/ha + silica solubilizing bacteria (SSB) @ 2 kg/ha with foliar spraying of silicic acid 0.5%. This was followed by basal application of calcium silicate 50 kg/ha with foliar application of silicic acid 0.5%. Similarly, significantly less stem borer incidence was observed with basal application of rice husk ash 500 kg/ha + SSB 2 kg/ha with foliar spraying of silicic acid 0.5%. Spiders and mirids were significantly less with basal application of calcium silicate 50 kg/ha along with foliar application of silicic acid 0.5%. In short, significantly reduced damage by the leaf folder, stem borer and gall midge besides reduction in the population of brown plant hopper (BPH), spiny beetle, ear head bug and increased natural enemies were observed with basal application of rice husk ash 500 kg/ha + SSB 2kg/ha and foliar spraying of silicic acid 0.5%. Basal application of calcium silicate 50 kg/ha with foliar application of silicic acid 0.5% was the next best. Correlations with inferences on the biology of BPH, leaf folder and biophysical factors (silicified cells and leaf erectness and biochemical factors viz., peroxidase content and silica content) corroborated their efficacy.