THE SILICON ACCUMULATION IN COTTON PLANT AT DIFFERENT CONCENTRATIONS AND DOSES OF SODIUM SILICATE AND EFFECT ON HONEYDEW SECRETION, LONGEVITY AND MORTALITY OF 1^ST INSTAR OF MEALYBUG (PHENACOCCUS SOLINOPSIS)

Effect of different concentrations and doses of sodium silicate on the silicon accumulation and honeydew secretion, longevity and mortality of 1^st instar Phenacoccus solinopsis in cotton was evaluated under the laboratory conditions. Honeydew secretion was reduced to 2-14 times over control when 1^st instar nymphs were fed on plants treated with different concentrations and doses combinations of sodium silicate. Approximately 10-61 times higher mortality and 1.3-3 times longer life of 1^st instar nymph and 1.4-4 times higher silicon accumulation in plants was observed under different concentrations and doses combinations of sodium silicate. Silicon concentration in plants had highly significant and positive correlation with longevity but highly significant and negative correlation with the honeydew secretion of 1^st instar nymphs of cotton mealybug. The silicon concentration in plant explained 71.6 % variation in the number of honeydew drops/life-span, 54.7 % variation in the percentage mortality and 51.5 % variation in the longevity of 1st instar nymphs. Sodium silicate 10-25 % concentrations at the dose rate of 6-15 ml/pot or per 500g soil can be used as a source of silicon and reevaluation under field trails, before floating sound recommendation for the farmer use in cotton against cotton mealybug.