EFFECTS OF CERTAIN INSECTICIDES ON EGGS OF SPODOPTERA LITTORALIS

Abstract

Seven chemical insecticides were tested for their ovicidal activity against Spodoptera littoralis eggs, using two methods, namely dipping of tafla leaves containing 0-1 day old eggs and o-day old eggs were deposited on insecticide residues on tafla leaves. Rynaxypyr was the most promising. It was taken as the standard insecticide and given an arbitrary index value of 100 units, when 0-1 day old eggs were treated directly by dipping in insecticide solution. As for the indirect ovicidal activity, emamectin benzoate came first and was given arbitrary index value of 100 units. On the other hand spinetoram, in comparison showed the least indirect ovicidal effect. Regarding the inhibitory action, it was obvious that rynaxypyr and indoxacarb exhibited high inhibitory activity (100%) in suppressing the number of deposited eggs when moths were subjected to 100 ppm and it was followed closely by pyridalyl, emamectin benzoate and spinetoram being 97.8, 97.0 and 95.3%, respectively. However, all insecticides showed variable degrees of inhibition at the least concentration tested (0.1 ppm), except spinosad and spinetoram having no inhibition activity for deposited eggs.