Efficacy of diflubenzuron against tobacco leaf eating caterpillar

The nine different concentrations of diflubenzuron, a chitin synthesis inhibitor were tested in the laboratory against freshly laid eggs and those prior to hatching, larval and pupal stages of tobacco leaf eating caterpillar, Spodoptera litura Fabricius. The per cent unhatched eggs was ranged from 35.41 to 100.0 and 13.46 to 74.93 in various treatments applied at two stages of the eggs, respectively as against 12.22 and 8.88 per cent in control. The per cent larval mortality in various treatments was ranged from 46.66 to 100.0, 26.66 to 100.0, 21.66 to 100.0, 26.66 to 100.0, 23.33 to 91.66 and 20.00 to 86:66, respectively in progressive instars. Most of the affected larvae failed to shed off their exuviae at the time of moulting, turmed black and displayed morphological deformities. Diflubenzuron adversely affected larval growth and weight. The larval period was also prolonged in treated larvae as compared to that in control. The percentage of adults emerged from treated pupae was ranged from 0.0 to 100.0 as against 100.0 per cent in control.