Some aspects of the action of diflubenzuron and trifluron on food consumption, growth rate and food utilization by Spodoptera littoralis larvae

Fourth-instar larvae of the cotton leafworm, Spodoptera littoralis (Boisd.) were fed on castor-bean leaves treated with the chitin-biosynthesis disrupting agents diflubenzuron and its analogue trifluron. There was a reduction in the consumption of food. Considerable decrease in growth rate was also recorded. The efficiency of converting ingested and digested food into body substances also showed an obvious reduction especially in larvae fed on diflubenzuron-treated leaves. On the other hand, the approximate digestibility coefficient increased considerably in larvae fed on leaves treated with diflubenzuron and trifluron.