The toxic effect of diflubenzuron on Spodoptera littoralis eggs and on their respiration

The mortality rates of Spodoptera littoralis eggs of different ages when dipped in aqueous dilutions of a liquid diflubenzuron formulation were investigated. Eggs 2-3 days old were less sensitive than younger eggs, 0-1 day old. The respiratory rate of eggs 0-1 day old, 1 or 2 days after treatment, was the same as in the control. Eggs in the control hatched on the next day; on this day, respiration in the treated eggs decreased rapidly, but further decrease was then gradual and the base line was not reached until 11 days after treatment, or 9 days after the maximum respiratory rate had been obtained. The curve with diflubenzuron resembled that obtained with parathion.