Abstract
Apholate administered orally to the fifth instar larvae at concentrations of 300 and 500μg per larva significantly reduced the number of eggs deposited in adults and hatchability of eggs. The effect of the chemical was more striking when applied at the beginning or the middle of the fifth instar than at the end of the same instar. In histological observation, it was noted that cell destruction occurred 48 hours after the treatment in the region in which nurse cells and oocytes were differentiating, however, cell destruction ceased about 120 hours after the treatment and cellular development recovered to normal. On the other hand, about 72 hours after the treatment, the chromatin of the nurse cells which had already finished differentiation at the time of treatment were clumped in masses and the nuclei were vacuolated. No visible changes were observed in oocytes. After this period the development of the nurse cells continued normally as well as those in the control. Normal growth was maintained up to the prepupal stage. At this stage a sudden degeneration occurred not only in the nurse cells but also in the oocytes themselves and were almost completely degenerated at pupation. It was suggested that as the oocyte development progressed, higher concentrations of the sterilant were needed to produce adverse effect. Cellular degeneration did not occur at the stage in which nurse cells were reduced in size and the oocytes were surrounded by the follicle cells vertically arranged in a line.
