THE MODIFICATION OF REPRODUCTION IN INSECTS TREATED WITH ALKYLATING AGENTS. I. INHIBITION OF OVARIAN GROWTH AND EGG PRODUCTION AND HATCHABILITY

¹ Entomology Research Division, Agric. Res. Serv., U.S.D.A., Kerrville, Texas

Female screw-worm flies (Cochliomyia hominivorax (Coquerel)) 0-4 hours old or 24±2 hours old were each treated topically by application to the dorsal thorax of 2 microliters of a solution of one of five aziridinyl chemosterilants. At 6 days of age, some mated females were given the opportunity to lay eggs and others were killed for measurements of the ovaries. The greatest inhibition of ovarian growth occurred during the endomitotic phase of the nurse cells (0-4 hours) and resulted in complete, or nearly complete, infecundity. The growth of ovaries of 24-hour-old females was but slightly or moderately affected, and the fecundity of such females was correspondingly greater than that of newly emerged females. However, the induction of many dominant lethal mutations in 24-hour-old flies greatly reduced or eliminated the fertility of such flies with resultant sexual sterility. It was concluded that the primary influence of aziridinyl compounds on the ovaries of 0- to 4-hour-old screw-worm flies is the inhibition of oogenesis and on those of 24-hour-old flies, the induction of mutations.

The authors gratefully acknowledge the excellent technical assistance of H. H. Meyners and F. C. Heep, Jr., Agricultural Research Technician and Laboratory Helper, respectively, Entomology Research Division, and the cooperation of the chemists of the Division in procuring the chemical substances studied.