Developmental effects of ionizing radiation in Aedes aegypti

All stages of Aedes aegypti were exposed to radiation in doses ranging from 500 to 32,000 r. A 10,000 cu Co-60 source, delivering approximately 125 r/min. was used to determine the radiosensitivity relating to egg hatch, growth and development, viability to adulthood, longevity, cell division, as well as fecundity and fertility in both sexes. Fully embryonated eggs exposed to 500 r resulted in retarded development of larvae hatching from them but proved to be more radioresistant than eggs undergoing embryonation. Prolonged developmental time was related to a decrease in mitotic rate. The greater sensitivity of the 1st 3 larval stages over embryonated eggs appeared to be due to mitotic activity in the larval stages and its absence in quiescent eggs. Damage on the whole was directly proportional to dose and indirectly proportional to the stage of development reached; e.g., adult longevity was decreased when young larvae were exposed to 500 r, and when pupae and adults received 8000 r or more. The reproductive systems of both sexes were highly sensitive but fecundity and fertility were not affected to the same extent in the two. While treatment in all stages retarded or completely inhibited gonadal development and function, a low dose of 500 r to females in the 1st instar initiated a statistically significant increase in egg fecundity. Female sterility was achieved with a lack of fecundity at exposures of 4000 r to pupae and adults. Male sterility was related to production of infertile sperm at exposures of 8000 r. Cytological studies of gonads in control and treated organisms provided evidence for the observed radiationinduced decrease in reproductive potential.