Title: Effect of Gamma Radiation on the Development and Reproduction of the Brown Planthopper, Nilaparvata lugens (STÅL) (Homoptera : Delphacidae)
Abstract: N. lugens was irradiated at 2.5 to 30 krad in the 5th-instar stage by using 60Co. The minimum effective doses of gamma radiation to 5th-instar female and male nymphs causing a 100% reduction in egg viability were estimated to be about 2.5 (or somewhat lower) and 6.2 krad, respectively. At 6.2 krad the values of % adult emergence (males and females together), % adult malformation (do.), mean longevity of males (days after irradiation), and LD 50 (do., males and females together) were estimated to be about 100, 19, 17 (29 for the control), and 14 (26 for the control), respectively. Lethal mutation sterility was expected at this dose-level. The internal reproductive organs of adults were anatomically and histologically examined. The spermatozoa were motile in male adults irradiated at 30 krad. The minimum effective dose of gamma radiation to 5th-instar female nymphs required for the interruption of egg-formation was estimated to be between 15 and 20 krad, higher than the minimum effective dose for cessation of egg-laying (10.4 krad).