Effects of gamma irradiation on the grape vine moth, Lobesia botrana, eggs

Abstract

Eggs of the grape vine moth, Lobesia botrana (Denis and Schiffermuller), ranging in age from 1–24 to 73–96h, were exposed, at 24h intervals, to gamma radiation ranging from 25–600Gy. The effects of gamma radiation on egg hatch, pupation, adult emergence, sex ratio and rate of development were examined. Results showed that the radiosensitivity of the grape vine moth eggs decreased with increasing age and increased with increasing radiation dose. Egg hatch in 1–24h old eggs was significantly affected at 25Gy and completely prevented at 100Gy. At the age of 25–48h, radiation sensitivity was only a little lower; egg hatch at 100Gy was <1% and at 125Gy no egg hatch was observed. Egg sensitivity to gamma irradiation decreased significantly in the 49–72h age group; egg hatch was 66% at 100Gy, and 500Gy did not completely stop egg hatch (<1%). Eggs irradiated a few hours before egg hatch (73–96h old) were the most resistant; 150Gy had no significant effect on egg hatch and at 600Gy over 33% of the eggs hatched. When pupation or adult emergence was used as a criterion for measuring effectiveness, however, the effects of gamma radiation were very severe. In the most resistant age group (73–96h old), 150Gy completely prevented pupation and adult emergence and all larvae resulting from eggs irradiated <49h old died before pupation. In addition, the rate of development of immature stages resulting from irradiated eggs was negatively affected and sex ratio was skewed in favor of males.