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

• Effects of gamma irradiation on Lobesia botrana mature larvae are examined.
• Results showed that a dose of 200 Gy was sufficient to prevent adult emergence from mature larvae.
• This dose (200 Gy) is less than the suggested generic phytosanitary irradiation dose of 250 Gy for Lepidopteran larvae.
• The dose is also much lower than the maximum allowed dose for irradiation of fresh fruits and vegetables.

Mature 5th instars of the grape vine moth, Lobesia botrana (Denis and Schiffermuller) were exposed to gamma radiation dosages ranging from 50 to 250 Gy. The effects of gamma radiation on pupation, adult emergence, sex ratio and rate of development were examined. Results showed that the radiosensitivity of the grape vine moth larvae increased with increasing radiation dose. The severity of the effect, however, depends on the criterion used for measuring effectiveness; adult emergence was more severely affected than pupation. Pupation was significantly affected at 150 Gy and decreased by about 25% at 250 Gy. Adult emergence, on the other hand, was significantly affected at 100 Gy and completely prevented at 200 Gy. Probit analysis of dose mortality data for pupation and adult emergence show that the LD99 for preventing subsequent development to pupae and adults was 2668 and 195 Gy, respectively. In addition, the rate of development of mature larvae to the adult stage was negatively affected and sex ratio was skewed in favor of males.