Radiation Biology of Eldana saccharina (Lepidoptera: Pyralidae)

Laboratory-reared male and female Eldana saccharina Walker (Lepidoptera: Pyralidae: Gallerinae)—a major pest of sugarcane (Saccharum spp.; Poales: Poaceae) in South Africa—were exposed to increasing doses of γ-radiation to assess this species' suitability for the sterile insect technique as part of an area-wide integrated pest management (AW-IPM) program. Irradiated male and female moths were crossed with non-irradiated counterparts and irradiated counterparts at the same radiation dose. Male and female moths were treated with radiation doses of 150, 200, 250, 300 and 350 Gy, and the following crosses were made: irradiated males (T♂) mated with untreated females (U♀) and irradiated females (T♀) mated with untreated males (U♂). Males and females of the T♀ × T♂ cross were exposed to the same radiation doses except in the 350 Gy treatment. Fertility (egg hatch) declined significantly with increasing doses of radiation in all crosses. Female progeny from the T♀ × U♂ and T♀ × T♂ crosses were more sensitive to irradiation than female progeny from the U♀ × U♂ and U♀ × T♂ crosses and were completely sterile when treated with either 200 Gy or 150 Gy. Treated males mated with untreated females still had a residual fertility of 0.19% when exposed to 350 Gy of radiation. The fertility of E. saccharina is therefore sensitive to increasing doses of ionizing radiation and this species is a suitable candidate for further development of the SIT as a component of an AW-IPM program. The fecundity of untreated E. saccharina females mated with irradiated males was not affected by radiation. The availability of a great number of infertile eggs can be regarded as a benefit in a program where natural enemies are combined with the SIT because non-fertile eggs can provide additional hosts for egg parasitoids and be a food source for predators.