Effects of X-ray irradiation on development and reproduction of the oriental tobacco budworm, Helicoverpa assulta (Lepidoptera: Noctuidae)

Abstract

All stages of the life cycle of Helicoverpa assulta were irradiated with X-rays to determine the inhibitory dose for development and reproduction to serve as a quarantine treatment. The 100-Gy dose was effective for irradiation of eggs and larvae, and the 200-Gy dose was effective for pupae and mixed-sex adults. When either adult males or females were irradiated, however, 500 Gy was required to prevent the F1 eggs from hatching, and thus single-sex adults required much higher doses of X-ray irradiation. To gather confirmatory data applicable to phytosanitary quarantine regulations, pupae—the immature stage most resistant to X-ray irradiation—were placed inside paprika in boxes for exportation and were irradiated with 300 Gy as a small-scale confirmatory test. The dose given to 1,007 individual pupae resulted in 12.62 % survival, and 1.79 % of pupae emerged as normal adults; however, these adults produced only a few eggs that did not hatch, suggesting that a minimum dose of 300 Gy of X-ray irradiation will provide quarantine security for immature H. assulta in paprika exports.