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

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.