X-ray based irradiation of navel orangeworm for sterile insect control

Authors: Haff, Ronald - Ron; Ovchinnikova, Inna; Light, Douglas

Submitted to: United States-Japan Cooperative Program in Natural Resources
Publication Type: Proceedings
Publication Acceptance Date: 10/15/2017
Publication Date: 11/15/2017
Citation: Haff, R., Ovchinnikova, I., and Light, D. X-ray based irradiation of Navel Orangeworm for Sterile Insect Control. The United States-Japan Cooperative Program in Natural Resources (UJNR) Food and Agriculture Panel 46th Annual Meeting. Hiroshima, Japan. November 11-15, 2017.

Interpretive Summary: The navel orangeworm (NOW) is a pest of California tree nuts, including almonds, pistachios, and walnuts. NOW damage is also correlated with infection by certain fungi which produce toxins which are strictly regulated with tolerances at ppb levels. Chemical insecticides have been the traditional control method, but such products are under increasing regulatory restriction by the EPA due to food and environmental safety concerns. Alternative insecticides along with pheromone mating disruption are now the standard. Sterile insect technique (SIT) could provide the means for further suppression if incorporated into area wide programs. SIT involves the mass-rearing, sterilization, and release of insects that then mate with a targeted wild population causing infertile offspring. SIT has been highly successful in suppressing wild populations of many pests, including the codling moth and the pink bollworm. Use of X-rays as a substitute for gamma sources is desirable due to the inherent difficulties and cost of safely protecting gamma facilities and obtaining radioisotope sources. X-ray technology offers a highly secure and less vulnerable method of irradiation than gamma sources, thus increasing the potential for the safe expansion of SIT programs worldwide. The objective of this study was to demonstrate NOW sterilization by x-ray irradiation. Irradiated males were crossed with non-irradiated females and their resultant egg count, fertility, and hatching were compared to normal moths.

Technical Abstract: The navel orangeworm (NOW) is a pest of California tree nuts, including almonds, pistachios, and walnuts. NOW damage is also correlated with infection by Aspergillus flavus and subsequent mycotoxin contamination, primarily aflatoxins. These potential carcinogens / animal toxins are strictly regulated with tolerances at ppb levels. Organophosphate insecticides have been the traditional control method, but such products are under increasing regulatory restriction by the EPA due to food and environmental safety concerns. Alternative insecticides along with pheromone mating disruption are now the standard. Sterile insect technique (SIT) could provide the means for further suppression if incorporated into area wide programs. SIT involves the mass-rearing, sterilization, and release of insects that then mate with a targeted wild population causing infertile offspring. SIT has been highly successful in suppressing wild populations of many Lepidopteran pests, including the codling moth and the pink bollworm. Use of X-rays as a substitute for gamma sources is desirable due to the inherent difficulties and cost of safely protecting gamma facilities and obtaining radioisotope sources. X-ray technology offers a highly secure and less vulnerable method of irradiation than gamma sources, thus increasing the potential for the safe expansion of SIT programs worldwide. The objective of this study was to demonstrate NOW sterilization by x-ray irradiation. Irradiated males were crossed with non-irradiated females and their resultant egg fecundity, fertility, and hatching of F1 progeny were compared to normal moths. Also, inherited sterility was assessed through emergence of F1 adults and their crossing with fertile counterparts followed again by assessment of resultant egg fecundity, fertility, and hatching of F2 progeny.