Irradiation as a quarantine treatment for fruit subject to infestation by codling moth larvae

The codling moth, Cydia pomonella (L.), is a pest of deciduous fruit throughout most of the world, except for Japan, Taiwan, Korea, and other limited areas. Its larvae infest apples, pear, walnuts, and many other deciduous fruit crops. Japan and Korea permit importation of cherries, a reported host, that have been fumigated using methyl bromide but prohibit importation of other host fruits from countries in which the codling moth is known to occur. The codling moth overwinters as diapausing larvae in cocoons. Research conducted at Yakima, Washington, has shown that nondiapausing codling moth larvae can be killed by methyl bromide fumigation at 32 g/m/sup 3/ for 2 hours at 200C. This research has also shown that diapausing larvae are more resistant to methyl bromide than are nondiapausing larvae. Recently the Food and Drug Administration proposed approval of irradiation at a dose not exceeding 1 kGy as a treatment for commodities of quarantine importance that may be infested with insects. Exposure of immature insects to less than 1 kGy should prevent emergence of viable adults and would, therefore, be adequate to meet most quarantine restrictions. Research at Yakima to determine if irradiation can be considered as a potential quarantine treatment for codling moth larvae has shown that exposure of larvae at doses up to 100 Gy from a cobalt-60 gamma source will significantly reduce emergence of normal adults. Projecting these date, the authors estimated the dose required for quarantine security (99.9968 percent mortality), based on emergence of apparently normal adults from treated larvae, to be 145 Gy