Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/19/1999
Publication Date: 6/20/2000
Citation: Yokoyama, V.Y., Miller, G.T., Hartsell, P.L., Leesch, J.G. Large-scale, on-site confirmatory, and varietal testing of a methyl bromide quarantine treatment to control codling moth (lepidoptera: tortricidae) in nectarines exported to japan. Journal of Economic Entomology. Volume(93):1025-1030. Interpretive Summary: An economical method was needed to implement a methyl bromide quarantine treatment to control codling moth in nectarines exported to Japan. Fumigation in shipping cartons was the method of choice for fruit packers and exporters. The Japanese government required large-scale testing and a demonstration test in the presence of a Japanese official to confirm that the treatment would control the pest when fruit was packed in cartons. Th tests were successfully conducted according to scientific protocols and the procedure was approved for the export of 10 previously tested varieties of nectarines in 1995. New varieties of nectarines are now in production in the San Joaquin Valley of California. The new varieties could not be shipped under the quarantine treatment program without basic tests to show the response of codling moth to different doses of methyl bromide on each variety. Such testing has been termed varietal testing and may be unnecessary. Old nectarine varieties previously approved for export to Japan were subjected to retests to help determine the usefulness of the procedure. The retest data showed that varietal testing is subject to natural variations. The data was used to support the argument that varietal testing is an inappropriate practice.
Technical Abstract: A total of 30,491 codling moth, Cydia pomonella (L.), 1 d-old eggs on May Grand nectarines in large-scale tests (2), and 17,410 eggs on Royal Giant nectarines in on-site confirmatory tests (4) were controlled with 100% mortality after fumigation with a methyl bromide quarantine treatment (48 gm3 for 2 h at greater than or equal to 21C and 50% volume chamber load) o fruit in shipping containers for export to Japan. Ranges (mean +/- SEM) were for percentage sorption 34.7 +/- 6.2 to 46.5 +/- 2.5, and for concentration multiplied by time products 54.3 +/- 0.9 to 74.5 +/- 0.6 g.h/m3 in all tests. In large-scale tests with May Grand nectarines, inorganic bromide residues 48 h after fumigation ranged from 6.8 +/- 0.7 to 6.9 +/- 0.5 ppm (mean +/- SEM) which were below the U.S. Environmental Protection Agency tolerance of 20 ppm, and organic bromide residues were <0.01 ppm after 1 d and <0.001 ppm after 3 d in storage at 0-1C. After completion of large-scale and on-site confirmatory test requirements, fumigation of 10 nectarines cultivars in shipping containers for export to Japan was approved in 1995. Comparison of LD50s developed for methyl bromide on 1 d-old codling moth eggs on May Grand and Summer Grand nectarines in 1997 versus those developed for 9 cultivars in the previous 11 yr showed no significant differences in codling moth response among cultivars.