Evaluation of a methyl bromide quarantine treatment to control codling moth (Lepidoptera: Tortricidae) on nectarine cultivars proposed for export to Japan

Our experiments showed that testing required by regulatory agencies to demonstrate the efficacy of a quarantine treatment using 48 g/m3 methyl bromide for 2 h at 21 degrees C or above and 50% load was unnecessary to control codling moth, Cydia pomonella (L.), on every nectarine cultivar proposed for export to Japan. Ovipositional tests for codling moth on nine nectarine cultivars showed no differences in acceptability among cultivars that might cause higher populations in harvested fruit and affect quarantine security levels. Measurements of egg chorion and fruit cuticle showed that codling moth eggs were not affected by different nectarine cultivars and other fruit substrates. No differences that would reduce the efficacy of the methyl bromide quarantine treatment were found in codling moth mortality to methyl bromide fumigation in dose-response tests on different substrates, including nectarine, peach, plum, and apple cultivars and waxed paper. A confirmatory test resulted in 100% mortality of 27,174 1-d-old codling moth eggs. The true survival proportion based on all confirmatory tests was less than or equal to 20 per 1 million at the 95% CL. A concentration X time product of (average +/- SD) 68.0 +/- 3.0 g.h/m3 methyl bromide was considered a useful measurement to help maintain treatment security for control of codling moth on all nectarine cultivars