Evidence that sweet cherry (Prunus avium L.) is not a host of codling moth (Cydia pomonella (L.), Lepidoptera: Tortricidae) in British Columbia, Canada

Abstract

Before accepting a systems approach as an alternative to methyl bromide fumigation, the Ministry of Agriculture, Forestry and Fisheries (MAFF) of Japan requested a two year study to confirm that sweet cherry is not a host of codling moth, Cydia pomonella (L.) (Lepidoptera: Tortricidae) in British Columbia. Evidence was collected through trapping of adults using pheromones and fruit dissections for eggs and larvae in the three largest sweet cherry production regions in the interior of British Columbia: the North Okanagan, South Okanagan/Similkameen and Creston in 2015 and 2016. The Creston Valley is outside of the region served by Sterile Insect Release of codling moth, thus the survey included orchards with and without codling moth sterile insect technology. All cherry orchards were in proximity to apple orchards. No pest control measures that might affect codling moth were used in Year 1 of the study. Year 1 objective was to determine the average number of wild codling moth adults in an orchard where no pest control measures were applied (codling moth threshold). Codling moth pheromone traps were placed in cherry orchards. The highest weekly mean of wild trap captures was 12 codling moth adults per trap in Creston in Year 1. In Year 1, at least 10,000 harvested cherries per orchard were examined externally and by dissection per orchard. A total of 112,565 cherry fruit were individually examined. No codling moth eggs or larvae were found. In Year 2, pest control measures were applied to cherry orchards, and 600 harvested cherries per orchard were examined externally and by dissection per orchard. A total of 6311 cherry fruit were individually examined. No codling moth eggs or larvae were found under low (South Okanagan/Similkameen and North Okanagan regions) and moderate (Creston region) codling moth pest pressure. In 2016, lots from 10 orchards were presented for export certification to countries other than Japan, no insect pests were detected during the brown sugar flotation test. These results suggest that cherries are poor hosts of codling moth. This study supports a systems approach to quarantine security for export of BC fresh cherries to Japan.