Integrating chemical control with sterile insect releases in an integrated pest management programme for Thaumatotibia leucotreta

摘要

False codling moth Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae) is an important indigenous pest of citrus in southern Africa. Successful control is dependent upon integration of area-wide sterile insect releases and other suppression methods. The aim of this work was to test pyrethroid and organophosphate-based insecticides (tau-fluvalinate and chlorpyrifos) for their residual effect on mortality of released irradiated T.leucotreta male moths. Both of these insecticides were effective in killing irradiated T.leucotreta for 7days after application on leaves, after which degradation of the active ingredient resulted in a marked reduction in efficacy after 14days and rendering them harmless. Mortality was found to be similar for irradiated and non-irradiated male T.leucotreta after treatment. Consequently, even though these insecticides might have an effect on moths in the field, ratios of sterile:wild moths should not be altered. Supporting field data from six sites in the Sundays River Valley over a season of sterile insect releases showed the conventional chemical crop protection programme to be as effective as an integrated pest management programme in facilitating effective control of T.leucotreta through sterile insect releases. The study also confirmed that the ratios of sterile:wild male moths in the commercial citrus orchards were not affected by the application of insecticides. These findings confirm the high potential of sterile insect releases for control of T.leucotreta in citrus.