Thaumatotibia leucotreta and the Navel orange: ovipositional preferences and host susceptibility

Abstract

AbstractFalse codling moth, Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae), presents a significant threat to the South African citrus industry. To limit income loss due to direct larval damage or from fruit rejection due to the phytosanitary status of this pest, additional pre‐harvest control techniques are required for Navel oranges, which are known to be susceptible to T. leucotreta damage. A number of Navel orange cultivars have been developed, and differences in female T. leucotreta ovipositional preference and susceptibility of cultivars to larval penetration are known to exist. Navel orange cultivars were grouped according to time of maturity (early, mid‐ and late season). Female T. leucotreta were subjected to choice and no‐choice tests with these cultivars, measured by oviposition. Host susceptibility was tested by allowing neonate T. leucotreta larvae to penetrate the different Navel cultivars. In the early maturing group, Fischer Navels were least preferred for oviposition and the least susceptible to larval penetration. The mid‐ and late season maturing groupings showed limited differences in oviposition preference, although host susceptibility did appear to be an important factor in assessing the vulnerability of fruit to T. leucotreta. Despite being widely planted in South Africa, the mid‐season Palmer Navels were highly susceptible to larval penetration, while for the late season cultivars, Cambria and Glen Ora Late were the least susceptible to T. leucotreta. As a result of these laboratory trials, it is recommended that farmers increase cultivation of Fischer Navels as the principal early season cultivar, avoid Palmer Navels in favour of other mid‐season maturing cultivars and give preference to the late maturing Cambria and Glen Ora Late cultivars, to limit T. leucotreta damage.