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

Abstract

False 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.

The Cryptophlebia Leucotreta Granulovirus—10 Years of Commercial Field Use

“…Both of these theories are well supported [ 2 ]. However, this would certainly not be the case for more susceptible citrus types, such as Navel oranges, which are known to be subject to heavier attack from earlier in the growing season [ 44 ].…”

Evaluation of The Magnitude of Citus Yield Losses Due to African Citrus Triozid, False Codling Moth, the Greening Disease and Other Pests of Economic Importance in Kenya

“…Reed (1974) described losses of between 42 and 90% in late crops of cotton in Uganda while Blomefield (1989) reported losses of up to 28% in a late peach crop in South Africa. Other significant losses attributed to FCM is poor marketability of fruits as Love et al (2014) explains that FCM leads to economic loss in South Africa through fruit rejection due to the phytosanitary status of this pest. To manage this pest, good sanitation, destroying wild and cultivated hosts as well as scouting regularly for early detection is recommended.…”

Agathis bishopi (Hymenoptera: Braconidae) as a Potential Tool for Detecting Oranges Infested with Thaumatotibia leucotreta (Lepidoptera: Tortricidae)

“…Before infestation with T. leucotreta larvae, fruit were removed from the cold room and kept at room temperature for 24 h. In order to obtain uniformly infested fruit, 10 newly emerged 1st instar T. leucotreta larvae were carefully removed from a jar (containing hatched larvae) using a paintbrush and placed individually onto the fruit rind. Infested and healthy fruit were kept in the same room (25°C ± 2, 30 % RH ±10 and 12 L: 12D photoperiod) (Love et al 2014) for 3-4 days before their use in bioassays. Based on preliminary observations under these conditions, 1st instar T. leucotreta larvae placed on fruit reached 2nd instar between 3 and 4 days after inoculation.…”

“…Considerable research has been recently undertaken to develop more robust management options for T. leucotreta such as screening for resistant cultivars (Love et al 2014), and improved preharvest (Li and Bouwer 2012;Coombes et al 2013;Opoku-Debrah et al 2013) and postharvest (Johnson and Neven 2010;Boardman et al 2012) control measures. Although considerable success has been recorded in the preharvest and postharvest control of T. leucotreta, limited research has focused on developing improved technology for postharvest detection of infested fruit, particularly in the packhouse where fruit is sorted and packed for export.…”