Thaumatotibia leucotreta (Meyrick)
[(]Also known as Cryptophlebia leucotreta (Meyrick)].
Common name: False codling moth.
Taxonomic position: Insecta, Holometabola, Lepidoptera, Tortricidae.
Geographical distribution: Africa, the Middle East, occasionally found in Europe and North America, CABI Distribution Maps of Plant Pests #352, 2002.
Morphology: Young larvae are 1 mm in length, whitish and spotted; mature larvae are about 15 mm long, orange to pink in color, with brown heads. Adults 7-8 mm long, body mostly brown, forewings color variegated, brown to grey with a white spot in the middle, hindwings light brown to grey.
Host plants: This moth is polyphagous, feeding on more than 70 plant species placed 40 families.
Life history: A female can lay several hundred eggs (up to 450) on any available host fruits. The young larvae immediately burrow into the fruit and feed for several weeks, then drop to the ground to pupate. The pest, which has no diapause or a quiescent period, may raise five or more annual overlapping generations and can live for several weeks. The moths are poor fliers and active only at night.
Economic importance: In Africa, T. leucotreta is a major pest of avocado, citrus, and cotton, being also very harmful to macadamia nuts and pomegranates, and it has been placed on the EPPO A2 List. Infestations of citrus lead to premature fruit drop, and the damage, although variable, can reach up to 90%. Cotton bolls are penetrated by the larvae, which first consume the walls and then feed on the seeds, which may then be invaded by molds. The stems of stone fruits are initially attacked by the larvae, which then feed on and around the stone. Attacks of this pest show alternate-year infestation severity.
Management
Monitoring: Light and sex pheromonal traps are used to attract adults, traps being placed about 150-200 m from each other and inspected weekly. Potential hosts are to be visually inspected for pest presence during the growing season, looking for poor growth, rot, holes in the fruits of macadamia nuts or at cotton bolls, adults hidden in foliage and for crawling larvae. The first four rows bordering citrus or stone fruit orchards should be examined carefully.
Horticultural methods: Removal of all fallen fruits and other fruit trees growing near the orchard. Bags used to cover avocado fruit reduces infestation levels.
Irradiation: Male and female mature pupae and newly emerged adults were treated with increasing doses of gamma radiation. Decreased fecundity and increased mortality during development were observed, along with a significant male-biased shift in the sex ratio of the progeny.
Sterile male technique (SIT): Sterile insect releases in South African citrus orchards greatly reduced the pest status of T. leucotreta, resulting in pre-harvest crop losses decreasing by 93 % after three years. ,
Chemical control: Several pesticides, such as a pyrethroid and a chitin synthetase inhibitor were used.
Biological control: The moth is attacked by the egg parasitoid Trichogrammatoidea cryptophlebiae Nagaraja (Trichogrammatidae) but it does not always provide sufficient control. A granulosis virus preparation (trade name Cryptex) that kills the pest is also available and may be applied with the parasitoid. Isolates of the entomopathogenic fungi Beauveria and Metarhizium are being selected for use against the borer.
Integrated borer management: The area-wide borer control approach advocated in South Africa combines parasitoid releases, applications of the granulovirus and the a chitin synthesis inhibitor, and the sterile insect technique, in various combinations.
References
Bloem, S., Carpenter, J.E. and Hofmeyr, J.H. 2003 Radiation biology and inherited sterility in false codling moth (Lepidoptera: Tortricidae). Journal of Economic Entomology 96:1724-1731.
Carpenter, J., Bloem, S. and Hofmeyer, H. 2007. Area-wide control tactics for the false codling moth Thaumatotibia leucotreta in South Africa: a potential invasive species. In: Vreysen, M.J.B,. Robinson, A.S. and Hendrichs, J. (eds.), Area-Wide Control of Insect Pests: From Research to Field Implementation. Springer, Dordrecht, pp. 351–359.
Coombes, C.A., Hill, M.P., Moore, S.D. and Dames J.F. 2016. Entomopathogenic fungi as control agents of Thaumatotibia leucotreta in citrus orchards: field efficacy and persistence. BioControl IN PRESS.
Fullard, F. 2015. Beauveria and Metarhizium against false codling moth (Lepidoptera: Tortricidae): A step towards selecting isolates for potential development of a mycoinsecticide. African Entomology 23: 239-242.
Gilligan, T. M., M. E. Epstein, and K. M. Hoffman. 2011. Discovery of false codling moth, Thaumatotibia leucotreta (Meyrick), in California (Lepidoptera: Tortricidae). Proceedings of the Entomological Society of Washington 113: 426-435.
Grové. T., de Beer, M.S. and Joubert, P.H. 2010. Developing a systems approach for Thaumatotibia leucotreta (Lepidoptera: Tortricidae) on ‘Hass’ avocado in South Africa. Journal of Economic Entomology 103: 1112-1128.
Hofmeyr, J.H., Carpenter, J.E., Bloem, S., Slabbert, J.P., Hofmeyr, M. and Groenewald, S.S. 2015. Development of the sterile insect technique to suppress false codling moth Thaumatotibia leucotreta (Lepidoptera: Tortricidae) in citrus fruit: research to implementation (Part 1). African Entomology 23: 180-186.
Sullivan, M. 2007. CPHST Pest Datasheet for Thaumatotibia leucotreta. SDA-APHISPPQ-CPHST, Revised January 2014.
Wysoki, M. 1986. New records of lepidopterous pests of Macadamia in Israel. Phytoparasitica 14: 147-148.
http://www.eppo.int/QUARANTINE/Alert_List/insects/thaumatotibia_leucotreta.htm