Implementation of biological control options against false codling moth in laboratory and field trials

PROJECT TITLE:    Implementation of biological control options against false codling moth in laboratory and field trials

Project leader:       Pia Addison (Stellenbosch University)

Contact:                    pia@sun.ac.za

Duration:                   1 January 2019 – 31 March 2023

Problem identification and project objectives:

False codling moth (FCM) remains a priority quarantine pest for deciduous fruit and grapevine. Several biological control agents (insects, nematodes, fungi) have been tested successfully in laboratory scale experiments. These biological control agents include the use of entomopathogenic nematodes (EPNs), entomopathogenic fungi (EPF) and parasitic wasps. These organisms will be applied in more natural laboratory conditions individual and in combination, as well as in small-scale field experiments to assess effectivity. This will allow for the future commercial implementation of these biologicals. The main aim of this project is to determine the efficacy and the application of biological control agents under small-scale field experiments against the false codling moth.
False codling moth is a major pest of quarantine importance on deciduous fruit and citrus (Venette et al. 2003; CAB 2007, Bloemfield 1989). In the Western Cape, False codling moth is known to have developed resistance to the majority of insecticides (Hofmeyr & Pringle 1998). In South Africa, other control tactics such as use of natural enemies (Carpenter et al. 2007; Grové et al. 1999; Newton 1988) and sterile insect technique (Carpenter et al. 2007) are employed to suppress FCM infestations in fruits, particularly citrus. However, information on the alternate management of FCM on deciduous fruit is lacking.
Initial research on the biological control has been completed for use against FCM in deciduous fruit. These studies have found that entomophathogenic fungi (EPFs) show promise to cause significant mortality against FCM (Begeman 2008, Goble et al. 2011, Steyn, pers. comm.). Also, entomopathogenic nematodes (EPNs) were found to give 93% control against cocooned pupae and emerging adults of FCM, in laboratory bioassays (Malan et al. 2011). The most efficient natural enemy for suppression against FCM is the egg parasitoid Trichogrammatoidea cryptophlebiae, which has been found to parasitize up to 80% of FCM eggs without additional augmentative releases, while an efficient larval parasitoid has also shown promise as biocontrol agent (Grout & Moore 2015). However, not much research was conducted in the Western Cape Province in this regard and we do have an inventory of parasitic wasps known to attack FCM. Entomopathogenic fungi-, nematodes and egg parasitoids will be assessed in the laboratory and field experiments for their efficacy on FCM, to enable the integration of these organisms into a management strategy. These biological control agents are valuable in targeting particularly the immature stages of FCM, and can therefore offer solutions to preventing the build-up of pest populations early in the season.

REFERENCES
Begemann, G. 2008. The Mortality of Thaumatotibia leucotreta (Meyrick) Final Instar Larvae Exposed to the Entomopathogenic Fungus Beauveria bassiana (Balsamo) Vuillemin. African Entomology, 16, 306-308.

Bloemfield T. 1989. Economic importance of false codling moth, Cryptophlebia leucotreta, and codling moth, Cydia pomonella on peaches, nectarines and plums. Phytophylactica 21: 435-436. CAB 2007. Crop protection compendium: Global module. Commonwealth Agricultural Bureau International, Wallingford, UK.

Carpenter JE, Bloem S & Hofmeyr H. 2007. Area-wide control tactics for the false codling moth Thaumatotibia leucotreta in South Africa: a potential invasive species. In: Vreysen MJB, Robinson AS & Hendrichs J. (editors). Area-Wide Control of Insect Pests from Research to Field Implementation. Dordrecht, The Netherlands: Springer. p. 351-359.

Goble, TA. , J.F. Dames, M.P. Hill & S.D. Moore. 2011. Investigation of native isolates of entomopathogenic fungi for the biological control of three citrus pests, Biocontrol Science and Technology, 21:10, 1193-1211, DOI: 10.1080/09583157.2011.608907

Hofmeyr, JH & Pringle, KL. 1998. Resistance of false codling moth, Cryptophlebia leucotreta (Meyrick) (Lepidoptera: Tortricidae), to the chitin synthesis inhibitor, triflumuron. African Entomology 6: 373 – 375.

Malan, AP., Knoetze, R., Moore, SD. 2011. Isolation and identification of entomopathogenic nematodes from citrus orchards in South Africa and their biocontrol potential against false codling moth. Journal of Invertebrate Pathology 108: 115 – 125.

Venette RC, Davis EE, Da Costa M, Heisler H & Larson M. 2003. Mini risk assessment. False codling moth, Thaumatotibia (=Cryptophlebia) leucotreta (Meyrick) (Lepidoptera: Tortricidae). Department of Entomology, University of Minnesota.