False Codling Moth: The citrus headache
By Dr. Gulu Bekker Head Technical | Western Cape
False Codling Moth, Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae) is native to sub-Saharan Africa, and was first described from samples collected in the Pretoria area. It is considered a major pest in the citrus industry. False codling moth (FCM) is recognised because of its phytosanitary risk status, which hinders foreign market exports for South Africa, as entire consignments can be rejected. FCM infests a broad range of fruit-bearing plants, including 80 different species of trees and shrubs, citrus, avocadoes and stone fruits - all economically important crops. Additionally, FCM larval feeding can affect fruit at any stage during ripening; causing early fruit drop, further reducing yields.
A) Beauveria strain RPM02 Larva, approx. 5 days after death; B) Metarhizium strain ICIPE07 Larva, 3 days after death; C) Metarhizium strain ICIPE69 Larva, approx. 7-14 days after death; D) Metarhizium strain ICIPE78 Larva, 3 days after death (Credits: F. Du Preez)
Life cycle and temperature
Temperature plays a major role in the duration of life cycle developmental stages, from egg to the pupal stage. Egg incubation varies between seasons ranging from 9 - 12 days in winter and 6 - 8 days in summer. Larvae spend four out of its five larval stages within the fruit itself. The larvae will only exit the fruit during the final instar stage, after which it pupates in the soil, directly below the host plant. During the pupal stage, development can take anywhere from 21 - 80 days without diapause. Adult moths have been reported to have a lifespan of 2 - 3 weeks in the field.
Resistance and EPFs
FCM is known to have developed resistance to the majority of insecticides, and with strict regulations regarding chemical residues, the need for biological control methods has increased. Biological control includes the use of entomopathogenic fungi (EPF). Entomopathogenic fungi is a widespread, natural component in soil ecosystems and has been found to regulate soil-dwelling insect populations. EPFs have been reported to be successful in the control of various citrus pests. The benefits of using EPFs includes the lack of toxic residues and its negligible effect on non-target organisms and the environment. The order Hypocreales, includes some of the most versatile and widely used fungal and biocontrol agents, such as the genera Beauveria and Metarhizium.
A) Beauveria strain RPM02 Pupae, approx. 3 days after death; B) Metarhizium strain ICIPE78 Pupae, 3 days after death (Credits: F. Du Preez)
Integrated pest management
When managing a pest it is important to have access to solutions for all the life stages of the pest. RealIPM offers a range of strategies and products to manage the different life stages of FCM in our agricultural landscapes. This includes a variety of specific EPF strains for specific life stages, applied as a cover spray or soil application, a range of contact biopesticides, attract and kill options as well as mating disruption (traps and lures). Please visit our website to find out more about our approach and products or to contact one of our expert technical advisors, for a free on-farm consultation.
References
Available on request