FALSE CODLING MOTH (FCM)

Transcription

1 FALSE CODLING MOTH (FCM) What is FCM? Thaumatotibia leucotreta also known as False Codling Moth or valskodlingmot is a phytosanitary pest which is indigenous to Africa. It has an extremely wide host range, including 24 commercial and 52 wild host plants. Biology & lifecycle FCM is subtropical species with a lower development threshold of ±12 C. Moths have a fecundity of 460 eggs per female at 25 C and 0.4 eggs at 10 C. The lifecycle spans 32 days at 26 C and 114 days at 13.7 C. Moths have no dormant stage with approximately six overlapping generations. Adult flight peaks usually occur around November and January/February (see diagram below). Damage Newly-emerged larvae enter fruit at any place on the fruit, although there is a tendency to enter at the stalk end. They tunnel to the centre of the fruit and feed mainly around the stone or core. Dark brown granular excreta is produced in the feeding area. Prior to the emergence of the mature larva from the fruit, the excreta may be pushed out of the exit hole.

2 Damage to look out for: How to identify FCM (Thaumatotibia leucotreta) from related pests Codling moth (Cydia pomonella) Adult Adult Strongly dimorphic meaning that males and females can be clearly differentiated: male wingspan 15-16mm, female wingspan 19-20mm. In both sexes the fore wing pattern consists of a mixture of grey, brown, black, and orange-brown markings, the most conspicuous being a triangular marking in the outer part of the wing, against the hind margin, and a crescentshaped marking above it. Wingspan 14-22mm. Blackishbrown colouration on wings, suffused with ash-grey, transverse dark bands and a large copperyyellow marking near the tip. Hind wings are brown.

3 Oriental fruit moth (Grapholita molesta) Pear leafroller (Epichoristodes acerbella) Adult Wingspan 10-16mm. Adult moth is 6-8mm in length. Fore wings are greyishbrown with distinct light and dark transverse bands. Key: Adult moth identification Adult Wingspan 14-24mm. Fore wings are light-ochre in colour, often with a dark band towards the distal edge. Hind wings are greyish-white.

4 FCM Larvae Oriental Fruit Moth Larvae Larvae can measure up to 15mm in length. Young instars are yellowish-white with dark spots. Full-grown larvae are pink or bright red. Head, prothoracic shield and pinacula are yellow-brown. Opaque anal comb present Larvae reach 12mm in length. Body is pink to almost red. The head, prothoracic shield and anal shield are brown. Opaque anal comb present. Mediterranean fruit fly larvae Codling Moth Larvae Larvae can measure up to 20mm in length. Young instars are whitish but later appear pale pink, with dark pinacula. The head and prothoracic shield are brown, and anal shield yellowish-brown. Anal comb absent. White banana-shaped eggs (about 1mm in length), laid beneath the skin of the fruit, hatch into characteristic maggot-shaped larvae which are broad and truncate in the rear and taper to a point in front. Mouthparts at the front tip are small and initially reddishbrown, later becoming black. Larvae are translucent white on hatching, and creamcoloured when full-grown (about 8-10mm in length).

5 Pear leafroller larvae Larvae can reach 18mm in length. Body is yellowish-green with a darker line on the dorsal surface and two lateral yellow lines, head dark brown. Anal comb present and transparent. Size comparison

6 Key: Larval Identification Preservation of FCM larvae: *Microscope needed Pour boiling water over the larvae and leave for 5min Remove the larvae from the water Cover the larvae with 70% alcohol Label the bottle with details such as date, farm, cultivar, fruit kind, orchard number etc. Submission for ID at Stellenbosch University: Anal comb For more information contact Corey Bazelet or Pia Addison

7 FCM CONTROL GUIDELINES Monitoring It is difficult to manage what is not measured. Fruit damage assessments and pheromone traps supply information that is vital in determining control strategies. Control strategies are best decided on at the end of a season using fruit infestation data gathered just before or at harvesting. Scouting (fruit damage assessments) and the use pheromone traps to gather pest management information is described in detail below. This system is based on the monitoring system developed for apples (reference: L BROWN & KL PRINGLE. Monitoring system for pests on pome fruit. DFPT Research Pamphlet). Traps should be monitored and serviced weekly. No level of moth catches will result in disqualification of orchards, but the monitoring data must be used for management purposes, such as seasonal comparisons, treatment prioritisation of orchards and timing of treatment application. Note that in orchards where mating disruption is utilised the trap results are less reliable. Therefore the information gained from scouting and fruit damage assessments is very important for the planning of future control strategies. Data must be recorded and safeguarded for inspections. Fruit damage assessment Monitoring procedure Orchards should be divided into blocks of ± 2 hectares (ha). In each± 2 ha block select 25 trees, evenly spaced throughout the block. Mark these trees and use every time for pest monitoring. Pheromone traps 10 fruit from each of the 25 marked trees should be visually inspected. Any fruit that shows any form of damage should be cut in such a way that any FCM larvae can be identified. All fallen fruit from sample trees should also be cut and inspected for FCM larvae. This should be done every 2 weeks and specifically after each FCM generation. FCM pheromone monitoring traps should be placed in the centre of each monitoring block and at a density of at least one trap per 2 ha and at least one trap per orchard. Placement of the trap should be in the top ¼ of the tree. Pre-harvest fruit damage assessment This pre-harvest fruit damage assessment should take place within 7-10 days of harvest. Follow the procedure listed above

8 Control options As many as possible of the developmental stages of FCM should be attacked in an integrated management strategy to control FCM populations, thereby reducing fruit damage. These guidelines will summarise the tools currently available and registered under Act 36 of 1947 for control of FCM in South Africa. Since these guidelines cover stone fruit as a group it is the responsibility of growers and advisors to ensure that products used are registered on their specific crops. Egg No insecticide currently registered against FCM on stone fruit has an effect on FCM eggs. Augmentative releases of the naturally occurring egg parasitoid, T. cryptophlebiae has shown to successfully decreased population levels of FCM on citrus and could be considered for use on stone fruit. 1st instar larvae This is the most sensitive stage in the life cycle of FCM. As a result, a large number of insecticides are registered and recommended against this stage. For insecticides listed as contact or stomach insecticides to be effective, larvae have to ingest or physically come into contact with the active. The window period between egg hatching and larval penetration of the fruit is the only time during which larvae could come into contact with insecticides. Timing of application of these products is therefore critical. Pyrethroids: (contact and stomach insecticides) Beta cypermethrin Alpha-cypermethrin Lambda-cyhalothrin Zeta-cypermethrin Cypermethrin Pyrethroids shut down the nervous system of insects by preventing the closure of the voltage-gated sodium channels in the axonal membranes. Pyrethroids are registered to be applied as full cover sprays six to eight weeks before harvest, depending on cultivar, and repeated every 14 days. It is important to note that this group of insecticides is potentially toxic to natural enemies of other pests and should be used judicially to prevent pest repercussions.

9 Diamides: Altacor - Chlorantraniliprole (stomach and contact insecticide) Chlorantraniliprole inhibits muscle contractions and causes death in insects by paralysis. It is virtually harmless against beneficial insects and humans. A maximum of 2 full cover foliar applications are allowed at 14 day intervals per season, starting when trap catches indicate an infestation of FCM. Spinosyns: Delegate - Spinetoram (stomach and contact insecticide) Spinosyns affect the nervous system of the insect by targeting the nicotinic acetylcholine receptor. Delegate is registered to be applied as a full cover spray, one to three times per season. Commence applications 6-8 weeks prior to harvest or when regular moth catches are recorded. Repeat applications against FCM at fourteen (14) day intervals. Oxadiazines: Steward Indoxacarb (stomach and contact insecticide) Indoxacarb blocks the nerve sodium channels in nerve cells causing paralysis and death. Apply as full cover spray when moth catches in pheromone traps indicate an infestation of False Codling Moth. Reapply at 10 day intervals if necessary. Avermectins: Warlock - Emamectin benzoate (stomach insecticide) Emamectin blocks the transmission of electrical activity in insect nerve and muscle cells causing paralysis of neuromuscular systems. Apply Warlock as a full cover spray. Start application when first sign of pest presence is observed. Repeat at 7 to 10 day intervals as part of an IPM system. Do not apply more than 4 times per season. Neonicotinoids + Benzoyl ureas Cormoran Acetamiprid + Novaluron (contact and stomach action as well as chitin synthesis inhibition). Neonicotinoids are competitive modulators of nicotinic acetylcholine receptors. Overstimulation of these receptors (in the nervous system) leads to paralysis and death. Benzoyl urea inhibits chitin biosynthesis blocks the production of chitin, an important component of an insect s cuticle. Moulting cannot take place and eventually the insect dies. Apply Cormoran as a full cover spray when a first sign of pest pressure is observed. Apply only once per season. Bacterial insecticides: BeTaPro - Bacillus thuringiensis

10 BeTaPro has to be ingested to be effective. Ingestion results in formation of pores and channels in the gut membrane, causing destruction of epithelial cells. According to the registration holder a minimum of three full cover sprays have to be applied commencing when pheromone traps dictate control. The product is UV sensitive and it is recommended that it be applied during afternoons or evenings. Considering that granulovirus is UV sensitive and has a low dose-response, application of virus products at shorter intervals and lower applications rates rather than high rates once or twice a season is advisable. Registered labels of some of the registered products have been amended to reflect this statement. Entomopathogenic fungi: Viruses: Cryptophlebia leucotreta granulovirus (CrleGV) There are currently three granulovirus products registered against FCM on stone fruit, Gratham, Cryptex and Cryptogran. Timing of application of granulovirus products is critical. The only developmental stage targeted by virus applications is the 1st instar larva. After hatching, the neonate larva ingests virus particles that infects the whole body and eventually kills the insect. Apply a full cover spray at peak egg hatching. Application of the virus 1 to 2 weeks after peak moth flights (determined by catches in pheromone traps) will coincide with peak egg hatching. Granulovirus is UV sensitive. It is therefore advisable to apply virus formulations in the late afternoon or evening. Eco Bb, Broadband - Beauveria bassiana The spores of B. bassiana germinate and secrete enzymes which weaken the insect cuticle. This leads to water loss and death of the insect. The fungus continues to grow, feeding on the internal organs. B. bassiana spores do not have to be ingested. Contact with spores is sufficient to cause infections. Apply as full cover spray at first sign of FCM and repeat at least 3 times during the season. Larvae & pupae in soil Orchard Sanitation Nothing is currently registered for the control of larvae and pupae in the soil but the role of ants, entomopathogenic nematodes and fungi in the soil on mortality of FCM should not be underestimated. In addition to that, proper

11 sanitation will go a long way in reducing the number of larvae from pupating in the soil and should form the basis of integrated control of FCM. Orchard sanitation entails the collection and removal of all dropped fruit and all hanging fruit, which shows any sign of damage or infestation. Orchard sanitation must be conducted weekly and continue up to the end of harvesting has been completed, at which time the orchard must be cleared of all the current season s fruit (both fruit on the tree and fallen fruit). Removed fruit must be removed from the orchard and destroyed in such a way that it does not allow re-infestation (bury deeper than 30 cm). Alternative hosts FCM has a very wide host range. From a practical point of view all berries, nuts and fruit, wild and domesticated, should be considered potential hosts. Controlling FCM in these hosts during the season and especially during the off-season will reduce pest pressure. Cutting down alternative host should be considered. Adult No cover spray currently registered will control the adult FCM moth. There is unconfirmed evidence that B.bassiana applications might have an effect on adult moth mortality. There are two area wide options available to manage adult moth populations namely mating disruption (MD) and Sterile Insect Technique (SIT). Mating disruption Mating disruption (MD) is a technique where large quantities of female sex pheromone are released to inhibit the ability of males finding females. The species specific pheromone that females excrete to attract males is identified, synthesized and formulated into a matrix that facilitates a relatively even release of the pheromone. The pheromone/matrix is employed in orchards to disorient males. Confusing males in this manner prevent mating or result in late mating of females. Less viable eggs will be laid, thereby reducing population numbers. MD works best when applied over a wide area where populations are relatively small. It is critical that MD products are applied at the beginning of the season, before the first flight, when population levels are still low. The concentration of pheromone is lowest on the edges of orchards making mating more likely on the edges. It is therefore advisable to use MD on as big an area as possible.

12 Pheromone is heavier than air and should be applied as high as possible in trees - at minimum, in the top third. The same pheromone used in MD is also used in pheromone traps. Trap catches will therefore be affected or shut down in orchards where MD is used. Trap shut down is an indication that MD is working and is good enough reason to continue using pheromone traps in MD orchards. However, scouting (physical monitoring of fruit) on a regular basis is the only reliable way to determine the success of control strategies in MD orchards. There are currently four MD products registered against FCM on stone fruit: Checkmate FCM-F is a microencapsulated sprayable formulation that is applied every 21 to 28 days. It can be applied as a low volume spray in tank-mix with fruit fly baits. First application should be applied before the first flight at the beginning of the season i.e. beginning of November. Isomate FCM consists of a polyethylene tube containing pheromone. Dispensers have to be applied at the beginning of November at a rate of 600 dispensers per hectare. X-Mate F.C.M. is a ready-to-use, pheromone based, mating disruption product. Use X-Mate F.C.M dispensers per hectare per production season irrespective of tree density. Attach dispensers to the tree-clip (supplied) and apply the tree-clip with dispenser to a lateral branch in the top 1/3 of the tree. Hang dispensers evenly throughout the orchard. RB Splat FCM is an amorphous polymer matrix that releases pheromone. Apply 1000g per hectare at 2g per point source to the top third of the tree. Reapply after 10 to 12 weeks. Sterile Insect Technique The Sterile Insect Technique (SIT) is a method to control or eradicate an insect species by releasing large numbers of sterile or partially sterile individuals of the same species into an area. Sterile males mate with wild females resulting in no offspring, thus reducing the population. Moths are mass reared and sterilised by gamma radiation. The current accepted ratio of sterile released moths to wild moths is 10 to 1. To achieve this ration, SIT is almost always dependent on other methods of control to reduce the wild population. It is compatible with most of these methods. SIT, like MD an area wide pest control strategy and to get the best possible effect from these strategies, it often has to be

13 employed as a coordinated effort by a number of growers in an area. Acknowledgements: T Labuschagne for his contribution to the drafting of the control options. Dr Shelley Johnson: HORTGRO Science and Department of Conservation Ecology and Entomology, University of Stellenbosch for the extracts out the Quick identification guide for key phytosanitary pests of South African deciduous fruit compiled by Dr S Johnson. The following people are thanked for their photographic contributions: Dr P Addison, Dr T Blomefield, J Coetzee, Prof H Geertsema, Dr A Manraknnam, C Nyamukondiwa, Dr K Pringle and Dr A Timm (Tortricid moth identification keys. DISCLAIMER

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