IntroductionFalse codling moth (FCM), Thaumatotibia leucotreta, is a pest of citrus fruit, macadamias, avocadoes, stone fruit, peppers and various other crops, in sub-Saharan Africa. The adult female will lay her eggs singly on fruit. Larvae will penetrate into the fruit within minutes of hatching (Fig. 1). Infestation will cause fruit to drop off the plant. FCM can cause substantial crop losses. Undetected infestation shortly before harvest can cause decay of fruit once it has been packed and shipped to export markets.

Due to its cryptic habits (as an internal feeder) and its capacity to develop resistance to chemical insecticides, effective control of FCM is difficult to achieve. Most chemical insecticides are also highly detrimental to the effective egg parasitiod of FCM, Trichogrammatoidea cryptophlebiae. Moreover, their use can lead to outbreaks of other important pests.

What is CRYPTOGRANTM?CRYPTOGRANTM is a naturally occurring indigenous pathogen of FCM, called the Cryptophlebia leucotreta granulovirus (CrleGV-SA) (Fig. 2). Citrus Research International (CRI) has conducted years of research in testing and developing the virus as a biological control agent of FCM. Consequently, it was registered for use on citrus in South Africa in 2004 and on avocadoes in 2009 (L7598: Act 36 of 1947), after approval by the Departments of Agriculture, Health and Environmental Affairs. CRYPTOGRANTM is commercially produced by River Bioscience, a company owned by the Southern African Citrus Growers’ Association (CGA).

Figure 1. A neonate false codling moth larva penetrating the rind of a fruit.

Figure 2. Transmission electronmicrographs of CrleGV (active ingredient of CRYPTOGRANTM): cross-section (a) and transverse section (b).

(a) (b)

Figure 3. A one litre bottle of CRYPTOGRANTM

Further informationFor further information on CRYPTOGRANTM and River Bioscience (Pty) Ltd, contact:The General Manager, River Bioscience, PO Box 20388, Humewood, 6013Tel : +27 (0)41 583 5524/3464Fax : +27 (0)41 583 3657Email : info@riverbioscience.co.za

Biological control of the false codling moth

It is available in a suspension concentrate in 1-litre volumes (Fig. 3). Each millilitre of product contains a total of at least 50 billion virus particles, known as occlusion bodies (OBs). Each litre of product is sufficient to spray around 1 ha of mature orange or avocado trees.

How does CRYPTOGRANTM work?When CRYPTOGRANTM is sprayed onto a crop, FCM larvae will ingest the virus particles, potentially even before they begin to actively feed (Fig. 4). The protec-tive protein layer of the virus will dissolve in the highly alkalinic midgut of the larva. Virions will be released and absorbed through the microvilli of the midgut. Primary replication of the virus will take place in the nuclei of the midgut cells. The virus will eventually infect the entire body of the larva, killing it. The flac-cid larva will spontaneously rupture, releasing millions of virus particles back into the environment, ready to be ingested by other larvae. Well before death occurs, viral infection will result in a cessation of feeding and even cause larvae, which have begun penetrating the fruit, to return to the surface of the fruit.

How well does CRYPTOGRANTM work?Dozens of field trials have been conducted with CRYPTOGRANTM against FCM on various citrus cultivars throughout South Africa, since 2000. Sprays applied in late November or early December, timed to coincide with a peak in FCM activity have provided the greatest control of the pest. In semi-commercial trails on navel oranges, CRYPTOGRANTM reduced FCM infestation of fruit by 70% and more for as long as 17 weeks. This duration of control with an insect virus on fruit crops is unprecedented. It is believed that the reason for this incredible persistence on navel oranges is that CRYPTOGRANTM is protected against harmful UV-irradiation (and possibly other climatic factors too) in the exact region where the vast majority of FCM larvae penetrate the fruit i.e. the navel end.

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Figure 4. The life cycle of CrleGV-SA (active ingredient of CRYPTOGRANTM) in a false codling moth larva.

How safe is CRYPTOGRANTM?The word “virus” might immediately conjure up visions of uncontrollable and severe epidemics. However, CRYPTOGRANTM is completely safe for human beings and all other forms of life (except FCM). Trials conducted by Onderstpoort Veterinary Institute with mice, demonstrated no negative responses whatsoever even after ingestion of relatively large volumes of highly concentrated CRYPTOGRANTM.After non-target effect testing by CRI for registration purposes, CRYPTOGRANTM was referred to as “probably the softest pesticide tested with regard to its toxicity to natural enemies”. Consequently it has been categorised as “Harm-less” against natural enemies considered important in the citrus ecosystem.As the active ingredient of CRYPTOGRANTM is a naturally occurring indigenous pathogen, it can in no way be viewed as an environmental contaminant.

Other advantages of using CRYPTOGRANTM

Apart from being an effective, persistent and safe treatment for controlling FCM, there are a number of other advantages to using CRYPTOGRANTM

• It is completely compatible with an Integrated Pest Management (IPM) programme or even a biological control programme. No repercussions of other pests will occur as a result of its use.• Unlike most other biological control agents, it is also completely compatible with a chemical control programme.• CRYPTOGRANTMis certified for organic farming.• There is no maximum residue level (MRL) for fruit going to either export or local markets, therefore no pre-harvest interval is required and no residue problems can occur.• CRYPTOGRANTM is a naturally occurring indigenous pathogen, the develop- ment of resistance to it by FCM is highly improbable.• Unlike other products, CRYPTOGRAN™ has the unique ability to replicate in an orchard after application – its impact potentially being way more than just that of the initial application.• As it is naturally occurring and completely safe, the spraying of CRYPTOGRANTM is an environmentally responsible means of pest management.• Laboratory and field trials show that it is compatible with other pesticides such as pyriproxyfen, methiadathion, abamectin, mancozeb, benomyl, oil, bromopropylate, methomyl, strobilurins and others.

Application of CRYPTOGRANTM

CRYPTOGRANTM is registered to be sprayed at 10 ml per 100 litres of water with 0.25% molasses and a wetter, as a full cover film spray. Due to the ultra-violet sensitivity of insect viruses, it should be applied during the late afternoon or evening. Being in suspension, CRYPTOGRANTM should be well shaken before use.At least two applications of CRYPTOGRANTM per orchard per season are recommended on navel oranges and avocadoes (Fig. 5). The first should be targeted against, or shortly after, the first major generational peak of FCM, which usually occurs during late November or early December throughout most of South Africa. This peak can be detected by using Lorelei® pheromone traps. The purpose of this application is not only to reduce pre-harvest fruit loss, but to ensure a lower and more controllable level of FCM before harvest. There-fore, this first application would even be justified if trap catches do not exceed the threshold for action (i.e. 10 or more moths per trap per week). The timing of this application can be delayed. However, sprays applied during November and December have been shown to be significantly more effective than those

made during February or March. Any application should be applied shortly after a flight peak. As many sprays as necessary should be applied. However, this is usually not more than two or three per season on citrus and avocadoes.The last application should be made 3-4 weeks before harvesting begins, for the purpose of reducing the incidence of post-harvest problems. A pre-harvest application should be considered for all orchards of FCM-susceptible cultivars, even if FCM levels are low. Remember that the purpose of this application is to bring the possibility of post-harvest problems occurring, as close to nil as possible. Bear in mind that no product, no matter how effective, is capable of providing total control of FCM. It is also important to realise that CRYPTOGRANTM cannot be used effectively as a late-season corrective option against high levels of FCM. FCM must already be under good control in order to enjoy the post-harvest benefit of a pre-harvest CRYPTOGRANTM spray.CRYPTOGRANTM can be used in conjunction with other modes of controlling FCM, such as mating disruption, the sterile insect technique and attract and kill.

On which crops can CRYPTOGRAN™ be used?FCM is a fruit pest on a range of cultivated crops. These include citrus, avocadoes, macadamias, peppers, grapes (Fig. 6), stone fruit, persimmons and pomegranates. Currently, Cryptogran™ is registered for use on citrus and avocado crops. However, trials have also been conducted on peppers and grapes, showing significant control of FCM.

Storage of CRYPTOGRANTM

CRYPTOGRANTM should be kept refrigerated at around 4°C. Under these conditions, the shelf life has been confirmed to be at least 18 months.

Other River Bioscienceproducts• M3 Fruit fly bait station• Sensus fruit fly traps with male and female lures

Figure 6. False codling moth larva feeding inside a grape.

Figure 5. False codling moth infestation of navel oranges and the recommended timing of CRYPTOGRANTM applications: One-spray (blue) vs two-spray (red) approach. An additional spray in February would have reduced FCM levels even further.

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