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Unwelcome newcomer gets the pheromone treatment - HortResearch

More about the Guava Moth Fruit Driller

FRUIT-DRILLER CATERPILLAR THREATENS FRUIT HORTICULTURE

A new insect invader from across the Tasman threatens to produce widespread damage to fruit tree crops in New Zealand. The guava moth (Cosinoptycha improbana) first began to attack tree crops in Northland about 3 years ago. Although called the guava moth, in New Zealand it is infesting a wide variety of fruit and nuts, including plums, feijoas, nashi, citrus, loquats, macadamias and guavas. It therefore deserves a new name, thus the suggestion of "fruit-driller caterpillar". For soft fruit such as plums, there is little external evidence of infestation until someone bites into a grub-infested fruit.

In contrast to Australia where the pest is of minor concern, complete destruction of infested orchard crops has been observed in New Zealand. As with the possum invasion, the fruit drilling caterpillar is behaving quite differently in this country, and has the potential to produce a population explosion and spread across New Zealand (in Australia it occurs as far south as Tasmania, so is likely to adapt to colder areas in NZ). The population explosion is likely to result from the caterpillar targeting different fruit that ripen throughout the year, allowing many breeding cycles. As well, the sale of infected fruit in population centres such as Auckland creates an ideal situation for the rapid spread of the guava moth. Infestation of crops in Northland is patchy at present, indicating that there may still be time before the insect becomes a serious pest in New Zealand, providing action is taken NOW. The procrastination that has happened in the cases of the varroa bee mite and the painted apple moth in Auckland vividly demonstrates the dangers of failing to act in time.

However, no apparent attempt at eradication, or even control, has been made. Organic orchards are at particular risk, due to the lack of chemical spraying programmes. Even chemicals are unlikely to control the pest for long, as resistance to them will probably develop rapidly in this moth, due to the need for continuous spraying programmes. The moth threatens the newly developing macadamia industry in New Zealand, as one of the biggest advantages it has over its larger Australian and Hawaiian counterparts is the ability to grow macadamias organically in NZ.

A valuable control method, acceptable to organic growers, would use lures containing pheromones. These natural chemicals are produced by the female guava moth to attract males for mating. Traps containing these pheromone lures can disrupt the mating ability of the moth. A similar method, using different pheromones, is currently employed to control codlin moth. In spite of Hort Research identifying the guava moth pheromones, there is apparently no plan at present to use these pheromones for control. To our knowledge, all the pheromone traps produced by Hort Research are only being used to monitor how far the guava moth is spreading.

For more information telephone Dr Gordon Lees, Chairman, Northern Region Branch, New Zealand Tree Crops Association. Email us.

driller larva

moth, wings spread

moth, wings folded

Photos courtesy of the National Plant Reference Laboratory, MAF.

PEST ALERT - THE GUAVA FRUIT MOTH ATTACKS NORTHLAND ORCHARDS

An Australian pest, probably wind blown, evidently arrived in Kaitaia up to 5 years ago. Coscinoptycha improbana, one of a number of species with the common name of guava fruit moth, was first found to be attacking feijoas but according to Dave Austin who runs a nursery in Kaitaia, is now a pest of guavas, especially the tropical guava, some varieties of peaches, pears, nashi and apples. It has also been shown to attack citrus, plums and loquats. As some timber trees are in the same genera as some of the fruit attacked, there is the possibilities that fruit of these, e.g. the pohutukawa may also be susceptible. The moth has subsequently spread to the Kerikeri area where it is attacking citrus. Within the past month it has been identified as a boring insect on organic macadamia orchards. Not something expected of a moth attacking soft fruits! The pest can totally destroy the nut.

Treecroppers were an essential part of the chain that led to its identification as a macadamia pest. Eileen Welch in Kaikohe noticed the pest in her macadamias and handed on a sample to the North Island VP of NZTCA. Diana Loader on her recent trip throughout Northland. Diana passed it on to member Derek Craig in Auckland who used his contacts to have it identified by Hon Research. The larval form is small, growing to about 6 mm (¼ inch) and becoming pink as it matures. The moth probably has a short life of a few days before laving eggs. We have not, as yet, been able to establish what the moth looks like. The larvae and moth are thus susceptible to control for only a short period. Small exit holes have detritus similar to codlin moth. It appears that fruit subject to attack can develop off flavours. In the north, multiple cycles of moths are likely to occur during the year.

In Australia it is regarded as a garden pest only, but part of this reasoning may be because of the lower number of organic orchards. Macadamias in Australia are difficult to produce organically due to the number of pests attacking them, and hence the spraying programme used there may have incidentally kept the guava fruit moth under control. In NZ the relative lack of pests has been seen as a commercial advantage, allowing organic production. Hence the need to control this insect. BT spray may be successful, which would be acceptable to organic growers. A small amount of work has evidently been done on developing a pheromone attractant for the moth, but Hort Reseach should be encouraged to upgrade the resources spent on controlling the guava fruit moth. At present, research on the pest is essentially non-existent and MAF has shown little interest in monitoring its advance or range of crops attacked. MAF has given minimal media coverage to the problem and have thus failed to alert growers of the moth's potential for causing damage. This is one area that treecroppers can act as eyes for early warning. The spread south needs to be monitored, as in Australia the insect is found as far south as Tasmania and hence much of NZ is potentially susceptible. The movement of crops, such as macadamias, south for processing could encourage its geographical spread.

If you find the insect on your fruit, let MAF or myself know (Email us) so that the branch can act as a central collection point for data on this pest We would also ask growers of avocadoes and olives to alert us to any attacks on these crops. If any members grow timber or native trees, please look for infestations in their fruit.

Gordon Lees

Guava moth (fruit driller caterpillar) update.

Monitoring of the guava moth in Kerikeri is continuing with little evidence of control methods being introduced. Hort Research in Kerikeri is carrying out trials with different pheromone mixtures in different positions in a mixed orchard in Kerikeri. Traps have been found to contain between 1 and 6 adults.

In this orchard, fruit lower on the tree seem to be more seriously infected than those higher up. Infected loquats were removed from trees in November and placed in green and black plastic bags and left in the sun to cook. The black plastic bags had holes bored through the bags as the caterpillars apparently escaped! Satsuma plums are currently being eaten with most damage occurring around the stone, although the caterpillar has yet to enter the stone. Macadamias are also infected now, some varieties more so than others, but did not appear to be infected in November. The caterpillars are just beginning to infect feijoas. Other growers in Kerikeri also continue to have their orchards infected by the moth.

How much longer before the moth reaches south to other fruit growing regions? This spread will only be helped by fruit being transported to population centres for sale. There is a difficult situation here. If the moth is declared a notifiable pest, then Northland fruit growers will be denied their main markets and export markets may also become affected.

The Northern Region TCA committee are continuing to try to get action to control damage to treecrops caused by the guava moth caterpillar in Northland. It is a slow, time consuming business with some fish-hooks to overcome. To help determine the when might be the best period(s) to attack the insect, we need some idea of its life cycles (e.g. does it ever have a dormant period when it is not attacking some crop or other?). We need a volunteer in Kerikeri and one in Kaitaia to monitor the infestations of the guava moth caterpillar in fruit in Northland. This would involve ringing a set group of NZTCA members in these areas (or other suitable people with treecrops) once a month to determine when various treecrops become infected, and to gauge the seriousness of the infestations. Caterpillar counts would also be required. Full details will be worked out in association with qualified entomologists to ensure that any data collected is maximally useful. It will also become crucial to make sure it is the guava moth causing the damage, so some infected fruit would also need to be collected, in order to send to qualified entomologists for positive identification. This is particularly important if new crops appear to have become infected. This is a chance for Treecroppers to make an important contribution to the control of a fruit pest. While no doubt the moth will eventually reach other areas in NZ, Northland is where it is currently causing the most damage - so any volunteers? Contact the Chairman or Email us.

Gordon Lees

FOLLOWUP ON THE GUAVA MOTH.

A Kerikeri orchard has reported a close to 100% loss of its apple crop with infestation which has also affected Paragon peaches. The apples are misshapen and riddled with small insect tracts but with no insects apparent. This experienced orchardist has never since this type of damage before. While the tracts are smaller than those usually caused by the guava moth, the possibility exists that the guava moth does not find apples a suitable host and the caterpillars die before reaching maturity. MAF Biosecurity have been informed and will be checking on this crop. Eileen Welch reports that a grub found in one of her bananas appeared to be a guava moth caterpillar (also supported by HortResearch worker, Ted Dawson). The grub has been sent to HortResearch in Lincoln for positive identification. Last year, an unknown insect evidently affected casimiroas in Northland. If you see damage to your crop this year, please keep samples for identification, and tell us. The branch will make sure it is identified. Up to 50% of a box of plums sent to me from Kerikeri and checked for infestation prior to forwarding were found to be infested by the guava moth. Obviously, it is going to be very easy for this fruit drilling caterpillar to spread to other fruit growing regions within NZ. Keep the reports coming, and if possible take photographs of the damage and estimate the percentage of the crop affected. It is vital that we have as much ammunition as possible to convince the appropriate authorities that the guava moth (fruit driller caterpillar) is a serious pest for fruit and nut crops in NZ.

Gordon Lees

GUAVA MOTH - REPORT ON MEETING HELD AT HORTRESEARCH STATION IN KERIKERI NOVEMEBR 2ND 2001

The guava moth (Coscinoptycha improbana) is currently infecting a range of fruit crops in Northland in an area stretching from Kaitaia to Kerikeri. Plant hosts attacked by the moth include feijoas, nashi pears, guavas, citrus, peaches, plums and loquats. A new surprising host not known to be infected by the moth in its home country of Australia is the macadamia. Control of the moth poses particular problems for organic growers. At the Kerikeri HortResearch Centre on the 2nd November, representatives from interested fruit and nut growers, the Northern Regional Council and the NZ Tree Crops Association met with scientists and management personnel from MAF Biosecurity and HortResearch to discuss the problems posed by the guava moth.

MAF Biosecurity Officer, Dr Barney Stephenson, outlined the role of MAF Biosecurity in determining the threat posed by new plant pests. He stated that their initial assessment was that the guava moth (Coscinoptycha improbana) would be of minor importance and that eradication is unlikely. In effect, irrespective of any deficiencies in their past assessment of the risk posed by this pest, they are highly unlikely to become involved in future actions involving this pest. Some lessons need to be learnt concerning the rapidity to which the decision and information concerning a new pest is passed on to interested parties. The guava moth is but one of 20 to 30 new pests identified each year by MAF Biosecurity.

Dr Max Suckling of HortResearch then outlined the development and initial trials of a pheromone mixture and its potential use in monitoring the severity of infestations and the spread of the moth. HortResearch have identified the pheromone present in the guava moth (a mixture of two compounds in a 95:5% ratio) and have undertaken preliminary work on the effectiveness and specificity of this mixture for the guava moth. The pheromone appears to be a mixture of commercially available pheromones. A resolution of participants at the guava moth meeting in Kerikeri was that grant applications would be made to AgriMARDT and/or FRST for funds to undertake a delimiting survey of the extent and frequency of the pest in the Kerikeri (and perhaps a less rigorous survey for the rest of Northland). The research proposal to be written by HortResearch on a contingency basis (i.e. if successful, HortResearch would be the supplier). Initial funding probably via the Fruit Growers' Federation (chairman, Rick Curtis) as none of the other grower representatives have significant funds (such as those obtained by levees on their members). Funding via the Sustainability Fund is unlikely at present as this body is mainly concerned with management rather than research. Later research on this pest should lead to identification of possible avenues of control, including pheromone-induced disruption of mating of the moth, or lure and kill methods.
In the meantime, removal of infected fruit and cleaning up areas under trees is recommended. Removal of a susceptible crop could help in disrupting the movement of the moth from one fruit crop to the next. For example, there was a major infestation of loquats by the guava moth during October/November, just as the macadamia crop was setting. The group learned that introducing pigs to eat the remains after macadamia harvesting has had a big impact on reducing levels of infestation in a subsequent year.

The current focus on the use of pheromones for delimiting surveys, rather than immediate research on use this agent for control is unsatisfactory. Other possible methods of control, such as the parasites and predators that probably keep this moth under control in Australia also need to be investigated. Urgent research on the life cycle of the moth, the sequence of plant hosts attacked by the caterpillar, identification of new fruitcrops/other plants attacked by the moth, and the method by which the pest spreads to new areas also requires work. The guava moth is unlikely to stay in Northland, although the severity of infestations may be lower in colder areas. The director of the Kerikeri HortResearch station informed us that the moth has now reached Auckland. The warmer fruit growing areas of NZ, such as Bay of Plenty, Hawkes Bay and Nelson may be at particular risk.

Gordon Lees

Guava fruit moth found on northern macadamias - by Glenys Christian

An Australian pest which the Ministry of Agriculture and Forestry assessed just two years ago as not being likely to be a commercial risk in this country has been found on macadamias in the north.

The Australian guava fruit moth, Coscinoptycha improbana was found on a mandarin orchard in Kaitaia in 1999 where it was believed to have blown to from across the Tasman. It was later discovered in Ahipara and Kerikeri and an entomologist carried out a delimiting survey. It was decided, based on the results, that the moth was too widespread to eliminate.

MAF spokesperson, Gita Parsot said that as the moth is considered a backyard pest in Australia and was not a problem on commercial orchards it was thought it was likely to be the same in this country. But now the pest has infested several Northland macadamia orchards with one having 80 percent of its production destroyed by the moths larvae which burrows into the nuts.

Tree Crops Association North Island vice president, Diana Loader brought some of the nuts south to Auckland to be examined on her recent tour and confirmation was made that the pest is indeed the guava fruit moth.

Organic risk.

Macadamia consultant Ian Gordon says the discovery is a serious one for the fledgling industry- which makes sales worth around $1 million annually. Many growers, including the one whose property the pest was discovered on, aim to run an organic production system but the only way of controlling the moth is by chemical sprays which may have to be used every two to three weeks.

He is also concerned that the pest may be spread rapidly to other areas because many of the macadamia nuts grown in Northland are sent to south and west Auckland to be processed.

While the industry had excellent prospects to grow, it could be "absolutely flattened by something like this," he said.

HortResearch scientist Karyn Froud, who identified the pest in macadamia nuts from trees on the orchard said as eradication was not feasible the problem now passed over to the industry to find funding to control the pest.

Pheromone traps

Another Christchurch based HortResearch scientist, Max Suckling is working on a pheromone mixture to attract the moth as a first step to trapping it and discovering exactly how far it has spread. Field tests of the mix are being carried out at present but he said it was already thought likely the pest had moved further afield on plant material.

The moth is also known to be found on feijoas, citrus fruit, plums, peaches and nashi. lt is found as far south as Tasmania in Australia making it a potential pest risk in most of New Zealand's fruit growing areas.

National Member of Parliament David Carter, raised concerns about the pest last year when he was the party's biosecurity spokesman. He said the spread to macadamias showed once again that rapid Government action was necessary as soon as new pests were discovered. "We missed a golden window of opportunity," he said. "The Government has to be prepared to act immediately and put the resources in to attempt eradication."

BIOSECURITY CONCERNS FOR TREECROPPERS

Between 20 to 30 new plant pests now reach NZ each year. Pests that have generated considerable concern include two insects that attack a range of trees and have been detected in NZ only over the last two years. One, the painted apple moth, has received a lot of media attention and government funds for its eradication. At the last count $10 million has been allocated for the eradication of the painted apple moth and this figure is likely to increase, $20 million has been mentioned. The other, the guava moth, Coscinoptycha improbana, has received only a cursory investigation by MAF Biosecurity and no funds have been set aside for further investigations, let alone funds for controlling this pest.

These contrasting responses by MAF Biosecurity require investigation as to the reasons behind their decisions, the role of publicity in the media and parliament in the release of government funds for control or eradication, and also of whether the responses of MAF Biosecurity in either case were adequate. The guava moth meeting at the Kerikeri HortResearch station provided an insight as to the decision-making processes of MAF Biosecurity.

The initial response of MAF Biosecurity is firstly to identify the new pest. In the case of a serious threat from a known pest, e.g. the Mediterranean fruit fly, the entire response is automated as the seriousness is known, surveillance and eradication procedures have been determined in advance and are known to be effective, and all necessary materials are available. Otherwise, once the pest identity is known, and it is determined that it is unwanted (some new organisms such as some insect parasites may be advantageous), information is collected from experts at home and abroad as to the seriousness of the threat. Following that, and information on the spread of the pest within NZ, a decision is made as to whether MAF Biosecurity will take no further action after advising key individuals and organizations, or whether it will take further surveys on the spread of the pest and the environmental damage done, and undertake eradication procedures.

So why did MAF Biosecurity respond differently with respect to the painted apple and guava moths? With the painted apple moth, the threat was determined to be of major economic significance, the incursion by the pest confined to a local area and eradication likely and justified on a cost benefit analysis. On the other hand, with the guava moth, information from Australia and elsewhere was that the pest was minor, (of backyard treecrop significance only!) and that the spread of the pest through Northland was such that eradication was unlikely. No further action was therefore taken, apart from the minimum notification required by legislation. It should also be remembered that the guava moth is one of 20-30 new plant pests reaching NZ each year and that others are regarded as more serious.

However, there are a number of defects in the response of MAF Biosecurity that need to be addressed.
1. The time taken for a response. MAF Biosecurity advises that a decision on the risk arising from a new pest and whether MAF Biosecurity is going to be involved further should be within 12 days. This was obviously not followed in the case of the guava moth.
2. If the decision is for eradication, the time taken to institute the procedure. For the painted apple moth, delays have caused a huge increase in the cost of eradication, due to spread of the moth from the initial site of infestation.
3. Notification of interested parties if a decision is made against eradication. This has been woefully inadequate for the guava moth. Lack of information and prevarication by MAF has meant that growers have not had time to plan for their own responses, knowing that MAF Biosecurity was not going to do anything more.
4. A lack of communication between the CRIs. For example, HortResearch in Kerikeri didn't even know of the problems caused by the guava moth (and the infestation of their own macadamias) in spite of HortResearch in Lincoln developing a pheromone for this moth.
5. The cost-benefit analysis. What criteria are used to determine benefit? Costs involve compensation to growers for the loss of any crops destroyed.

Some more general concerns also arise. Notification of insect pests can involve members of the public sending in specimens, especially after media coverage. This has the potential to overwhelm diagnostic entomologists in the laboratories of MAF Biosecurity, especially if most specimens are of already known species. Laboratory staff at MAF Biosecurity were downsized 30% during recent restructuring, exacerbating this problem. Preliminary screening of specimens submitted by the public would seem to be essential, perhaps carried out by council staff, school science teachers, or suitably qualified/trained members of the NZTCA. It seems farcical that such procedures do not yet exist.

The lack of response even if a pest is deemed not to be of economic significance to NZ. The devastation wrought by the guava moth on some organic orchards in Northland (up to 90% destruction of some crops) and its attack on new crops (e.g. the macadamia) illustrates that new insect pests in NZ can have totally different and serious consequences than those found in the home country of the pest. This can be partially due to a lack of predators/parasites of the pest that are found in its native country. An immediate eradication programme would reduce the risk of unexpected damage and be cost effective in the long run.

MAF Biosecurity are evidently undertaking their own analyses of policies and evaluations. Treecroppers should consider whether they wish to make submissions.

Gordon Lees

Newsletter Update

In the last newsletter, pests attacking bananas and apples were mentioned as possibly due to the guava moth (fruit driller caterpillar). The caterpillar in the banana was identified as a leafroller. A possible outbreak in April, 2002 of the fruit driller caterpillar in feijoas on a property at Waitoki, near Auckland, was found to be a brown-headed leafroller, even though it had entered fruit. Evidently, leafrollers can occasionally enter fruit.

Previous reports of outbreaks in macadamias in Auckland have also proved false, an outbreak in Pakuranga in November 2001 was identified as the Indian meal moth, and that in Patetonga, in late 2001 also proved false. The moth at Patetonga is eating macadamias is storage containers. The problem in Gary Colebrook's apples, and incidentally found this year elsewhere in Northland, appears to be a severe infestation with the apple green crinkly virus, which is endemic in Auckland.

Gordon Lees

Unwelcome newcomer gets the pheromone treatment - HortResearch

More about the Guava Moth Fruit Driller

http://www.treecrops.org.nz/news/news02q2/guavadrill.html
Launched: 28/May/2002 - Modified: 2008 July 11