New Zealand Treecrops Association

Research - Guava Moth

Action on the Fruit Driller Caterpillar (guava moth)

Contents

"This was an unsatisfactory situation for the Northern Branch..."

After the second guava moth meeting in Kerikeri last April, 2002, it became clear that any action on methods to control the pest would be a long time coming. This was an unsatisfactory situation for the Northern Branch, and we approached John Clearwater for help. John is one of NZ's foremost experts on the biological control of insect pests and the successful campaign to rid Auckland of the white tussock moth was largely the doing of his group. John was prepared to help with only the barest contribution to his costs being supplied by the Branch (now supplemented by a grant of $750 from NZTCA National Management Committee).

Members in Kerikeri grew up pupae for pheromone identification and these were shipped to Canada mid-July. Within 6 weeks the group in Canada had identified the pheromones and trials in Northland indicate a very successful product - 10 to 20 times better than that developed by HortResearch over a much longer period.

Due to John's generosity, the Northern Region Branch has a partnership arrangement with John's group and is a joint signatory on a Provisional Patent (NZP 521850) awarded to the partnership. Thanks are also due to Patent Attorney, Donald Ensor, who has been most generous with his assistance. Thanks also to the volunteers who have provided practical help for the campaign as well as contacts. Surveillance traps based on this pheromone product should be available shortly.

However, until a control method is introduced we are not much better off and this will continue to be the focus of our future actions. We need up to $25,000 to defray the expenses of developing pheromone-based control products and ways of finding this capital are now being explored.

The Guava moth Coscinoptycha improbana in New Zealand

John Clearwater - Clearwater Research and Consulting - 23 Nov 2002

Abstract
The identification of a multi-component sexual pheromone of Coscinoptycha improbana has been field tested in Kerikeri. This pheromone blend shows some evidence of greater attractiveness than competitors products. This pheromone is a key tool for control and possible eradication of the pest.

The challenge
The arrival of the moth in Northland presents a number of serious challenges. Most of the growers affected are small, few are significant exporters and the fruit species attacked are mostly second tier species that contribute less to the horticultural exports of our country. Northland is not the biggest horticultural area of New Zealand. We could well imagine the fuss that would result if the moth had arrived in Te Puke and infested Kiwifruit or Hastings on apples. The Northland growers have effectively been abandoned to their fate where Te Puke kiwifruit growers would now be receiving the full assistance of the MAF. Observers of the dismal MAF program to eradicate the painted apple moth (PAM) from Auckland may well think that might be unlikely to achieve very much however.

Our first need is identify the possible consequences of the invasion. Transferring the infestation to a country that receives our exports of fresh fruit would be very costly to our reputation and the engendered suspicion would mean long delays and quality -sapping disinfestation treatments of all of our fresh exports. The insect is extremely cryptic in its early stages of infestation. The early caterpillar makes a tiny pinprick hole as it burrows into the fruit. Once inside the excavations are not visible until the fully grown caterpillar chews its way out. The exit hole is much larger and easily seen. Experienced orchardists closely inspecting boxes of fruit in the first stages of infestation would miss most if not all of the infested fruit.

Two fruit species, Satsuma Mandarins and Feijoas, are infested by this pest species are export crops. Mandarins from the infested Northland region are currently being exported to Japan while feijoa exports to California were stopped.

The first need is for a determination of the area of infestation so that all growers an agreed distance from the infestation can continue their usual business. Growers inside the infestation should not send fresh fruit outside the area. Several growers in the area to their great credit have already decided not to risk spreading the infestation. They should not be allowed to bear the financial costs alone........this is a clear case for the wider community through the government to share the cost by contributing financial support.

This monitoring should be carried out continuously so that an accurate and updated map is always available to growers. Failure of accurate mapping of the infestation is a major reason why the PAM program has been such a shambles. Insects keep popping up in areas outside the area receiving sprays, most recently in Newmarket. Intensive monitoring of the earlier infestation of White-Spotted Tussock Moth (WSTM) was a key contribution to the rapid, cost-effective elimination of WSTM........the insect was never allowed to move beyond its very clearly defined initial beach-head. The key tool in the WSTM program was the sex pheromone, first as a natural source in the form of un-mated females then as a synthetic copy placed in sticky traps. These traps allowed a clear measure of the dwindling WSTM population as it was assaulted with well-directed sprays. Part of the failure of the PAM program is due to the failure to identify the pheromone of the PAM.

The pheromone of Coscinoptycha improbana would also be a key tool for control and possible eradication of this pest. Dr. D. M. Suckling of Hort research has claimed to have identified the pheromone and small numbers of sticky traps can indeed be observed to be catching C. improbana males in a Kerikeri orchard. Dr. Gordon Lees of the Tree Crops Association asked Dr. Suckling for the identity of the pheromone components but was refused despite this information being obtained through public good funding. Dr. Lees turned to our team and asked for assistance. I am the NZ member of the team responsible for the bio-assay of pheromone blends. Prof. Gerhard Gries is the head of a group of research biochemists and synthetic chemists working in Simon Fraser University, Burnaby, Canada (including Regine Gries, Grigori and Eugene Khaskin). Our last collaboration was on the identification of the WSTM pheromone.

Live insects were collected and reared by Eileen Welch and Mary Knowles of Kerikeri and sent under permit to Canada. The female moth has a pheromone gland near the ovipositor. This gland was snipped from the abdominal tips of females 1-2 days old, and placed in hexane solvent. Samples of female extract were injected into the column of a Gas Chromatograph. Biologically active regions of the effluent moving off the column will be detected by the electrical response of an isolated male C. improbana antennae held in the air-stream. The chemicals present in the active regions were identified by mass spectrometry and synthesised. Blends of antennae-active chemicals were made up in the proportions seen in the extracts, loaded on to rubber sleeves and couriered to New Zealand for bio-assays in Kerikeri orchards.

The first trial showed that few males could be caught by any one component by itself. Component A caught 17 males(white), B a single individual(yellow) and C none at all(red),(see fig.1). Mixed together (green or black), the result was variable, one mix much more attractive than the other. The black lure was compared with the Hort research lure purchased from Fruit Fed Kerikeri and found to be 10 times more attractive. The purple lure was the blank trap.

Fig1 - First field trial of pheromone blends (see text for colour codes).

The second set of lures looked at the response to a single component, the best three component blend and three two component blends. We discovered here that the results differed between Kerikeri and Waipapa to the North (see figs 2 and 3).

The BC lure catches good numbers of Heterocrossa rubiphaga, the raspberry bud moth (fig 2&3). This is a New Zealand endemic(found nowhere else) and is a serious pest of berry fruit in New Zealand. This lure catches no C. improbana in Waipapa (fig 2) but does catch this species in Kerikeri. (fig.3). The best lure for C. improbana is AC in Waipapa and ABC in Kerikeri. Very small numbers of both are captured with the AB lure in Waipapa.

Fig 2 - trial of the second set of blends at Waipapa

Fig 3 - Trial of the second set of blends at Kerikeri.

This data is protected by patent 521850 filed on October 8th 2002 and owned jointly by the Northern Region Branch of the Tree Crops Association and the science research group.

Now that a potent pheromone blend is available, work on monitoring the pest should begin. All growers in Northland should use both the ABC and the AC blend until we have a clear idea of the distribution of the two types and indeed if the two types continue to be apparent. The first set of lures will be on sale as this issue goes to press and application should be made to Dr. Gordon Lees.

Control measures based on pheromone activity.
A burrowing pest always presents difficulties for control with applications of pesticide spray. Caterpillars exposed on the plant surface might be expected to be an easier target.

The pheromone may be used as a control technique in two ways. Slow release dispensers of the pheromone of the codling moth confuse the males of this species. The females pheromone signal is lost in the clouds emerging from the dispensers and remain unmated. An account of the successful use of this technique by myself, Tony and Thea Belcher to produce the first export crop of organic apples from New Zealand is found in “Soil and Health” June/July1995 p.8-9.

A second method was developed by Dr. Pierre Charmillot in France. Globules of tar-like materials are placed, one or two per tree to form traps for the males. The blob contains a low dose of insecticide (most likely a synthetic pyrethroid) and the specific pheromone. Prowling males locate the blob, identify it as a female and attempt to mate. This eager effort picks up enough insecticide to kill the male. A population stripped of its males collapses as females are unable to lay fertile eggs. This is known as an “Attract and Kill” strategy.

I have the equipment needed (primarily a field cage) and Prof. Gries agreement to produce the prototype pheromone dispensers and the Attract and Kill material. Cage trials could take place this spring with field trials in grower orchards of materials found to be successful the following year.

Funding of the research project.
All New Zealand scientists are familiar with the difficulty of obtaining funding. Detailed applications that take a great deal of time and effort are submitted to the various funding bodies and after lengthy consideration are mostly rejected. Whole seasons can be lost in this fruitless pursuit of funds. The cage trials would take 3 months and cost $25,000 +GST. A contribution of $1000 from the TCA account provided some of the costs of the initial project to identify the pheromone, but we are unable to continue to work with this level of funding. We need to debate how we can continue with this project. The answers may be in part political, we may be able to secure funding from the appropriate funds set up for this sort of project. Recent accounts from AgMardt that show a negative balance of about $1 million are not encouraging.

Campaign to halt guava moth spread - By Aimee Cox, Hibiscus Coast Reporter

A Helensville man is behind a national campaign to stop an invasive moth from spreading south and potentially ruining fruit and nut industries in Rodney and other parts of the country. Dr Gordon Lees, the spokesman for the northern branch of the New Zealand Tree Crops Association (NZTCA), says the group is working on a solution to control the guava moth from spreading further south from Kerikeri, but needs money to make it work. ”We are on the threshold of developing methods that could limit the spread of this pest that threatens New Zealand fruit and nut industries,” he says. Although he says the moth, which has killed commercial fruit and nut plants, including mandarin, macadamia nut, feijoa and peach in Northland, is currently confined to that area, it is likely to move down to Auckland. Hort Research have predicted that Bay of Plenty and Hawke's Bay have an 85 per cent probability of suffering similar problems as Northland is facing, he adds.

New Zealand Forest and Bird also believe that the moth is spreading further south since it was first confirmed in Ahipara, near Kaitaia, in 1997, and that Rodney, may be the next target. However, the Ministry of Agriculture a Forestry says, although it has heard rumours it has spread further south from Kerikeri, it has no confirmed cases. Spokesman Phillipa White says when MAF first found the moth they researched it and decided it was a minor pest, so eradication was not necessary at the time. When MAF decides that something is of minor concern the pest’s management goes back on the regional body, at this stage the Northern Regional Council. It is also up to farmers to watch out, she says and advises them of a pheromone that is for sale from Hort Research.

Forest and Bird asked MAF to investigate whether the moth may affect native trees, but Ms White says the research has already been done and from that it was decided this was not a concern.

Barney Stephenson of MAF's biosecurity unit says he is "not surprised" it may be elsewhere, but says the trend in Australia is that it thrives in the mainly warmer climate, so it may not like Auckland.

When the pest was first found, MAF had to make a "tough call" not to eradicate it, but it has to consider resources and priorities, he adds. Dr Lees says New Zealand entomologist Dr John Clearwater has been consulting and monitoring traps have been developed. But more needs to be done, including mating disruption and attract and kill stations. “Because the need is urgent and funding from Government granting bodies uncertain and subject to long delays, the northern region of the New Zealand Tree Crops Association is embarking on a national appeal to develop methods to control populations of the pest, he says.

They estimate it will cost about $25,000 plus GST to develop the two methods.

FRUIT DRILLER CATERPILLAR UPDATE

We are now over the minimum to start the research on pheromone methods to control guava moth populations and Dr Clearwater is already making plans! But we are not there yet and we need more help from members, especially those in Northland. We need more funds, and also need members prepared to grow up pupae of the fruit driller caterpillar for John's research. Firstly, while we are half way to target (see below for why), we need to raise the full amount because no commercial grower organization or regional council or fruit grower charitable trust approached is prepared to help (at least 24 organizations contacted). If you can't personally contribute, talk to your neighbour or your local orchardist to convince them of why the research is important and should be supported. If we don't support it, the research won't be done for years.

There has been a lot of concern following its appearance in a feijoa crop in Whangarei, much further south than previously and it has apparently skipped a lot of area in between. MAF has tried to downplay it (again) saying it is just a rumour (as reported in April 30th Rodney Times). However, it was identified in Whangarei feijoas by Jenny Dymock, an entomologist involved in the guava moth scare since its beginning (although she would like its presence in Whangarei to be confirmed). What would have happened if this feijoa crop had been exported??

Organic growers remain particularly at risk. One trial of spraying Cold Water Surf^TM has seen infestation markedly reduced while unsprayed feijoas were badly infested with the caterpillar. Systemic insecticides will probably work for conventional growers, providing this is acceptable for export markets. Is this what the commercial growers are relying on?
One grower has reported that Orthene has reduced infestation to negligible proportions in feijoas - however care will be needed to ensure that resistance does not develop.

Philanthropists - anyone who cares -
Contribute to our urgently-needed Research Funds -
Our Bank: Westpac
Bank Account No: 03-0463-0143358-00
Account name: New Zealand Tree Crops Association Inc.
Project Reference: Guava Moth
Receipt (for NZ tax rebates etc.)? Send us your details -

http://www.treecrops.org.nz/resrch/guavamoth/guavact.html
Created: Saturday, 19 July 2003 - Modified: 2009 November 08