Australasian Association of Nematologists

Regional News

News from the ANIC Nematode collection

As usual, I open the account of news from Canberra with a report on the collection which is the basis of many of our activities here at CSIRO Entomology.

GRDC continues to support the collection, and since the last report, we have received a diverse range of nematodes: some Pratylenchus, including some of the apparently undescribed species, some Helicotylenchus, some Meloidogyne, and some mermithids. For those of you who have never come across these nematodes, they are large for soil nematodes (up to about 1 cm), with most juvenile stages internal parasites of insects, and adults free-living in the soil but not feeding. The stage most commonly encountered is the infective juvenile, which, after hatching, is seeking insect hosts. Under the right conditions they can be very numerous.

For a genus which is such a major pest of wheat and many other major crops, I am continually amazed at the variety of characters of Pratylenchus in the specimens coming into the collection. It now seems quite likely that there are species or races or pathotypes which we have not previously identified, and that we still have quite a lot to learn about the systematics of the genus Pratylenchus. This brings me back to the collection, and the plea to keep sending us material. It is only through building a large collection, encompassing as much geographic, host crop and seasonal variation as possible, that we can recognize previously undiagnosed problems. It is only through collections that new threats will be identified. So please, when you are finished with your nematodes, send us some specimens. They will be looked after and really will be of great use in the future.

If you want to donate material, in whatever form (fixed or unfixed, mounted on slides or not, in pure or mixed culture), please contact me at:

CSIRO Entomology
GPO Box 1700, CANBERRA ACT 2600
phone (02) 6246 4371, fax (02) 6246 4000
e-mail: mike.hodda@ento.csiro.au

Other research on nematodes continues with John Curran, Robin Bedding and myself all beavering away in our particular fields. John, with Felice Driver, is studying genetic relationships of plant parasitic nematodes, with continuing development of molecular diagnostics for nematodes as a priority. SARDI and VIDA are collaborating with John in testing various molecular methods. Robin continues work on identification and mass production of nematodes for insect control. I am studying nematode pests of clover, and supervising a PhD student from Orange Agricultural Institute (University of Sydney). I am also completing my electronic key to freshwater aquatic nematodes, sponsored by ABRS. This key will be completed shortly. Anyone who would like to try a preliminary version of this key should contact me. All feedback will be very welcome. My next major systematic project will be dorylaimids, which of course includes dagger nematodes (Xiphinema spp.) and Longidorids (Longidorus and Paralongidorus).

Mike Hodda

Australian National Insect Collection, CSIRO Entomology

NEWS FROM QUEENSLAND

I was given the opportunity recently to travel to Cameroon to participate in a meeting of the Nematology Working Group of PROMUSA. PROMUSA was developed jointly by the International Network for Improvement of Banana and Plantain (INIBAP) and the World Bank to bring together, at a global level, all the major efforts in the area of banana and plantain improvement. Briefly, the aim of the program is to develop banana and plantain cultivars which are resistant to the four most important biological constraints, viz. nematodes, viruses, Fusarium and sigatoka.

Working Groups were set up for each of these pathogens to develop collaborative projects which would hopefully eventually be funded as global projects. The Nematology Working Group was given the task of first determining its composition which is in the following table. These researchers must be working specifically on the priority research needs identified by the group, and be willing and able to participate in collaborative projects and in developing new proposals.

The Working Groups were then asked to develop potential projects which would lead to the eventual goal of resistant cultivars. Because of the wide range of nematodes, banana cultivars and climates worldwide, the Nematology group decided on a consortium approach where a large problem would be tackle by many small projects throughout the world. The first of these consortia aims to screen a large number of genotypes for resistance using similar methods so that results can be compared between regions.

Such consortia may also be used in future to study intra-species nematode biodiversity and yield loss assessments.

This type of approach to tackling major global nematode problems may be applicable to other crops. It may save duplication of effort and these larger projects are often more attractive to certain donors.

Julie Stanton, QDPI/QHI Indooroopilly.

Museum specimen collection

As a museum curator it is my job to ensure specimens in my charge are cared for in the best possible way to ensure their long term viability. There are two practices commonly used with free-living or parasitic nematodes (other than those found parasitic in vertebrates) which differ from those more usually adopted for invertebrates in museum collections.

The first I mentioned in a previous note, viz. normally invertebrates in museum collections are preserved in alcohol, but in specimens of plant/soil/free-living nematodes we see gradual deterioration when stored in alcohol - even after fixation in formalin. In these specimens lipids leach into the preserving fluid and structural integrity is slowly lost leaving the specimens flaccid. Long term storage in 3% formaldehyde prevents, or at least minimises this.

The second is the use of Cobb mounts, with specimens stored in glycerine, usually ringed with paraffin wax, and sealed. In most other invertebrates, the specimens are mounted in Canada balsam. Balsam has the clear advantage of longevity - insects in amber from the Cretaceous period (80 million years bp) are still recognisable! Glycerine mounts conversely require continual monitoring and restoration. Although some specimens remain excellent in glycerine, some do degrade and become extremely transparent - they may even virtually disappear.

I need to balance my responsibilities. The cost of continual monitoring and repeated restoration, with the concomitant risks of loss from being too late or too clumsy, must be weighed up against the additional effort needed to mount in balsam, along with any advantages that the glycerine method may have. Clearly the specimens need to be of use and just as clearly most nematologists favour the glycerine method. Why?

I have just returned from a 2 month trip to the Americas which included visits to the nematode collections at University of California, Riverside, UC, Davis, the US Department of Agriculture collections at Beltsville as well as the marine and free living nematode collections of the Smithsonian Institution, Washington.

Everywhere I asked about the advisability of the glycerine versus the balsam method for slides of nematodes. Everywhere the answer was the same. There are some minor? advantages to glycerine (quick, easy to reverse) and Cobb mounts (light, flippable), but agreed disadvantages from risks of drying and transparency. Balsam was used by the early workers and no cogent reasons for not using it were advanced. True, it is not so quick nor is it so easily reversible, and slides are not flippable for high magnifications. Recent convention seemed the main reason for glycerine - and the fact that the slides are made for the immediate and convenient use by the researcher less concerned with long term preservation.

One sobering event occurred. I was to visit the collections at Purdue University (Indiana) which, according to the survey of parasite collections done by the American Society of Parasitologists in 1982, was the largest in the USA (nearly 200,000 specimen lots including many entomophilic nematodes). I was advised not to come as lack of finances over the years had led to an inability to keep up the monitoring and restoration, i.e. proper curation had not been possible and the collection was now virtually unusable. Perhaps this was hypersensitivity, but it highlights the vulnerability of collections to neglect. If things can go wrong they will, and any means to stave off problems must be seriously considered.

At present we are doing our best to keep up with the nematode collections at the QM, and the Queensland Department of Primary Industries is generously assisting so that we may monitor and restore regularly. Is it wise or cost effective to continue this way? I believe, as restoration is required (beginning in the second half of 1999), I should gradually transfer specimens to balsam unless I receive cogent objections. I assume this option is not now too late. In future, should I insist all taxonomic collections (as opposed to working collections) be mounted in balsam prior to accession by the museums? I would much appreciate comment. I want to know what is best, but I need to have solid argument (data) to continue along the present course.

Help me.

Dr Lester R.G.Cannon
Senior Curator, Worms, Queensland Museum
PO Box 3300, South Brisbane, Qld. 410, Australia
Ph +617 3840 7724
FAX +617 3846 1226
Email: L.Cannon@uq.net.au OR LesterC@qm.qld.gov.au

NEWS FROM SOUTH AUSTRALIA

Frances Reay retired from nematology at the end of 1998. She is planning to pursue a very different, much more contemplative life. Frances recently completed a revision of some Australian species of Ogma, and is finalising her work with Prof Hal Heatwole (North Carolina) on Antarctic nematodes.

At the University of Adelaide, a position for Lecturer in Plant and Soil Nematology (Department of Crop Protection) was advertised, and a very strong field of candidates applied. The position is for five years in the first instance, and is jointly funded by GRDC and the University. It was offered to Dr. Ian Riley, and we look forward to welcoming him to Adelaide in January, 1999.

Ian's arrival will allow Kerrie Davies to retire and concentrate on work on Fergusobia.

Valerie Kempster continues work on her Ph.D. project. She has been able to show that induced systemic resistance (IRS) does occur in white clover, and that its induction leads to significant reductions in fecundity of Heterodera trifolii. She was successful in obtaining a travel grant from RIRDC, and presented her findings at the joint APS/ESA Conference in Las Vegas, U.S.A., in November, 1998.

Mark Potter (jointly supervised by Kerrie Davies, Tony Rathjen and Vivien Vanstone) has been awarded his Ph.D. In his project, he examined the potential of Brassica tissues for suppression of Pratylenchus neglectus. He also looked at the potential for selection to breed new strains of canola with elevated levels of glucosinolates, which break down to the isothiocynates responsible for suppression. His thesis is summarised elsewhere in this issue.

Andreas Hensel, Terry Bertozzi and Sharyn Taylor are all approaching the end of their Ph.D. projects. Andreas has been examining the interactions between Rhabditis necromena, bacteria and the black Portuguese millipede. Terry has been working on the biology, taxonomy and management of the flood plains staggers, which involves Anguina, bacteria, grasses and stock. He is now writing up 'the hard way', having moved from the nematode project to one (with Prof. Margaret Sedgely in the Department of Horticulture, Viticulture and Oenology) on viruses of almonds. Sharyn is also writing up her work with P. neglectus.

Thanks to a travel grant from GRDC and RIRDC, Suzanne Charwat attended the European Society of Nematologists Meeting in Dundee in August, where she presented a paper. While in Europe, she visited David Glen at Long Ashton Research Station, Bristol and Bernhard Speiser at the Institute for Organic Agriculture in Frick, Switzerland. Both David and Bernhard are part of an EC project for novel methods of slug control and involved in the research and development of Phasmarhabditis hermaphrodita, a commercially available nematode for biocontrol of slugs. In Europe, Suzanne learnt that nematodes for biocontrol are sold at prices which make them economic non-starters for broad-acre cropping.

Suzanne came back to Australia to complete her final field trials to assess the potential of a locally isolated rhabditid (XM13) as a biocontrol agent of helicid snails. XM13 kills adult helicid snails in soil-based laboratory bioassays. Her 1998 trials examined both adult mortality and the possible reduction of snail fecundity during breeding and oviposition in soil containing XM13. In the lab, Suzanne showed that snails on soil with low numbers of the nematode had greatly reduced fecundity (number of egg clusters/snail and number of eggs/cluster) and that newly hatched snails were very susceptible to the nematode. In the field, XM13 does not kill significant numbers of adult helicids. Unfortunately, there were much lower than expected numbers of newly hatched snails in all treatments (controls as well as plots to which XM13 was added), probably due to the natural presence of a rhabditid nematode in the field which was found attacking and killing the very young snails. This is a nematode which we had not previously seen. Thus, it seems that while inundative applications of nematodes for control of snails is likely to be too expensive for broad-acre cropping, farming methods which encourage populations of bacterial-feeding nematodes may help to reduce the numbers of young snails developing in the field.

Kerrie Davies, University of Adelaide.

NEWS FROM NEW SOUTH WALES

The Sydney based nematologists have had a great 6 months for meetings, conferences and symposia. In July, I drove over to Macquarie University to hear Alamgir Khan's talk at his department's seminar meeting. An impressive selection of biochemistry was presented and it looks like his work on the biocontrol of CCN and Meloidogyne by Paecilomyces lilacinus is coming along very well. Rita Holland, Alamgir and I had a very pleasant lunch, over which Alamgir and I discussed our travel plans for the International Symposium of Nematologists in Dundee, Scotland in August.

We arrived in Scotland to the sound of bagpipes, and the bagpipes did not appear to stop for the next two weeks. Dundee was a terrific location for the symposia (close to distilleries, castles, the countryside where they grow the barley for the whisky and of course the terrific lecture facilities at the University of Dundee). The organisation committee worked non-stop to ensure our every question was answered and that we could pronounce "worms" properly with a thick Scottish brogue. The symposia were very friendly meetings and well balanced (almost equal time allowed for presentations and socialising). A highlight of the meetings was hearing the work of Valerie Williamson et al. on characterising and cloning the Mi gene for resistance in tomato. The poster sessions and talks were varied and the meeting was a terrific opportunity to see the enormous impact of nematode damage to agriculture worldwide.

After Dundee, I travelled back to Edinburgh for the largest meeting of my life - the International Congress of Plant Pathology. The congress had it all, brand new venue, royalty, security guards with a mission to protect the rest of society from the potential evils of plant pathologists, bagpipers (more!) and the most comprehensive, up-to-date array of topics in plant pathology. The highlight of the Congress, for me, was the terrific symposia on systemic induced resistance in which the latest and most exciting research was presented. The poster sessions were so large they were held in several venues (including a sauna cleverly disguised as a marquee with eerie sloping floors) and there were strict timetables for poster check-in and departures. I met the leaders in systemic induced resistance research at my poster and had terrific discussions on all aspects of my work. Thanks must go to the International Society of Plant Pathology for helping with funding for travel and registration. Scotland was a wonderful interruption to my thesis, which is now in its final stages and should be finished soon.

Kirsty Owen, Department of Crop Sciences, University of Sydney.

NEWS FROM NEW ZEALAND

Gregor Yeates has been made a Fellow of the Royal Society of New Zealand - a rare honour for a nematologist!

The following is a report from Prof. John Barrett from the Institute of Biological Sciences, University of Wales, Aberystwyth. It describes the work we did during the 3 months or so he spent with me on study leave. I am now continuing this work in collaboration with our Biochemistry Department.

After nearly three months in Dunedin, it is now time to return to a second winter and the start of term in Wales. During the visit, David and I have been trying to characterise the thermal hysteresis protein (antifreeze protein) from an antarctic nematode Panagrolaimus davidi. This nematode has the unique ability to survive intracellular freezing and previous work by David had shown that they did indeed contain an antifreeze protein. After perfecting the 'splat freezing assay' and some abortive attempts at making affinity columns out of ice, we have been able to show that the nematode protein has an activity comparable to that of insect antifreeze proteins. It has a molecular weight of approximately 30kDa; it is not a glycoprotein and is active over a wide pH range. The best characterised antifreeze proteins are of course those from antarctic fish, which show a thermal hysteresis of 1 to 1.5°C. At least five different classes of antifreeze proteins occur in fish and they are all totally unrelated. This raises interesting questions about the evolution of these proteins.

One of the fish antifreeze proteins for example seems to be derived from part of the trypsinogen gene, another is related to a vertebrate lectin. So far only three invertebrate antifreeze proteins have been characterised in any detail, two from beetles and one from a moth larva. Again they fall into two totally unrelated groups, but the main interest lies in the fact that these invertebrate proteins are able to induce a much larger thermal hysteresis (up to 5°C) than the fish antifreeze proteins. The relatively small amounts of material available from P. davidi makes purification of the antifreeze protein difficult, however, a start has been made and before too long we hope to have enough protein for sequencing.

I'm hoping to visit Australia in March 2000 and will be based at La Trobe University, Melbourne working with Alan Marshall. We will be applying various electron microscope (and other) techniques to the mechanisms of anhydrobiosis in nematodes. I'd like to hear from anyone who'd like to talk to me while I'm in Australia.

David Wharton
Department of Zoology
University of Otago
P.O. Box 56
Dunedin, New Zealand
Tel (064) (03) 479 7963
Fax (064) (03) 479 7584

Dr Usha K Mehta, Nematologist & Head, Division of Crop Protection, Sugarcane Breeding Institute, was awarded " Outstanding Woman Agricultural Scientist Award" of Indian Council of Agricultural Research (ICAR) in recognition of her contributions to sugarcane nematology.

Dr N. Somasekhar, Scientist (Nematology), Sugarcane Breeding Institute, was awarded "Prof. D. J. Raski Young Scientist Award" of Nematological Society of India (NSI) for his research paper on "Biorational Approaches to Nematode Management for Sustainable Sugarcane Production". This was presented at the 9^th meeting of the NSI held at Gujarat Agricultural University, Anand, India.

Dr N. Somasekhar, Scientist (Nematology), Sugarcane Breeding Institute, was awarded "Smt. Snehlatha Banerjee Gold Medal" of Academy of Environmental Biology, India, for his paper entitled" Soil Biodiversity: Role in Ecosystem Processes, Sustainable Crop Production and Economic Development", published in Proceedings of Academy of Environmental Biology, Vol. 7 (1998).

Dr. N. Somasekhar, Sugarcane Breeding Institute, Coimbatore - 641 007, India