M. Hodda

Root-Knot Nematode (Meloidogyne incognita) on Bitter Melon (Momordica charantia) near Darwin, Australia

The Root-Knot nematode Meloidogyne incognita was identified morphologically from diseased Bitter Melon root samples taken from a farm at Buckley Road, Humpty Doo, Darwin. Meloidogyne species have been recorded from the Northern Territory on various hosts including bitter melon, but none were identified to species, so this is the first report confirming Meloidogyne incognita on Bitter Melon from the Northern Territory, Australia.

Pratylenchus quasitereoides n. sp. from cereals in Western Australia.

Pratylenchus quasitereoides n. sp. is described from Western Australia. It is characterized by 2 external incisures in the head cuticle, 4 lateral incisures at mid body, stylet length 17 µm to 19 µm, V greater than 75%, PUS less than 2 body diameters long and crenate tail terminus. Molecular data confirm the separation of the new species from morphologically similar and sympatric congeners. The host range also differs from P. teres as well as the sympatric P. neglectus, P. thornei and P. penetrans. Reproduction rates on oat and lupin differed between the new species and P. neglectus. The species was originally described as P. teres, but the species concept of P. teres now encompasses a considerable range of different attributes spread over two described subspecies and three variant populations. The new species differs from all these subspecies and populations in at least two characters. It differs from all populations of P. teres teres most notably in having four rather than 6 lateral lines and a more posterior vulva. It differs from P. teres vandebergae in having a longer stylet and longer overlap of the intestine by the oesophageal glands. Characters which can be used under low magnification to separate the new species from the closest sympatric congeners (P. thornei and P. crenatus) are discussed.

Incursion Management in the Face of Multiple Uncertainties: A Case Study of an Unidentified Nematode Associated with Dying Pines Near Melbourne, Australia

In late November 1999, dying pine trees were observed near the docks in Melbourne. The cause was initially identified as Bursaphelenchus xylophilus, the pinewood nematode. However, it was soon discovered that it was another nematode, Bursaphelenchus hunanensis, which was associated with the dying pine trees. Very little was known about the biology or pathogenicity of this species, except that it had never before been recorded in Australia. Other dying trees were soon discovered with the nematode, and deciding on an appropriate response became a critical issue. This paper describes the subsequent events in the face of the uncertainty regarding the pathogenicity of the nematode, its origin, its vector, and its biology, particularly dispersal. More general principles can be drawn from this experience regarding the management of incursions of pinewood and other nematodes. There may also be important lessons regarding spread of nematodes associated with wood and insects.

Bursaphelenchus hunanensis associated with dying Pinus species in Victoria, Australia

Bursaphelenchus hunanensis (Nematoda: Aphelenchida: Parasitaphelenchidae), identified morphologically in 2001, was associated with dying trees from several species of the genus Pinus at several locations around Melbourne, Victoria. This is the first record for Australia of this nematode and the first detection of this species outside China. The nematode was apparently eradicated through a targeted campaign and perhaps poor vectors. This success is significant because it demonstrates that eradication may be a viable strategy for dealing with incursions of exotic nematodes.

Nematodes from galls on Myrtaceae. VII. Fergusobia from 'leafy' leaf bud galls in Australia, with re-description of Fergusobia tumifaciens (Currie 1937) Wachek 1955 and descriptions of Fergusobia planchonianae n. sp. and Fergusobia viminalisae n. sp.

Fergusobia tumifaciens (Currie 1937) Wachek 1955, the type species for the genus Fergusobia, is re-described from specimens collected from leafy leaf bud galls on Eucalyptus bridgesiana near Albury in New South Wales, Australia. It is morphologically characterized by the combination of an open C-shaped parthenogenetic female with a small broadly conoid tail, a C-shaped infective female with a bluntly rounded tail tip, and an arcuate to J-shaped male with angular spicules, not heavily sclerotised, and short to mid-length peloderan bursa. Two new species of Fergusobia, collected from leafy leaf bud galls on, respectively, Eucalyptus planchoniana in Queensland, and E. viminalis in South Australia, Australia, are described. Fergusobia planchonianae Davies n. sp. is characterised by the combination of a C-shaped parthenogenetic female with a conoid tail, an arcuate infective female with an hemispherical tail tip, and an almost straight to arcuate to C-shaped male with an angular spicule, a long peloderan bursa and a narrow tail. Fergusobia viminalisae Davies n. sp. is characterised by the combination of an open C-shaped parthenogenetic female with a broadly conoid tail, a C-shaped infective female with a bluntly rounded tail tip, and an arcuate to J-shaped male with an angular (not heavily sclerotised) spicule and short to mid-length peloderan bursa. The shield morphologies of the fly larvae associated with the leafy leaf bud galls and their possible relationships are outlined. Possible evolutionary relationships of the Fergusobia nematodes from these galls are discussed, considering their morphology, DNA sequences, and the relationships of the associated Fergusonina flies and host plants.xa0

First record of stubby-root nematode (Paratrichodorus porosus) associated with barley in Australia

High populations (5000 to 20 000/kg soil) of the stubby-root nematode Paratrichodorus porosus were identified morphologically from soil samples taken under patches of poorly growing barley in a field between Yuleba and Surat in western Queensland, Australia. Lower populations (<4000/kg soil) were recovered from soil samples taken from asymptomatic barley. This is the first record of this nematode species on barley in Australia.

Dispersal of Potato Cyst Nematodes Measured Using Historical and Spatial Statistical Analyses

Rates and modes of dispersal of potato cyst nematodes (PCNs) were investigated. Analysis of records from eight countries suggested that PCNs spread a mean distance of 5.3 km/year radially from the site of first detection, and spread 212 km over ≈40 years before detection. Data from four countries with more detailed histories of invasion were analyzed further, using distance from first detection, distance from previous detection, distance from nearest detection, straight line distance, and road distance. Linear distance from first detection was significantly related to the time since the first detection. Estimated rate of spread was 5.7 km/year, and did not differ statistically between countries. Time between the first detection and estimated introduction date varied between 0 and 20 years, and differed among countries. Road distances from nearest and first detection were statistically significantly related to time, and gave slightly higher estimates for rate of spread of 6.0 and 7.9 km/year, respectively. These results indicate that the original site of introduction of PCNs may act as a source for subsequent spread and that this may occur at a relatively constant rate over time regardless of whether this distance is measured by road or by a straight line. The implications of this constant radial rate of dispersal for biosecurity and pest management are discussed, along with the effects of control strategies.

Molecular Phylogeny Inferred from 18S rRNA Gene Sequences of Nematodes Associated with Cernuella virgata, a Pest Snail in Australia

Pest snails are economically important pests of the grain industry. Nematode based bioagent appears to be a hope for controlling pest snails in an environment friendly way. Based on the dataset of 18S rRNA gene sequences, we propose a molecular phylogeny of nematodes baited with Cernuella virgata in soils collected from southern states of Australia. A total of 12 species (representing eight genera of nematodes) were identified and the inferred phylogenetic trees (Neighbor-Joining and Minium Evolution) placed them within three (I, IV and VII) out of the seven clades, indicating the possibility of multiple origins of snail parasitism. In Clade I and Clade VII, nematodes associated with Cernuella virgata formed sister group relationships with some slug – parasitic nematodes. We assume that snail – parasitic nematodes and slug - parasitic nematodes might share common ancestors in their evolutionary histories.

Bursaphelenchus hunanensis associated with dyingPinus species in Victoria, Australia

Bursaphelenchus hunanensis (Nematoda: Aphelenchida: Parasitaphelenchidae), identified morphologically in 2001, was associated with dying trees from several species of the genusPinus at several locations around Melbourne, Victoria. This is the first record for Australia of this nematode and the first detection of this species outside China. The nematode was apparently eradicated through a targeted campaign and perhaps poor vectors. This success is significant because it demonstrates that eradication may be a viable strategy for dealing with incursions of exotic nematodes.