Return to the Russian Journal of Nematology Home page

Volume 17, Part 1 (2009)

Chen Y.-H.

Using ecological niche modelling to predict geographical expansion of an invasive species Bursaphelenchus xylophilus in Asia

The potential distribution of Bursaphelenchus xylophilus in Asia was investigated through ecological niche modelling. The modelling procedure was developed based on night environmental variables. Principal component analysis was used to describe environmental niche differentiation of the species. The analysis identified temperature and precipitation as the most important factors affecting the invasiveness of B. xylophilus. This implied that water and energy played the dominant role in the potential spreading of B. xylophilus. No significant relationship was found between human population density and environmental niches exhibited by B. xylophilus. Further monitoring effect should be enhanced in those natural landscapes with moderate temperature and precipitation, for example, temperate zone in China, Japan and Korea. Areas with relatively low precipitation would suffer higher risk of the species as indicated by ecological niche visualization. Some areas in SW China will become highly susceptible to the species in the 2050 because of climate change. Controlling pest species Monochamus alternatus was a highly efficient surrogate for controlling B. xylophilus in the fieldwork. My findings contribute to further understanding the invasive ecology of B. xylophilus and have implications in sustainable integrated pest management practices.

Key words: Bursaphelenchus xylophilus; ecological niche modeling; GARP model; human population density; invasive species; principal component analysis.

Zoltowska K., Lopienska-Biernat E. and Rokicki J.

Activity of glycogen catabolism enzymes in Contracaecum rudolphii (Anisakidae)

Extracts of Contracaecum rudolphii L3 and L4 larvae, females and males were assayed for carbohydrate content and activities of enzymes that decompose glycogen and disaccharides. The sugar content was about 6-8% of nematode wet weight. In terms of their content, the saccharides assayed could be arranged in the following order: glycogen, glucose and trehalose. All carbohydrate concentrations were greater in females than in males. C. rudolphii shows activity of enzymes that decompose glycogen via phosphorolysis and hydrolysis. A high activity of glycogen phosphorylase (2.89 mmol mg-1) was recorded in the L3 larvae; the activity observed in the adults was lower by half. The amylase activities in all the forms of the parasite were relatively high and practically the same (0.163-0.175 U mg-1 and 0.93-1.03 µmol mg-1 for a-amylase and glucoamylase, respectively). Among disaccharidases (maltase, saccharase, lactase), the greatest activity was shown by maltase. It was particularly high (2.67 µmol mg-1) in the L3. The saccharase activity in these larvae was twice that of the adults. Lactase had the lowest activity (0.26- 0.49 µmol mg-1).

Key words:  Anisakidae; Contracaecum rudolphii; enzymes; metabolism of glycogen.

Fadeeva N.P. and Maslennikov S.I.

The abundance and distribution of free-living marine nematodes of the Piltun-Astokhskoye oil and gas field (North-East Sakhalin)

Although offshore oil and gas production platforms are a potential source for a number of toxic compounds, their impact on the meiofauna is insufficiently studied. In the vicinity of the oil and gas production platform MOLIKPAQ (North-East Sakhalin, the Sea of Okhotsk), the relative abundance of meiofauna assemblages ranged from 23.5 to 406.0 ind. 10 cm-2. The dominant group, nematodes, ranged from 6 to 385 ind. 10 cm-2. The maximum nematode density was at the distance of 250 m from the platform coupled with the highest petroleum hydrocarbons concentration (6.52 mg g-1) and the lowest values of the Shannon-Wiener diversity and PielouŐs evenness indices (1.25 and 0.33, respectively). In total, 69 nematode species were found. Disturbance in the structure of nematocenes, decrease of number species, drop of biological diversity indices, as well as increase in dominance of some nematode species of occurred in response to the introduction of PHCs as a stress factor. CLUSTER, MDS and SIMPER analyses clearly distinguished site groupings related to the different concentrations of PHC and sediment granulometry. The significant differences of nematode assemblages occurred in the response to the appearance of even low-level PHC contamination sediment. These results suggest that nematode assemblages can be used to detect non-catastrophic levels of oil contamination. Key words: Free-living marine nematodes, meiofauna, petroleum hydrocarbons, the Sea of Okhotsk.

Key words:  Free-living marine nematodes, meiofauna, petroleum hydrocarbons, the Sea of Okhotsk.

Holovachov O., Tandingan De Ley I., Mundo-Ocampo M., Gingold R., and De Ley, P.

Nematodes from the Gulf of California. Part 3. Three new species of the genus Diplopeltoides Gerlach, 1962 (Nematoda: Diplopeltoididae) with overviews of the genera Diplopeltis Gerlach, 1962 and Diplopeltula Gerlach, 1950

Three new species, Diplopeltoides axayacatli sp. n., D. santaclarae sp. n. and D. paramastigia sp. n., are described using light microscopy. All three species are morphometrically close to D. mastigia but the former differs in having a hook-shaped amphid, while the latter two can be distinguished from D. mastigia by having a gubernaculum with apophysis, and from each other by having, respectively, a striated cuticle (versus smooth) and a punctated interamphidial shield (versus crenate). The status and composition of Diplopeltoides is discussed and compared with those of Diplopeltis and Diplopeltula. The following species are transferred to different genera: Diplopeltula curta is placed in Pararaeolaimus; Diplopeltis bathmanni is placed in Diplopeltula; Diplopeltula pulcher and D. sundensis are transferred to Diplopeltoides. Three species of Diplopeltula are considered species incertae sedis: D. botula, D. striata and D. lucanica.

Key words: Baja California, Diplopeltis, Diplopeltoides axayacatli sp. n., Diplopeltoides paramastigia sp. n., Diplopeltoides santaclarae sp. n., Diplopeltula, morphology, morphometrics, SEM, taxonomy.

Tsalolikhin S. Ya. and ShoshinA. V.

Review of the genus Neotobrilus Tsalolikhin, 1981 (Nematoda, Enoplida: Tobrilidae)

The composition of the genus Neotobrilus was revised and new synonyms were established. Descriptions of a new species Neotobrilus sinensis sp.n. from Taiwan and a number of species from new localities are given. Some morphological characters as taxonomic ones are proposed. A species identification key is given.

Key words: morphology, morphometric, Neotobrilus identification key, Neotobrilus sinensis sp.n., taxonomy.

Trinh P. Q., la Pena E. de, Nguyen C. N., Nguyen H. X. and Moens M.

Plant-parasitic nematodes associated with coffee in Vietnam

Roots and soil were sampled in May 2005 from coffee plantations in fifteen localities of the seven coffee producing provinces of Vietnam for the presence of plant-parasitic nematodes on Coffea arabica and C. canephora. Twenty-one plant-parasitic nematodes species representing 14 genera were recovered from the rhizosphere soil. The endoparasitic nematodes Rotylenchulus reniformis, Meloidogyne spp., P. coffeae and R. arabocoffeae were predominant and occurred in 22%, 21%, 27% and 11% of all soil samples with 332, 257, 124 and 61 individuals/250 cm3 soil, respectively. Pratylenchus coffeae, R. arabocoffeae and Meloidogyne spp. were found in 24%, 9% and 12% of all root samples, respectively. Pratylenchus coffeae was present in root samples from 11 of the 15 localities, while Meloidogyne occurred in root samples from 9 localities but was present in soil samples from 12 localities. Root-knot nematodes were not found in root and soil samples from the Northern region (Muong Ang and Son La) and Dak Doa. Radopholus arabocoffeae was not detected in samples from localities from Northern and Centre of Vietnam, but was only present in some of the Western Highlands localities. Plant-parasitic species recorded for the first time in Vietnam in association with coffee were Hoplolaimus chambus, Xiphinema elongatum, Diphterophora perplexans, Apratylenchus vietnamensis and A. binhi. The occurrence of the main nematode genera varied across clusters of soil texture. Samples with high numbers of Meloidogyne spp. were grouped in clay soils, whereas R. arabocoffeae occurred in sandy and loamy soils indistinctively. Pratylenchus spp. and R. reniformis were present in large numbers in sandy soils.

Key words:  Coffea arabica, Coffea canephora, endoparasitic nematodes, soil characteristics, plant age.