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First Report of Trichodorus similis from the Czech Republic (Nematoda: Trichodoridae)

Members of the Trichodoridae can cause substantial crop losses directly by feeding on plant roots and indirectly as vectors of tobraviruses; both vector and virus are polyphagous. Although trichodorid nematodes are important pests of agricultural crops, no data are available on the presence or extent of these nematodes in the Czech Republic. In June 2005, three soil samples from the rhizosphere of a Quercus sp. at Cerveny Vrch yielded a population of Trichodorus similis Seinhorst, 1963. Specimens were extracted from soil by a decanting-sieving method, heat killed, and fixed in triethanolamine formalin (TAF), and processed and mounted in anhydrous glycerin. Nematodes were identified by morphological and morphometrical characters (2). Classical identification of these nematodes was further verified by molecular study. A single, male specimen was temporarily mounted in distilled water on a glass slide and relaxed with gentle heat. Measurements and photographs were taken, and the specimen was transferred to a 0.5-ml Eppendorf tube containing 0.25 M NaOH. Total genomic DNA was prepared by a rapid technique (4). Morphometric data of the male specimen used for DNA study are: body length 867 μm; body width 81 μm; onchiostyle length 44 μm; spicule length 36 μm; distance of anterior cervical papilla (CP)1 from anterior end 39 μm, CP1 to CP2 25 μm, CP2 to CP3 22 μm; posterior precloacal supplement (SP1) to cloacal opening 27 μm, distance SP1 to SP2 32 μm, distance SP2 to SP3 39 μm. The following primers were used in the PCR reaction: species-specific sense primer SIMIREV2 (5′-CACTCGTCGGACTCAAACC-3′) and universal antisense primer UNIVERSAL (5′-CCCGTCGCTACTACCGATT-3′) (1). A single fragment of approximately 452 bp was amplified. The D2 and D3 expansion regions of the large subunit 28S rDNA were amplified using the primer D2A (5′-ACAAGTACCGTGAGGGAAAGTTG-3′) and D3B (5′-TCGGAAGGAACCAGCTACTA-3′ (3). The region was sequenced after purification of PCR products from the gel slice with a Qiagen gel purification kit (Qiagen Inc., Valencia, CA). The obtained sequence was deposited in Genbank (Accession No. DQ832183). The obtained sequence was compared by BLAST in NCBI and the results showed strong similarities with T. similis (Accession No. AM180730). To our knowledge, this is the first report of T. similis associated with a deciduous forest in the Czech Republic. Taking into account the agricultural importance of trichodorids and tobraviruses as plant pathogens, there is a need for a comprehensive survey of these taxa in the Czech Republic. The damage level threshold is in the case of virus vector species equivalent to a single nematode. Therefore, information on these plant parasites would be useful for developing nematode management strategies.

References: (1) K. Boutsika et al. Plant Pathol. 53:110, 2004. (2) W. Decraemer and P. Baujard. Fundam. Appl. Nematol. 21:37, 1998. (3) P. De Ley et al. Nematology 2:591, 1999. (4) J. M. Stanton. Australas. Plant Pathol. 27:112, 1998.