Extraction of Xiphinema and Longidorus species from soil by a modification of Cobb's decanting and sieving technique*

Abstract

A modification of Cobb's decanting and sieving technique is described which was found to combine speed of operation with efticiency when extracting Xiphinema and Longidorus species from a variety of soils. Standard times were set for sedimentation and the nematodes were collected on a bank of sieves each of 150 , u aperture (rather than of a range of apertures) before final separation from inert debris on a Baermann funnel.Preliminary tests showed that both time and temperature could have considerable effect on yield during the final separation stage. X . diversicaudaturn and X . vuittenexi showed different temperature optima at which * This work formed part of a thesis approved for the award of a Ph. D. in the University of London. t Now at Plant Pathology Laboratory, Hatching Green, Harpenden, Herts.

Interactions between mycophagous nematodes, mycorrhizal and other soil fungi

“…In another study with a modified Baermann funnel method, storage temperature had variable effects on the recovery of different species of nematodes and the difference in numbers recovered in two locations were attributed to the temperature difference between the locations (Kerr & Vythilingam 1966). This is in agreement with the results of Flegg (1967) who concluded that the optimum temperature for extraction yields of two species of Xiphinema was directly related to their geographical distribution. A north European species had an optimum of 14-20 °C whereas the yield of a mediterranean species increased up to 25 T. Barker, Nusbaum & Nelson (1969a) studied the seasonal differences in numbers of nematodes using three extraction procedures.…”

“…Sohlenius (1980) proposed that the IIaenmann funnel was the best technique if small samples were processed. However, lack of oxygen at the bottom of the funnel neck of the original apparatus as described by Baermann resulted in loss of activity of the nematodes which collected there (Flegg 1967) and in some cases, no nematodes were collected from the bottom of the funnel because they lodged on its inclined surfaces (Minagawa 1979). The modifications of the Baermann funnel proposed by Whitehead & Hemming (1965) and Townshend (1963) may have corrected these faults by replacing the funnels with shallow trays or pans which may allow better oxygenation of the water and avoid losses on the inclined walls of the funnel.…”

“…In another study with several species of Xiphinema, an average of 72% of a 48 hour yield was obtained after 6 hours and 94% after 20 hours (Flegg 1967 (Viglierchio & Schmitt 1983a).…”

“…However, it may be difficult to extract nematodes from soils in which they have lived for long periods of time (see Flegg 1967;McSorley 1987). …”

Molecular and Morphological Characterization of Xiphinema chambersi Population from Live Oak in Jekyll Island, Georgia, with Comments on Morphometric Variations

“…to a 20-cm-depth) were collected from the root zone around live oak (Q. virginiana) trees on Jekyll Island, GA. Nematodes were extracted from a 200-cm 3 composite soil sample that was thoroughly but gently mixed, using the technique of Flegg (1967) with modifications by Fraedrich and Cram (2002). Nematodes were removed from Baermann funnels, and juveniles and females were fixed in warm 3% formaldehyde fixative and processed to glycerine by the formalin-glycerine method (Hooper, 1970;Golden, 1990).…”