Extraction of Nematodes by
Decanting and
Sieving - Method 1
Materials
|
Source
|
- 20-mesh sieve (833-µm aperture)
- 200-mesh sieve (74-µm aperture)
- 325-mesh sieve (43-µm aperture)
- Coarse sieve (1 cm aperture)
- Two stainless steel bowls or
plastic buckets
- 250 ml beaker:
- 600 ml beaker
- Coarse spray wash bottle or tube attached to
faucet
|
Department of Entomology and Nematology
|
Procedure
- 1. Review potential extraction
errors.
-
- 2. Mix soil sample and pass through coarse
sieve to remove rocks, roots, etc.
-
- 3. Take a 600 cc subsample of soil: pack
lightly into beaker for uniformity.
-
- 4. Place soil in one of the buckets or pans;
half fill with water.
-
- 5. Sieving and decanting process (various
combinations of the following):
- a) Mix soil and water by stirring with hand or
paddle; allow to stand until water almost stops swirling.
- b) Pour all but heavy sediment through 20-mesh
sieve into second bucket; discard residue in first bucket;
discard material caught on sieve.
- c) Stir material in second bucket; allow to
stand until water almost stops swirling.
- d) Pour all but heavy sediment through 200-mesh
sieve into first bucket; discard residue in second bucket.
- e) Backwash material caught on 200-mesh sieve
(which includes large nematodes) into 250-ml beaker.
- f) Stir material in first bucket; allow to
stand until water almost stops swirling.
- g) Pour all but heavy sediment through 325-mesh
sieve into second bucket; discard residue in first bucket.
- h) Backwash material caught on 325-mesh sieve
(which includes small to mid-sized nematodes and silty material)
into 250-ml beaker.
-
- 6. Sample in 250 ml beaker will probably be too
dirty for direct viewing; sample may be placed on Baermann Funnel
or subjected to sucrose-centrifugation. The combined procedure
allows extraction of nematodes from larger volumes of soil.
Extraction of Nematodes by
Decanting and
Sieving - Method
2
Materials
|
Source
|
- 60-mesh sieve (246-µm aperture)
- 325-mesh sieve (43-µm aperture)
- Coarse sieve (1 cm aperture)
- Two plastic or metal pitchers (2 liter volume)
- Plastic or metal pitcher (3 liter volume)
- Two 250 ml beakers
- Coarse spray wash bottle or tube attached to
faucet
|
Department of Entomology and Nematology
|
Procedure
- 1. Review potential extraction
errors.
-
- 2. Mix soil sample and pass through coarse
sieve to remove rocks, roots, etc.
-
- 3. Take a 250 cc subsample of soil: pack
lightly into beaker for uniformity.
-
- 4. Place soil in one of the 2 liter pitchers;
half fill with water.
-
- 5. Sieving and decanting process (various
combinations of the following):
- a) Mix soil and water by stirring.
- b) Pour the soil and
water slurry back and forth between the two 2-liter pitchers five times
to separate nematodes from soil particles.
- c) Pour all but heavy sediment through 60-mesh
sieve into the 3-liter pitcher.
- d) Half-fill the
2-liter pitcher with water and repeat steps b and c twice.
- c) Stir material in 3-liter pitcher; allow to
stand until water almost stops swirling.
- d) Pour all but heavy sediment through 325-mesh
sieve into first bucket; discard residue in pitcher.
- e) Backwash material caught on 325-mesh sieve
into 250-ml beaker.
-
- 6. Sample in 250 ml beaker will probably be too
dirty for direct viewing; sample may be placed on Baermann Funnel
or subjected to sucrose-centrifugation. The combined procedure
allows extraction of nematodes from larger volumes of soil.
Extraction of Nematodes by the Baermann
Funnel Technique
Materials
|
Source
|
- Glass funnels (12.5 cm diam.)
- Wire-mesh baskets (10 cm diam.,
5-10-mm aperture)
- Rubber tubing
- Kimwipes or facial tissue
- Ring stand
- Tubing clamps
- Coarse sieve (1 cm aperture)
- 250 ml beakers
- 50 ml beakers
- Two water bottles, coarse and fine
spray
|
Department of Entomology and Nematology
|
Procedure
- 1. Review potential extraction
errors.
-
- 2. Attach 10-cm length of rubber tubing to
funnel stem and clamp tubing.
-
- 3. Mount funnel on ring stand.
-
- 4. Fill funnel two-thirds full with water.
-
- 5. Place wire-mesh basket in top of funnel and
use it to support tissue.
-
- 6. Mix soil sample and pass through coarse
sieve to remove rocks, roots, etc.
-
- 7. Spread soil subsample (50 cc soil) evenly on
tissue; fold in edges of tissue.
-
- 8. Complete filling funnel with water so that
water level is about 5 mm above wire-mesh; do not let water and
soil lose contact during extraction period - add water as needed.
-
- 9. Maintain temperature at 22-25 C so that it
is conducive to nematode movement.
- Note nematodes move through tissue and settle
in funnel; only active stages are recovered.
-
- 10. After 48 h, recover extracted nematodes by
releasing 20 ml of water from stem of funnel into a counting
dish.
Extraction of Nematodes by Sieving and
Sucrose-Centrifugation
Materials
Materials
|
Source
|
- 20-mesh sieve (833-µm aperture)
- 500-mesh sieve (25-µm aperture)
- 635-mesh sieve (20-µm aperture)
- Coarse sieve (1 cm aperture)
- Two 600-ml plastic beakers
- Centrifuge tubes (must be a set)
- Funnel
- Spatula
- Test tube rack
- Sugar
- Two water bottles, coarse and fine
spray
|
Department of Entomology and Nematology
|
Procedure
- 1. Review potential extraction
errors.
-
2. Prepare sucrose solution: to 454 g sugar add
de-ionized water to bring total volume to 1 liter. Stir until
sugar is completely dissolved.
-
3. Mix soil sample and pass through coarse
sieve to remove rocks, roots, etc.
-
4. Take a 100 cc subsample of soil: pack
lightly into beaker for uniformity.
-
5. Remove sand and organic material:
- a) Mix soil subsample in 500 ml water by
pouring between beakers ten times.
- b) Rinse residues in second beaker into beaker
with sample.
- c) Swirl beaker with sample; allow to stand for
15 seconds (sand settles).
- d) Pour supernatant through 20/500-mesh stacked
sieves.
- e) Gently tap side of 500-mesh sieve to
facilitate drainage.
- Note: Larger particles will remain in beaker;
organic debris is caught on 20-mesh sieve; nematodes and silt are
retained on 500-mesh sieve.
- f) Using the coarse-spray water bottle, gently
wash nematodes, etc. into one sector of the 500-mesh sieve.
- g) Using the fine spray water bottle, wash
sample into a centrifuge tube.
-
6. Centrifuge: add water to centrifuge tubes to
equalize volumes; place tubes in centrifuge in balanced pairs.
- a) Spin at 1700 rpm (810 g) for 5 minutes
without using the brake.
- b) Allow to settle for 5 minutes.
- c) Aspirate supernatant to approximately 1 cm
above pellet.
- d) Fill tubes with sucrose solution at room
temperature.
- e) Stir with a spatula to break up pellet (must
be completely dispersed).
- f) Spin sample: bring centrifuge up to 1000 rpm
( 280 g) in 30 sec, then apply brake.
- Note: Nematodes and clay are suspended in
sucrose supernatant; silt and larger particles are in the pellet.
-
7. Pour supernatant through 635-mesh sieve.
Rinse gently with water and transfer to labeled vials using the
fine spray water bottle.
(Method modified by Dr. Bruce Jaffee,
Department of Nematology, UC Davis, from Jenkins 1964, Pl. Dis.
Reptr. 48:692.)
General Reference on extraction methods:
Barker, K.R.
1985. Nematode extraction and bioassays. Pp 19-35 in K.R. Barker, C.C. Carter
and J.N. Sasser (eds) An Advanced Treatise on Meloidogyne, Volume 2.
Methodology. North Carolina State University Graphics.
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