Phylum Nematoda

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Phylum Nematoda

• Most abundant animal on earth
• Diverse
• Important role in
• Decomposition and nutrient cycling
• Human health
• Agriculture (animal and plant)
• Science
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Nematodes that live in soil are -
microscopic - transparent
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stylet
reproductive system
esophagus
intestine
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Plant parasitic nematodes have stylets
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Microbivorous nematodes have open stoma
(mouth)
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ectoparasitic nematodes - only the stylet enters
roots
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• endoparasitic nematodes
• enter into the root and feed from the inside
• sedentary root knot and cyst
  nematodes
• migratory root lesion
  nematodes

female
egg mass
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Sedentary Endoparasites
All sedentary endoparasites have specialized
feeding sites in the root.
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• root knot nematodes Meloidogyne spp.
• vegetable and ornamental crops
• 4 major species
• (many more)

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root-knot affects both quality and yield
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root knot female (on the head of a pin)
egg
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juvenile stages female
juvenile male
adult stages
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nematode feeds on 4-6 giant cells
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Diagnosing a root knot nematode problem
Which plants are infected with root knot nematode?
symptoms sign
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sign root knot egg masses stained red
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cyst nematode Heterodera spp.
Many species - narrow host range - named for
primary host
SCN Management Guide
cyst dead body of female
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SCN is the most important disease of soybean in
the U.S.
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susceptible cultivar on left / resistant on right
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Heterodera glycinessoybean cyst nematode
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J3
J2
nematode feeding cells
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soybean cyst nematode Heterodera glycines
SCN
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Symptoms stunting, chlorosis, patchy
distribution in field