Transcript No Slide Title

The
World
of
NEMATODES
Image: Courtesy of Thomas O. Powers, Ph.D. and Rebecca Higgins
What are nematodes?
• Unsegmented roundworms
• Aquatic (Live in water)
• Small
Nematode Management for Nursery Crops (Ornamentals and Planting Stock of Fruits and Nuts), 2005 UF/IFAS. On the web a http://edis.ifas.ufl.edu/NG011
Where do nematodes live?
Image: Redrawn by Becky Westerdahl from Ayoub, S.M. 1977. Plant nematology an agricultural training aid. Sacramento California Department of Food and Agriculture, Division
of Plant Industry. On the world wide web at http://ucdnema.ucdavis.edu/imagemap/nemmap/Ent156html/intro/WHERE.GIF
“Good”-vs-“Bad” nematodes
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Bacterial feeders
Fungal feeders
Predators
Animal-parasites
Plant-parasites
“Good guys”
“Bad guys”
Predatory nematodes
Mmmm
Tastes like
chicken!!
Image: Courtesy of John Chitambar. On the world wide web at http://ucdnema.ucdavis.edu/imagemap/nemmap/ENT156HTML/slides/fromCD/0847/025B.GIF
Intestinal roundworms
Ascaris lumbricoides
Image: Courtesy of Richard Cyr. On the world wide web at http://courses.bio.psu.edu/fall2005/biol110/tutorials/tutorial39.htm
Hookworm
Image: Courtesy of Richard Cyr. On the world wide web at http://courses.bio.psu.edu/fall2005/biol110/tutorials/tutorial39.htm
Plant Parasitic Nematodes
Sting nematodes on soybean
Image: Sting Nematode, Belonolaimus longicaudatus Rau (Nematoda: Secernentea: Tylenchida: Tylenchina: Belonolaimidae: Belonolaiminae),
2005 UF/IFAS. On the web a http://edis.ifas.ufl.edu/IN395
Entomopathogenic Nematodes
and their Bacterial Associates
• The Nematode:
– Soil dwelling, aquatic organism
• The Bacterium:
– Motile, lives in the nematode gut
• Nematode + Bacterium
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Obligate, mutualistic symbionts
Lethal parasites of insects
Can infect many different insects
Found everywhere on earth
Steinernema image: Courtesy of Thomas O. Powers, Ph.D. and Rebecca Higgins. May be copied for educational purposes.
Bacterial image: Courtesy of TJ Bliss. May be copied for educational purposes.
Xenorhabdus (bacterium)
lives in
Steinernema (nematode)
Photorhabdus (bacterium)
lives in
Heterorhabditis (nematode)
Steinernema image: Courtesy of Thomas O. Powers, Ph.D. and Rebecca Higgins. May be copied for educational purposes.
All other images: Courtesy of TJ Bliss. May be copied for educational purposes.
Steinernema and Heterorhabditis
• Nematodes enter insect
through natural openings
• Once in the insect, the
nematode releases the bacteria
that are carried in the intestine
• Bacterial cells reproduce
rapidly and kill the insect
within 24-48 hours using
many different toxins.
• The nematodes eat the
bacteria and reproduce for 3
or 4 generations
• Over 100,000 nematodes exit
the insect
Xenorhabdus and
Photorhabdus
• Produce enzymes and highly potent
insect toxins
• Produce antibacterial and antifungal
antibiotics
• Photorhabdus produces enzymes
that cause it to glow in the dark
Image: Courtesy of TJ Bliss. May be copied for educational purposes.
Model Organisms
• Primates
• Rats and Mice
• Nematodes!!!
Primate: Courtesy of David Bygott. On the world wide web at http://www.tolweb.org/treehouses/?treehouse_id=3029 l
Lab Mouse: Courtesy of Ellis Jensen, Ph.D.
Nematode: Courtesy of TJ Bliss. May be copied for educational purposes.