The

World

of

Image: Courtesy of Thomas O. Powers, Ph.D. and Rebecca Higgins

NEMATODES

What are nematodes?What are nematodes?

• Unsegmented roundwormsUnsegmented roundworms

• Aquatic (Live in water)Aquatic (Live in water)

• SmallSmall

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?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” nematodesGood”-vs-“Bad” nematodes

• Bacterial feedersBacterial feeders

• Fungal feedersFungal feeders

• PredatorsPredators

• Animal-parasitesAnimal-parasites

• Plant-parasitesPlant-parasites

““Good guys”Good guys”

““Bad guys”Bad guys”

Predatory nematodesPredatory nematodes

MmmmTastes 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 roundwormsIntestinal roundworms

Ascaris lumbricoides

Image: Courtesy of Richard Cyr. On the world wide web at http://courses.bio.psu.edu/fall2005/biol110/tutorials/tutorial39.htm

HookwormHookworm

Image: Courtesy of Richard Cyr. On the world wide web at http://courses.bio.psu.edu/fall2005/biol110/tutorials/tutorial39.htm

Plant Parasitic NematodesPlant Parasitic Nematodes

Sting nematodes on soybeanSting nematodes on soybeanImage: 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– 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 lLab Mouse: Courtesy of Ellis Jensen, Ph.D.Nematode: Courtesy of TJ Bliss. May be copied for educational purposes.