Nematology 101: Biology and Ecology

1. Nematode Workshop 1st Morning Session Nematology 101: Biology and Ecology Deb Neher University of Vermont Dept. of Plant and Soil Science deborah.neher@uvm.edu http://www.uvm.edu/~dneher/

2. Soil Biological Indicators Lab Dr. Deborah Neher uses soil nematode & microarthropods for monitoring soil quality and measuring progress of soil remediation (http://www.uvm.edu/~dneher/)

3. Abundance of soil animals per square meter in European grassland

4. Aquatic Unsegmented Appendageless Transparent Bilaterally symmetrical Generally bisexual Vermiform roundworms Non-coelomate Biotrophs General characteristics of nematodes Meloidogyne hapla

5. Sensory organs • No eyes, appendages or segmentation • Mechanosensory • Chemosensory Fig. 2. Spiral-shaped chemosensory organs called amphids in an anterior position of Achromadora sp. collected from soil of Jumbo Valley fen in Cherry County, Nebraska.

6. Well developed digestive & reproductive & sensory systems • Lack circulatory & respiratory systems Phytonematode anatomy & morphology

7. Nematode identification Pratylenchus Xiphinema Criconemella

8. Physiological versatility • Tolerate harsh habitats avoid interspecific competition and many environmental selection pressures • Regulate uptake of O2 between 100 to 5% • Permeable, hydrostatic skeleton osmoregulation of Ca, Mg, K • Tolerate pH from 1.6 to 11.0 • Temperatures from sub-zero to 60C +

9. Survival Aphelenchus, anhydrobiosis

10. Head structures of soil nematodes • bacterivore • bacterivore • bacterivore, predator • Fungivore and/or herbivore • omnivore • herbivore • herbivore • predator

11. Predatory nematodes • May feed on nematodes, protozoa, bacteria, etc Figure 5. Teeth of oral opening of predator Mylonchulus montanus (1000x magnification), collected in soil with big blue stem in the Konza Prairie (96W35’ 39N05’) near Manhattan, Kansas. Photograph is provided courtesy of Peter Mullin/2000.

12. Bacterial-feeding nematodes • Simple tubular mouthpart • Elaborate cuticle around oral opening Figure 4. Cuticle ornamentation of oral opening of Acrobeles ctenocephalus (1000x magnification), collected in soil with little bluestem (Andropogon scoparius) in the Konza Prairie (96W35’ 39N05’) near Manhattan, Kansas. Photograph is provided courtesy of Peter Mullin/2000. Paulo Vieira (Mactode publications)

13. Plant-parasitic nematodes • Respond to CO2 & root exudates • Move few cm per day • Probe with stylet • Ecto-parasites • Endo-parasites • Lifecycle: 3 weeks (root-knot) to 2 yrs + (dagger) Figure 3. Variation in morphology of spear-like structure in oral opening a) male plant-parasite Hoplolaimus galeatus (1000x magnification) collected from soil with big bluestem (Andropogon gerardii Vitman) in the Konza Prairie (96W35’ 39N05’) near Manhattan, Kansas, and b) female fungivore Enchodelus hopedorus (400x magnification) collected from the summit of Long’s Peak, Colorado (105W35’ 40N16’). Photographs are provided courtesy of Peter Mullin/2000.

14. Plant-parasitic nematodes con’t • Generalists or specialists • Hosts range from 1 to 100’s • All crop plants are susceptible to at least one nematode species • Most are root parasites but species have adapted to parasitize most plant tissues • More damage can be associated with coarser textured soils – sands (larger pore space)

15. Major impacts of nematodes • Decomposition of organic matter and recycling of nutrients (soil food web)

16. Major impacts of nematodes • Decomposition of organic matter and recycling of nutrients (soil food web) • Biological control agents, esp. for insects • Research biological models • Diseases of animals and humans (heartworm, Trichinosis, hookworm, etc.) • Important plant pathogens

17. Other nematodes... • Animal parasites • Human: Night blindness, Elephantiasis • Pets: Hookworm • Insects: biocontrol • Caenorhabditis elegans • Model system • Studies of aging, neurology, ecotoxicology

18. Major impacts of nematodes • Decomposition of organic matter and recycling of nutrients (soil food web) • Biological control agents, esp. for insects • Research biological models • Diseases of animals and humans (heartworm, Trichinosis, hookworm, etc.) • Important plant pathogens

19. Morphology and relative size of major plant-parasitic nematodes Agrios

20. Types of Plant-Pathogenic Nematodes Ectoparasites:feed from outside the plant Migratory:moves, feeding from plant to plant (dagger) Sedentary:remains on same plant (spiral) Endoparasites:feed from inside the plant Migratory:moves within and feeds on tissues (lesion) Sedentary:remains within same plant and feeds at specialized sites (root-knot)

21. Sedentary ectoparasite (spiral) Migratory ectoparasite (dagger) Essential Plant Pathology, 2006 NC State Univ. Sedentary endoparasite (root-knot) Migratory endoparasite (lesion)

22. Typical lifecycle of a plant-parasitic nematode M M M H M

23. Meloidogyne hapla 3rd stage juvenile 4th stage juvenile Formation of giant cells and galls J2 infect root Egg mass 2nd stage juvenile (J2) mobile in soil Egg 1st stage juvenile Modified from Agrios, 1997

24. Lifecycle of Pratylenchus penetrans – Root-lesion nematode Agrios

25. Plant productivity losses Meloidogyne, Root knot nematode damage

26. How do nematodes damage plants? • Direct feeding on plants (metabolic sinks) • Malformation of host tissues (morphological & physiological) • Predispose host plant to physical stress • Provide entry for secondary pathogens (disease complexes) • Breakdown of resistance to other pathogens • Vectoring of plant pathogens (virus & bacteria) • Suppression of beneficial organisms

27. Nematology 101: Biology and Ecology Questions? Coming up next...signs and symptoms