Nematode Workshop 1 st Morning Session Nematology 101

Nematode Workshop 1 st 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/

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/)

Abundance of soil animals per square meter in European grassland

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

Sensory organs ü No eyes, appendages or segmentation ü Mechanosensory ü 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.

Phytonematode anatomy & morphology ü Well developed digestive & reproductive & sensory systems ü Lack circulatory & respiratory systems

Nematode identification Pratylenchus Xiphinema Criconemella

Physiological versatility ü Tolerate harsh habitats avoid interspecific competition and many environmental selection pressures ü Regulate uptake of O 2 between 100 to 5% ü Permeable, hydrostatic skeleton osmoregulation of Ca, Mg, K ü Tolerate p. H from 1. 6 to 11. 0 ü Temperatures from sub-zero to 60 C +

Survival Aphelenchus, anhydrobiosis

Head structures of soil nematodes a) bacterivore b) bacterivore c) bacterivore, predator d) Fungivore and/or herbivore e) omnivore f) herbivore g) herbivore h) predator

Predatory nematodes ü May feed on nematodes, protozoa, bacteria, etc Figure 5. Teeth of oral opening of predator Mylonchulus montanus (1000 x magnification), collected in soil with big blue stem in the Konza Prairie (96 W 35’ 39 N 05’) near Manhattan, Kansas. Photograph is provided courtesy of Peter Mullin/2000.

Bacterial-feeding nematodes ü Simple tubular mouthpart ü Elaborate cuticle around oral opening Figure 4. Cuticle ornamentation of oral opening of Acrobeles ctenocephalus (1000 x magnification), collected in soil with little bluestem (Andropogon scoparius) in the Konza Prairie (96 W 35’ 39 N 05’) near Manhattan, Kansas. Photograph is provided courtesy of Peter Mullin/2000. Paulo Vieira (Mactode publications)

Plant-parasitic nematodes ü Respond to CO 2 & root exudates ü Move few cm per day ü Probe with stylet ü Ecto-parasites ü Endo-parasites ü Lifecycle: 3 weeks (rootknot) to 2 yrs + (dagger) Figure 3. Variation in morphology of spear-like structure in oral opening a) male plant-parasite Hoplolaimus galeatus (1000 x magnification) collected from soil with big bluestem (Andropogon gerardii Vitman) in the Konza Prairie (96 W 35’ 39 N 05’) near Manhattan, Kansas, and b) female fungivore Enchodelus hopedorus (400 x magnification) collected from the summit of Long’s Peak, Colorado (105 W 35’ 40 N 16’). Photographs are provided courtesy of Peter Mullin/2000.

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

Major impacts of nematodes ü Decomposition of organic matter and recycling of nutrients (soil food web)

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

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

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

Morphology and relative size of major plant -parasitic nematodes Agrios

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)

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

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

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

Lifecycle of Pratylenchus penetrans – Root-lesion nematode Agrios

Plant productivity losses Meloidogyne, Root knot nematode damage

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

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