INTRODUCTION TO NEMATODES E.C. McGawley1, C. Overstreet2, M.J. Pontif3 and A.M. Skantar4 (1-3)Nematologists, LSU AgCenter, Baton Rouge, LA 70803 and 4Research Molecular Biologist, USDA-ARS Nematology Laboratory, Beltsville, MD 20705 (July, 2011) This document contains slide numbers, comments on content where necessary, and explanations for abbreviations used on slides in this presentation, “Introduction to Nematodes.” Credits for materials that are not acknowledged on slide number 122 are included herein. All elements associated with this presentation are for use for non-profit, educational purposes in the fields of plant nematology, plant pathology and related plant protection and helminthology disciplines. The primary vehicles for the dissemination of this presentation are anticipated to be The Society of Nematologists and The Organization of Nematologists of Tropical America. Users and viewers are urged to visit the websites of these two organizations (http://www.nematologists.org and http://ontaweb.org) to learn more about their contributions to science and agriculture and to become familiar with the philanthropic activities of the N.A. Cobb and ONTA Foundations. Materials in this presentation are focused primarily on nematodes that are parasitic on agriculturally important plants. Observers and narrators of this presentation should be mindful of and convey to audiences the great diversity and immense importance of other members of this unique assemblage of animals, certainly given unjustifiably minor emphasis herein, grouped into Nematoda. Feedback from users of this presentation is encouraged via the email contacts at the end of this document. Contributions of photographs or formatted data that improves existing sections or adds new sections on nematodes other than those that are plant parasites are most welcome. This presentation should NOT be considered a FINISHED product. Hopefully, with contributions from individuals interested in nematodes, it will evolve into an ongoing project that reflects the biological, ecological, and scientific knowledge accumulated about nematodes and their roles in nature. 1.) Introduction. The purpose of this introductory slide is to convey the fact that nematodes inhabit almost every known ecological niche on earth. Nematodes are among, if not the, most abundant multicellular animals on earth. The first invertebrates appeared ca. 600 million years ago; with fossilized specimens from amber in Lebanon indicating the first nematodes (insect parasitic mermithid nematodes) from 135-120 million years ago (Poinar, G.O. et al. 1994. Fundam. Appl. Nematol., 17(5) 475-477). 2.) The Six Kingdoms. Data here illustrate the abundance and groupings of living things on earth from the “Tree of Life web project” (http://tolweb.org/tree/). Note   1 that animals account for one million of the 1.5 million living things described to date. 3.) Worms. Establishing the relative positions of worms and worm-like creatures within the kingdom Animalia. Animals display either radial or bilateral symmetry. Bilaterally symmetrical organisms are either deuterostomes or protostomes and the first “Build-in” explains these terms and provides the embryology necessary for an understanding of the formation of the mesoderm tissue present in a triploblastic organism. Both worms and worm-like animals are protostomes and divide into two “superphyla:” those that contain “animals with external cilia and/or filter combs” (Lophotrochozoa) and those that “molt and have cuticles” (Ecdysozoa). Details are at http://www.wormbook.org/toc_nematodeevolecol.html in the second chapter by Paul DeLey. There are nine phyla (Platyhelminthes, Bryozoa, Sipuncula, Mollusca, Nemertea, Entoprocta, Annelida, Phoronida and Brachiopoda) of Lophotrochozoa and eight phyla (Arthropoda, Onychophora, Tardigrada, Nematomorpha, Kinorhyncha, Loricifera, Priapulida and Nematoda) of Ecdysozoa. From this point, Build-in 2 shows the (cestode) tapeworm, Taenia pisiformis, it’s anterior end (scolex), attached to the intestine of a rabbit (www.thiagoodview.com). 4.) Phylum Nematoda. The six Build-ins introduce characteristics of animals in the phylum Nematoda. The terms coelomate, pseudocoelomate and acoelomate are explained in Build-in 1. Note: Some experts contend the Pseudocoelomata is an artificial paraphyletic group. However, the pseudocoelom is still a character of nematodes and is presented here only for an overview and is not meant to endorse the phylogenetic validity of the group. 5.) Animal Parasites. Top right: river blindness caused by Onchocerca volvulus. This nematode is vectored by the blackfly, Simulium damnosum; Center right: Toxocara canis, the dog roundworm; Bottom right: Toxocara cati from common house cat (modified from petcaregt.com/cat-worm.html); Bottom left: heartworm, Dirofilaria immitis; Top left: the hookworm, Ancyclostoma duodenale; Build-ins: 1.) the nematode, Loa loa, being removed from the eye; 2.) the Guinea worm, Dracunculus medinensis, being removed from a foot; 3.) the symbol of medicine, the caduceus, said by some to represent the Guinea worm and a tool used for its removal from a human (note: outside of America, many professional and patient centered organizations use the staff of Asclepius that has a single serpent encircling the staff as their symbol); 4.) swollen leg of an individual infected with the elephantaisis nematode, Wuchereria bancrofti; 5.) biblical references to nematode infections by the Guinea worm, Dracunculus medinensis and human cutaneous larval migrans caused by the hookworms Ancylostoma duodenale and Necator americanus; 6.) colorized ascarid poultry worm. 6.) Free-Living Species. Top right: electron micrograph of anterior of Acrobeles sp.; Center right: Caenorhabditis elegans; Bottom right: Mononchus sp. feeds on another nematode; Bottom center: video; Left: Dorylaimus sp.; Build-ins: 1 A.) Thoracostoma sp.; B.) Acromoldavicus mojavicus; C.) Enoploides sp.; D.)   2 Pontonema cf. parpapilliferum; E.) Ceramonema sp.; F.) Latronema sp.; G.) Actinca irmae; 2.) Mononchus sp. feeds on another nematode. 7.) Marine Inhabitants (including parasites of marine fauna). Top right: Rhabditis sp.; Bottom right: Eustrongyloides sp. from the Northern Snakehead fish, Channa argus; Bottom center: Trissonchulus sp.; Bottom left: drawing of a male Glochinema bathyperuvensis (dpc.uba.uva.nl); Middle left: Onyx sp.; Top left: unknown marine species (www.arcodiv.org); Build-in: (top) Phocanema sp. lying on fish filet; (bottom): anterior of Camallanus cotti. 8.) Plant Parasites. Top left: (red esophagus) colorized illustration from B.Y. Endo; Build-ins 1-6: major characteristics of plant parasitic nematodes; 7.) diagram illustrating the relative sizes of the most common genera of plant parasitic nematodes (modified from Plant Pathology by G.N. Agrios, 5th Edition, 2005, Elsevier Academic Press); 8.) preliminary introduction to nematode anatomy. Note: Some experts contend that 90% of nematodes are marine, making plant and animal parasites by comparison a tiny minority. Additionally, students should be aware that most plant parasitic nematodes are not agricultural pests but simply a part of natural ecosystems. 9.) Etiological Agents of Plant Diseases. For each pathogen group, the chronological order of discovery, the first disease and discoverer are presented. (Model: available from Mactode Publications). Cell diagram from Plant Pathology by G.N. Agrios, 5th Edition, 2005, Elsevier Academic Press. 10.) The Tool of the Trade. C= cone, S= shaft and K= knob. DEGO= dorsal esophageal gland orifice, EL= esophageal lumen, A= ampulla. Build-out: stylet overlays. Build-ins: 1.) functions of the stylet; 2.) note of caution; 3.) Illustration of stylets of Tylenchs, Trichodorids and Dorylaims (Trichodorid is Paratrichodorus hispanus from F. Roca and M. Arias [Nematol. Medit. 14:181-185]); 4.) video: Bursaphelenchus xylophilus, the pinewood nematode, feeding on mycelium of the fungus Gliocladium virens (real-time). 11.) Life Cycle. Illustrated are eggs (single, in egg masses and in a cyst, undifferentiated and fully differentiated); hatching juveniles (ectoparasitic and endoparasitic); maturing individuals; and adults (females and tail sections of males showing spicules). Build-ins: 1.) root-knot juvenile hatching from egg (400X in real time); 2.) reniform juvenile hatching from egg (1000X in real time); 3.) nematode life cycle durations. Note: The second stage juvenile (J2) is the infective stage for most plant parasitic nematodes. However, this is not the case with all plant parasites such as Rotylenchulus reniformis, where the preadult female is the infective stage. 12-14.) A Brief History of Plant Nematology. Notable background elements are Ebers Papyrus and a pinworm (Enterobius vermicularis) specimen from picturesofparasites.com; Build-ins: 1.) symptoms of nematode infestation on infested grain heads; seed (dark); second stage juveniles emerging from grain;   3 and juveniles (bottom) in anhydrobiotic state ( from M. McClure); 2.) verbatim text from Needham’s writing on the subject. Slides 13 & 14 are self-explanatory. 15.) A Phenetic Grouping of Nematodes. Build-in: Scutellonema brachyurum, the original classification of nematodes was based upon the presence or absence of phasmids (shown stained in the photograph). 16.) A Phylogenetic Grouping of Nematodes. Characteristics of Adenophorea and Secernentea. Location of the dorsal esophageal gland orifice (DEGO) in Tylenchina and Aphelenchina. Build-ins: the phylogenetic grouping of nematodes as presented in De Ley, P. A quick tour of nematode diversity and the backbone of nematode phylogeny (January 25, 2006), WormBook, ed. The C. elegans Research Community, WormBook, doi/10.1895/wormbook.1.41.1, http://www.wormbook.org. Another excellent website for consultation is http://insects.tamu.edu/research/collection/hallan/Nematoda/Family/0NematodaIn dex0.htm. 17.) Identification. Importance of the esophagus (referred to by some as the oesophagus or simply, pharynx) in the identification of nematodes; Build-ins: 1.) criconematoid esophagi; 2.) humor; 3.) parts of the esophagus; 4.) cross-section through Tylenchid nematode in the area of the median bulb showing the esophageal lumen; 5.) animation of the median bulb pump (P.M. Sforza and J.D. Eisenback). 18.) Morphology. The illustrations of male and female nematodes are not indicative of any particular genus. They are “hybrids” intended to provide students with knowledge of the basic external morphological features common on most plant parasites.  Note: DeMan’s values, employed in the identification of genera and species, are based on measurements of specific body regions of the nematode. Build-ins: 1.) additional DeMan values; 2.) cuticle and lateral field; 2.) head region (en face); 3.) types of sensilla.   19.) Internal Body Systems. Build-ins: 1.) types of reproduction by plant parasitic nematodes; 2 & 3.) monodelphic and didelphic ovaries; 4.) terms used to describe the arrangement of the uteri in nematodes; 5.) modified from illustration for C. elegans showing uterine and vulvular muscles. 20.) Position of the Vulva. Variation in the location of the vulva in plant parasitic nematode females. 21.) Reproductive System. Top right: the male- spicules, bursa types (leptoderan- bursa does not reach tail terminus, peloderan- bursa envelops the tail); Build-in 1: male tail (modified from illustration for C. elegans) showing the cloaca and gubernaculum; Bottom right: videos (C. elegans) showing mate-finding activity and copulation; Left: vulva of C. elegans and root-knot (RK) nematode; Build-in 2: egg development (C. elegans); eggs (stained red) in root tissue (lesion nematode); and hatching eggs (orange-unknown nematode (David Spears), green- Heterodera schachtii).   4 22.) Nervous System. Top right: modified from illustration for C. elegans sensory structures of male tail: B= bursa, R= bursal ray neurons, to NR= to nerve ring; Bottom right: Contracaecum rudolphii: S= sensillum; Bottom center: Steinernema riobravis; Bottom left: Xiphinema americanum: CS= cephalic sensillium (black arrows indicate amphid openings); Top left: NR= nerve ring; Top center: C. elegans male tail; Build-ins: 1.) (top) anterior of Laxus oneistus (A=amphid opening); (bottom) phasmid opening of Scutellonema brachyurum (hematoxylin- stained); 2.) head regions of (right to left) Rotylenchus sp.; Dolichodorus sp. and Neopsilenchus sp. (from K.B. Nguyen); 3.) A= amphid and illustration of the complexity of this sensory organ. 23.) Digestive System. Right center: anterior of a second stage juvenile of Heterodera glycines in ‘Lee’ soybean root (B.Y. Endo); Build-ins: 1.) anterior of nematode showing the stylet orifice; 2.) illustration of stylet musculature and connection with the esophageal lumen (green shows connection of the stylet with the esophageal lumen); 3.) anterior of Hoplolaimus galeatus; 4.) further along the esophagus (H. galeatus); 5.) illustration of the anterior of a nematode to the junction between the esophagus and the intestine; 6.) C= cardium of Tylenchorhynchus claytoni (BBE = basal bulb of esophagus, INT= intestine); 7.) DS= digestive system, dots trace the beginning to the end of the digestive system. 24.) Excretory/Secretory System. Top left: illustration (modified) of Plectus sp.; Top right: the excretory pore of C. elegans; Build-in: location of the excretory pore (exc. pore) and excretory gland (gland) on the illustration. 25.) Muscular System. Elements of the muscular system (red lettering) in mid (A) and anterior (B) portions of the nematode body. Modified from illustrations in The Atlas of C. elegans Anatomy (Altun, Z.F., R. Lints and D.H. Hall, 2002-2006). NOTE: The website www.wormatlas.org has a wealth of excellent information that anyone interested in nematodes of any kind would benefit from reviewing. Build- ins: 1.) reflexed ovary shown in cross-section in figure A; 2.) functions of the hypodermis. 26.) Nematode Habitats. Ecto- and endoparasitic nematodes. Top left: lesion and sting (grayscale); Right: juveniles (red), males (green) and females (dark blue) of RK (root-knot), CN= cyst nematode. Bottom illustration modified from: Hesling, J.J. and H.R. Wallace, 1961. Observations on the biology of chrysanthemum eelworm Aphelenchoides ritzemabosi (Schwartz) Steiner in florists chrysanthemum. I. Spread of eelworm infestation. Annals of Applied Biology 49:195-209. 27.) Parasitized Roots. Top left: white females of soybean cyst nematode (SCN) on soybean (www.entm.purdue.edu); Top right: cyst juvenile hatching from egg (ucdnema.ucdavis.edu) and lesion nematode female; Bottom right: ring nematodes feeding on alfalfa roots; Bottom center: Longidorus africanus feeding on root tip (www.faculty.ucr.edu); Bottom left: sugarcane root systems with and without nematodes (nematode sizes exaggerated for emphasis); magnifying glass inset shows swollen root-knot and vermiform spiral nematode females near root   5 section. Build-ins: 1.) stained SCN juveniles in soybean root tissue (www.extension.missouri.edu); 2.) above-ground symptoms of damage on horticultural crops: A & B.) boxwood nursery field and plant, respectively (Alexandria, LA) infested with root-knot nematode; C.) peach trees declining due to dagger nematode (Clinton, LA); D.) declining golf turf due to lance and sting nematodes (Bastrop, LA); 3.) above-ground symptoms of damage on agronomic crops; A-C.) (LA) A.) Meloidogyne incognita infested corn field (left row treated with Telone and right row not treated); B.) Rotylenchulus reniformis infested cotton soil (foreground not treated, background treated with Telone); C.) cotton field infested with M. incognita and R. reniformis; D.) soybean field infested with Heterodera glycines (www.entm.purdue.edu). 28.) Symptoms of Damage from Foliar (Above Ground) Nematodes. Rice (Crowley, LA), anemone (www.ppdl.purdue.edu), phlox (plant- disease.ippc.orst.edu), wheat, alfalfa (www.agf.gov.bc.ca), coconut (nematology.ifas.ufl.edu), pine (www.oznet.ksu.edu); Build-ins: 1.) tulip (www.eppo.org); 2.) self-explanatory; 3.) a point to ponder! 29.) Estimate of Yield Losses Caused by Plant Parasitic Nematodes. Loss estimates range from a low of 6.3 percent for barley (left, life-sustaining crops) to a high of 20.6% for tomato (right, economically important crops). Globally, the value of these losses is estimated to exceed $77 billion U.S. dollars. 30.) Nematode Movement and Dissemination. Build-outs: 1.) crawling C. elegans (www.abac.edu); 2.) movement pattern, modified from Brusca, R.C. & J.G. Brusca. 1990. Invertebrates; 3.) humor, however an excellent reference is:   Robinson, A.F., et al. 2005. Vertical distribution of Rotylenchulus reniformis in cotton fields. Journal of Nematology 37 (3): 265-271. Photographs: propagative stock (blog.agriculture.ph), tire (www.istockphoto.com), seed debris. Build-in: cartoon depicting the spread of nematodes such as is known for the potato cyst nematode, Globodera rostochiensis, via bird droppings. See also the work of Poinar and Yanoviak summarized on slide 94. 31.) Nematode Sampling Methodology. Modified from Zuckerman, Mai & Rhode. Build-in: a simple, but effective, message for producers (left image modified from one by G.L. Tylka). 32.) Nematode Extraction Techniques. Techniques (left top and bottom) illustrated include: the Baermann method (using funnels outside [usually for soil] or inside of a mist chamber [usually for root material], or a modification of the Baermann technique employing hardware cloth “sandwiched” between layers of PVC pipe [commonly 15-20 cm. in diameter] used for extraction from larger volumes of soil; and the semi-automatic elutriator (right top and bottom). Build-in: technician using the sugar-flotation centrifugation extraction technique. 33-36.) Nematode Population Dynamics. Information on slide 36 is modified from: Norton, D.C., 1978. Pp. 59-79 In, Ecology of Plant-Parasitic Nematodes. John Wiley & Sons, New York. Note: In an agricultural environment, the number   6 of genera comprising a community is usually, at most, 6-8. However, in a natural community the number of genera is frequently 30-60. 37.) Nematode Action, Damage and Economic Thresholds. Photographs: (left to right) cyst stage of Heterodera glycines, circular patch of stunted plants (soybean) “typical” of nematode injury, tomato roots galled by root-knot nematode and reniform female on root (cotton). Build-in: Nematode threshold information from other states. Terms: ET- defined on slide 37; DT (damage threshold)- the nematode level at which (relative to a nematode-free comparison) significant damage can be expected; AT (action threshold)- the nematode level at which some type of management tactic should be initiated. The table at the bottom provides current threshold (ET, DT, or AT) recommendations from the states listed and was supplied by: AR (T. Kirkpatrick), DE (R. Mulrooney), GA (R. Kemerait), IL (G. Noel & J. Bond), IA (G.L. Tylka), MS (G. Lawrence), SC (J. Mueller), TN (P. Donald & M. Newman) and VA (P. Phipps). 38.) Nematode Management Tactics. Top right: no-till cropping system (www.prebleswcd.com). 39.) Nematicides. Methyl bromide (entwew.clemson.edu), Temik (www.bayercropscience.cl), Furadan (www.sonti.cn). Build-ins: 1.) “hole” in the ozone layer of the atmosphere over Antarctica caused by human-produced compounds that release chlorine and bromine gases (www.NASA.gov); 2.) information about non-fumigant nematicides. Note: As of 11/2009, discontinued fumigants include: Meth-O-Gas, Brom-O-Gas, Terr-O-Gas and Vorlex. Discontinued Non-fumigants include Dasnit and Nemacur. Also note that nematacides formulated as seed treatments include Avicta Complete Cotton and Avicta Complete Corn (both produced by Syngenta) and AERIS Seed-Applied Insecticide/Nematicide (produced by Bayer Cropscience). 40.) New Tactics for Nematode Management. Photographs: (left to right) applying a low-dose nematicide as an at-planting, in-furrow spray; satellite (www.fcc.gov) and GPS technology in agriculture, nematode-trapping fungus (Arthrobotrys sp.). 41.) Reduced Rate Nematicide, an Example. (from current research in the nematology program of the LSU AgCenter with an experimental colloid). Build-ins: 1.) illustration of the 12 crops tested in trials in Louisiana; 2.) the greatest and most consistent yield response has been with cotton (3-acre field trials); 3.) self- explanatory; 4.) methods of application evaluated with this product (in all trials, a rate of 10 GPA of a 1% solution was employed, “transplant dip” treatments were for 8 seconds in a 1% solution.). 42.) Site Specific Farming, an Example. The use of GPS technology to document the exact location of a specific agricultural field ( from Google Earth). Build-in: a 100-acre cotton field in north Louisiana where the soil is co-infested with high levels of root-knot (Meloidogyne incognita) and reniform (Rotylenchulus reniformis) nematodes.   7 43.) Site Specific Farming 2. Top left: photograph and video, Build-in 1.) of a Veris 3100 soil electrical conductivity mapping system; Bottom left: diagram of the Veris 3100 instrument and explanation (right) of how it is used to determine soil electrical conductivity (EC). Other Build-ins: 2.) field map produced following delineation and mapping of EC values; 3.) establishment of verification strips; 4.) indicators of areas of the field that responded and failed to respond to treatment with a nematicide (Telone) in year 1. 44.) Site Specific Farming 3. A management zone map indicating areas of the field that should and should not be treated with a nematicide in year 2. Build-in: fumigant application implement. 45.) Site Specific Farming 4. The bottom line. 46.) Site Specific Farming 5. Software and hardware available to agricultural producers. 47.) Nematode Parasites: Pasteuria penetrans. Build out: information about P. penetrans. Life cycle (modified from that at www.pasteuriabio.com), electron micrographs (respectively, grayscale and colored electron micrographs from www.rothamsted.ac.uk by B. Kerry & K. Davies), P. penetrans endospore; Build- ins: 1.) (left) a low magnification photograph of a female sting nematode, (right) the anterior portion of a sting nematode female; 2.) colorized sting nematode and attached endospores (orange) of P. penetrans; 3.) information about other species of Pasteuria and the nematodes that they parasitize. 48.) Nematode Parasites: Fungi. Top left: Electron micrograph of a nematode trapped by Arthrobotrys sp.; Top right: trapping loops of Dactylaria brochopaga (www.iwf.de); Bottom: (left and right) RK (root- knot) eggs parasitized by fungi; Center: J4 of SCN (soybean cyst nematode) parasitized by ARF fungus. 49.) Expanded Phenetic Grouping of Nematoda. (Mai & Lyon, 1975). DEGO (dorsal esophageal gland orifice). Top right: (center) male of Tylenchorhynchus martini, (left) female of Gracilacus sp., (right) female of Paratylenchus sp.; Bottom right: female of Hemicriconemoides sp.; Left: (top to bottom, respectively) females of Helicotylenchus sp., Hoplolaimus sp. and Pratylenchus sp. 50.) Important Genera of Tylenchida. Self-explanatory. 51.) Evolution of Parasitism in Secernentea. Photos and credits (except top left [H. galeatus infecting grass roots]) identified earlier. 52.) Illustration of Modes of Parasitism. Modified from the artistry of R.P. Esser. Self-explanatory. 53-67.) Key to Genera of Plant Parasitic Nematodes. Some images included in this section were initially scanned at high resolution from the Pictorial Key to Genera of Plant Parasitic Nematodes by W.F. Mai and H. H. Lyon (see Acknowledgements). Where quality was lacking (to the eye of the first author),   8 original literature was obtained, images scanned and used with the “layers” and “image adjustments” functions of Photoshop CS3 to produce the modified images used in this section of the presentation. Note: Pop-up images by couplets serve EITHER to clarify a character description OR to illustrate a genus (red line connecting photograph or illustration to genus name). 68.) Comparison of Common Nematode Genera. Where there is significant variation among species in a genus, as for example the cyst life stage of Heterodera species, an “average” size is depicted. Also, aside from the plant parasitic nematodes, a free-living nematode (Rhabditis spp.) is included in the lower left section of the circle. 69.) Individual Nematode Genera of Greatest Economic Importance or Potential. Self-explanatory. Photographs: Top right: anhydrobiotic juvenile of Rotylenchulus reniformis; Center: molting juvenile of sting nematode, egg of R. reniformis; Bottom right: tail of male of Bursaphelenchus xylophilus; Bottom center: anterior of lance nematode female and female lesion nematode; Bottom left: anterior of female of Hoplolaimus galeatus; Top left: juvenile of root-knot nematode. 70.) Reniform Nematode. Photographs: Top: anhydrobotic juvenile, esophagus of juvenile; Middle row: (left to right) female on root (LM= light micrograph), female on root (EM= electron micrograph), infective fourth-stage juvenile on root, male; Bottom row: (left to right) females on root, soybean and cotton fields infested with R. reniformis, egg mass; Build-ins: 1.) stained and non-stained egg masses; 2.) host range; 3.) video. 71.) Soybean Cyst Nematode. Photographs: A.) a soybean field infested with the cyst nematode; B.) “yellow females” on soybean roots; C.) cyst with internal eggs visible; D.) “swollen” stages in the development of a cyst (white to brown); E.) soybean root tissue containing stained juveniles; F.) juvenile; G.) individual sperm cell of male; H.) second stage juvenile hatching from egg. Build-ins: 1.) cartoon showing the development of adults and cysts (modified, original source unknown); 2.) (left) female and male, (right) egg-filled cyst; 3.) females of the nematode compared with the size of a nodule on soybean; 4.) video (still photo comparing sizes of cyst females and nodules on roots from G. L. Tylka); 5.) egg-filled cysts of Heterodera glycines (100X). 72.) Root-Knot Nematode. Photographs: A.) a swollen endoparasitic female and external egg mass (both stained) in galled root tissue; B.) root tissue containing stained juveniles; C.) progressive (left to right) life stages (except egg) of the nematode; D.) galled tomato roots; E.) plants employed in the host differential assay (for the identification of “common” species and races…see slide 73); F.) galled carrot roots. Build-ins: 1.) (left) female dissected from fresh cucumber tissue, (right) female and egg mass from Chenopodium (E.C. Bernard); 2.) root- knot (M. incognita) infested field of soybeans near Alexandria, LA and galled root system; 3.) video.   9 73.) Root-Knot Host Differential Assay. This assay was developed by J. N. Sasser in 1954 and has been of immense value to the science of nematology. A plus (+) value indicates a susceptible host and a minus (-) value indicates a resistant host. Build-in: in addition to the host differential assay, perineal pattern morphology of root knot females (top center) is employed to distinguish between Meloidogyne hapla (Mh), M. javanica (Mj), M. incognita (Mi) and M. arenaria (Ma). In recent years, the use of esterase phenotypes (bottom center) is also employed as a further method of species confirmation. 74.) Lesion Nematode. Build-out: lesion nematode feeding in root tissue; Upper left: lesion nematode model (available from Mactode Publications); Lower right: female; Build-in: self-explanatory. 75.) Sting Nematode. Self explanatory. Lower left: sting nematode damage on strawberry; Build-in: self-explanatory. 76.) Pine Wilt Disease 1. Build-outs: Pine wilt symptoms on individual trees: 1- Louisiana, 1981; 2- Portugal, 1995 collecting pine wood samples near Setubal, PT (observations and collections made by E.C. McGawley while on a Fulbright sabbatical in Portugal first introduced agriculture and forestry personnel to this disease and made them aware of the likely presence of Bursaphelenchus xylophilus in the country); 3- Japan, 2008; 4- Pine wilt symptoms in a pine forest in Japan; Photographs: Top row: left- M. alternatus (L.D. Dwinell), cerambycid beetle on pine needles and log showing signs of infestation with blue-stain fungi (www.forestryimages.org) and cross section of M. caroliniensis trachea packed with juveniles of B. xylophilus; middle- Japanese black pines that are very susceptible to B. xylophilus; right- pine pallets, a likely vehicle for dissemination of the nematode; Bottom row: left- pine logs showing discoloration indicative of infestation with blue-stain fungi; middle- tail of male of B. xylophilus with characteristic “rose-thorn” shaped spicule (L.D. Dwinell); right- female of B. xylophilus (www.metla.fi). Pine wilt disease cycle in center of frame is modified from www.forestresearch.gov.uk. 77.) Pine Wilt Disease 2. Photographs: Top left: cultures of G. virens infested with B. xylophilus showing reduced growth and lack of sporulation (left) and similarly aged cultures sporulating in the absence of the nematode (right); the frame behind this shows the development of nematode-infested cultures over 12 days; Top right: culture of G. virens with characteristic “bowling pin” shaped phialides; Bottom left: B. xylophilus (respectively) male tail (low and high magnifications, respectively), juveniles of the nematode feeding on mycelium of G. virens, esophagus and vulva of female and line drawings of adults of the nematode; Bottom right: slash and loblolly pine seedlings used in inoculation studies conducted at LSU. 78.) Lance Nematode. Self explanatory. 79-80.) Nematode Disease Complexes. A good reference on this subject is: Sikora, R.A. and W.W. Carter, 1987. Nematode Interactions with Fungal and   10