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Los nematodos parásitos de plantas causan severos daños a los cultivos, con pérdidas económicas muy importantes y la calidad y cantidad de los productos cosechables se reducen significativamente. Muchos países de América Latina no cuentan con suficientes y bien preparados Nematologos, que estudien los nematodos parásitos de plantas en las diversas áreas geográficas, donde se cultivan hortalizas, frutales, pastos forrajeros, forestales etc. por lo que los agricultores y la industria, tienen severas perdidas económicas, sumándose a estas se suma, el costo de los productos químicos que se aplican, lo que reduce el beneficio para los agricultores. Esta situación es muy delicada en América latina, por la carencia de profesionistas Nematologos bien preparados para la enseñanza, la investigación, y extensión agrícola. En esta publicación se presenta la información que cualquier curso profesional debe tener, incluyendo la Nematologia, como es el contar con un Programa Analico teórico y práctico, donde los estudiantes se informan del contenido del curso, forma de evaluación y la literatura electrónica e impresa, donde los estudiantes pueden ampliar la información que se da en cada tema y convertirse en un curso básico de Fitopatología y muy importante en su carretera profesional.

Summary A new species of stubby root nematode, Trichodorus lownsberyi sp. n., collected from soil around Buxus sempervirens at Montecillo Campus, Colegio de Postgraduados, Mexico, is described and illustrated. Trichodorus lownsberyi sp. n. is characterised by the abundant males with a characteristic spicule shape, the narrower part about mid-blade having visible bristles in most specimens, and the presence and position of the three ventromedian cervical papillae, which are all anterior to the secretory-excretory pore. Females possess a rhomboid-shaped vagina and oval to rounded triangular vaginal sclerotised pieces with a pore-like vulva. The phylogenetic relationships of T. lownsberyi sp. n. with related species were constructed using the ITS2 rRNA and the D2-D3 expansion segments of 28S rRNA gene sequences. Trichodorus lownsberyi sp. n. was a sister species to T. viruliferus in the phylogenetic trees. A Mexican population of Nanidorus minor from a peach orchard is also described and illustrated. The new needle nematode, Longidorus quercus sp. n., was recovered from soil around roots of oak, Quercus crassipes, from Cerro Jusda ‘El Diablo’ in Mexico State. Longidorus quercus sp. n. females are characterised by the C-shaped posterior end of the body after fixation, L = 4.9 (3.9-5.6) mm, a = 71 (60.8-93.2), lip region rounded, sometimes slightly flattened, marked by depression, odontostylet 170 (144-206) μm long, hemispherical to bluntly conoid tail and no males. The new species was characterised using the D2-D3 of 28S rRNA and COI gene sequences. The phylogenetic relationships of L. quercus sp. n. with other Longidorus species were reconstructed using the D2-D3 of 28S rRNA gene sequences.

The cystoid sedentary nematodes of the Heteroderidae include more than 30 recognised species belonging to from nine to 11 genera, depending on the opinion of the authority. In the present study, we collected nematode populations of species belonging to some of these genera, as well as other cyst-forming species from different locations in the USA, Vietnam, Germany and Russia. The populations of cystoid nematodes represent seven valid species, Atalodera carolynae, Cryphodera sinensis, Meloidodera astonei, M. floridensis, M. mexicana, M. sikhotealiniensis, Rhizonemella sequoiae, two unidentified species of Atalodera, six unidentified species of Cryphodera, and three putative new species of Rhizonemella. We also obtained samples of cyst-forming nematodes that include an unidentified species of Betulodera from California, and Heterodera guangdongensis from Vietnam. A population of Rotylenchulus sp. from Arizona, intercepted in Florida, and a population of an unidentified species of Verutus from Germany were also added to this study. All of these populations were characterised using sequences of the D2-D3 of 28S rRNA, ITS rRNA or mitochondrial COI genes. A total of 89 new sequences were obtained from these analyses. Phylogenetic relationships within the family Heteroderidae were reconstructed based on the D2-D3 of 28S rRNA, ITS rRNA and mitochondrial COI gene sequences. Results revealed that the subfamily Ataloderinae was paraphyletic. Ekphymatodera thomasoni, a non-cyst-forming species, clustered with the cyst-forming nematodes. Representatives of the subfamily Verutinae formed clades within Heteroderidae. The genus Meloidodera was non-monophyletic and distributed within two clades: i) M. sikhotealiniensis and Cryphodera spp. from Asia and Europe; and ii) M. astonei, M. floridensis and M. mexicana from North America. Based on comparative molecular analysis Meloidodera alni syn. n. is proposed as a junior synonym of M. sikhotealiniensis. Problems of taxonomy and phylogeography of cystoid nematodes are also discussed.

Plant parasitic nematodes are recognized as one of the most important limiting factor in crop production worldwide and Mexico is not an exception. Economic losses caused by nematodes are influenced by growing system type (multicropping, monocropping, crop rotation in open-field and greenhouse conditions, among others), species involved and their population densities. In Mexico, damages and losses are caused mainly by lesion nematodes (Pratylenchus spp. and Radopholus similis), the stem and bulb nematode (Ditylenchus dipsaci), root knot nematodes (Meloidogyne spp.), false root knot nematode (Nacobbus aberrans), cyst nematodes (Globodera spp. and Punctodera chalcoensis), the citrus nematode (Tylenchulus semipenetrans), virus transmitting nematodes (Xiphinema spp.), foliar nematode species (Aphelenchoides spp.) and red ring nematode (Bursaphelenchus cocophilus). Some of these nematodes have been observed in commercial plantations, crop fields and greenhouses where mono-cropping is more common and crop rotation is not practiced.

A new species of cyst nematode, Cactodera torreyanae sp. n., parasitising romerito plants, Suaeda torreyana (Chenopodiaceae), found in highly saline soils in Texcoco, Mexico, is described. The new species is morphologically and molecularly related to C. weissi, from which it differs in smaller fenestral diam., longer body and shorter tail lengths of second-stage juveniles (J2) and to C. rosae, from which it differs in smaller cyst size, longer body length of J2 and the presence of a smooth eggshell surface. Phylogenetic relationships within populations and species of the Punctoderinae and Cactodera are given based on the analysis of the D2-D3 expansion segments of 28S rRNA and the ITS rRNA gene sequences.

Five new species of the genus Tripylella are described, two from México, one from Fátima, Portugal, one from Quito, Ecuador, and one from California, USA. Tripylella mexicana sp. n. is characterized by its short body (average 0.74 mm), short pharynx (average 161 μm), short tail (average 117 μm), presence of an excretory pore and small setae distributed sparsely along the body, the presence of body pores, the posterior position of the subventral teeth in relation to the small dorsal tooth with all teeth in contiguous stomal chambers, the finely-striated cuticle with many anastomoses, the non-protruding vulval lips, and the presence of sclerotized pieces in the vulval region. Tripylella muscusi sp. n. is characterized by its body length (average 0.94 mm), pharynx length (average 201 μm), tail length (average 140 μm), the anterior position of the subventral teeth in relation to the small dorsal tooth in a single stomal chamber, the presence of an excretory pore, the presence of body pores and sparse somatic setae, the finely-striated cuticle with sparse anastomoses, protruding vulval lips and sclerotized oval-shaped pieces present in the vulval region. Tripylella quitoensis sp. n. is characterized by the short body length (average 0.72 mm), the short outer labial setae, the short pharynx (average 175 μm), the location of the anterior subventral teeth and posterior dorsal tooth in the same stomal chamber, the short tail (average 98 μm), the apparent absence of an excretory pore, presence of body pores, presence of somatic setae, a finely-striated cuticle, non-protruding vulval lips, and very small oval sclerotized pieces in the vulva. Tripylella fatimaensis sp. n. is characterized by the short body, (average 0.74 mm) long, by the length of the pharynx (average 180 μm), the length of the tail (average 110 μm) and in the length of its reduced diameter portion, 45-58 μm, the presence of an excretory pore, body pores and three pairs of caudal setae (one pair each latero-ventral, latero-dorsal and ventral). Tripylella dentata sp. n. is characterized, and differs from all the species of the genus, by the presence of two adjacent stomal chambers, with two large teeth, one dorsal and one ventral, in the posterior stomal chamber and two subventral teeth in the anterior smaller chamber, short body (average 0.85 mm), pharynx length (average 209 μm), tail length (average 115 μm), the apparent absence of an excretory pore, the presence of two cervical setae in a lateral position, and by the presence of conspicuous pores along the body.

Abstract Some 134 ITS rRNA gene sequences for circumfenestrate cyst nematodes and two sequences for non-cyst nematodes of the family Heteroderidae, of which 46 were newly obtained, were analysed by phylogenetic and phylogeographic methods. Sequence and phylogenetic analysis combined with known morphological, biological and geographical data allowed the identification, amongst samples original to this study, of several belonging to known valid species as well as others that might be new species. The phylogenetic analysis revealed six major clades for circumfenestrate cyst nematodes: i) Globodera from South and North America; ii) Globodera from Europe, Asia, Africa and Oceania; iii) Paradolichodera; iv) Punctodera; v) Cactodera; and vi) Betulodera. Monophylies of Punctodera, Cactodera and Betulodera were highly supported. The Betulodera clade occupied a basal position on all trees. Phylogeographic analysis suggested a North American origin of Punctoderinae with possible further long distance dispersal to South America, Africa and other regions. Molecular data supported synonymisation of G. achilleae with G. millefolii and of G. hypolysi with G. artemisiae. PCR-RFLP diagnostic profiles for some Globodera and Cactodera species are given. Problems of diagnostics for Globodera species using PCR with specific primers are discussed.

Abstract Population densities, population fluctuations, yield loss and disease incidence caused by Nacobbus aberrans on tomato (Lycopersicon esculentum) were studied, using an epidemiological approach, in a field experiment that included three different control regimes: an integrated control (IC) scheme, which included fertilisation, nematicide (ethoprop) and chicken manure; a technical control (TC) scheme, based on the best local practices of fertilisation and use of carbofuran for nematode control; and a check treatment (AC), with no application of fertilisers or nematicide. At least three generations of N. aberrans occurred through the cropping season and the numbers of galls/plant and females/g of root through the crop season were used to define the area under a disease progress curve (AUDPC). The variables b−1 (Weibull's apparent infection rate), AUDPC and Yf (final disease incidence) indicated less crop damage under the IC scheme than under the other two schemes (TC and AC). The IC scheme resulted in increased plant height (41-49%), foliage dry weight (37-53%) and stem diameter (31-41%) compared with the TC and AC schemes. Tomato yields in IC surpassed those from TC and AC by 34 and 83%, respectively, while TC exceeded AC by 73%. The yield loss attributed to N. aberrans was 12, 29 and 83% in IC, TC and AC, respectively. The IC scheme improved commercial production by 20 and 81% in comparison to the TC and AC schemes. This was largely due to effective control of the initial inoculum density, which affects the first generation of the nematode population; control of this generation is essential for avoidance of yield loss. The first generation is completed during the period 0-60 dat (days after transplanting), i.e., during the critical stages of flowering, fruit initiation and fruit set (40, 50 and 60 dat). Data on plant performance taken every 10 days were used to derive a multiple point model for calculation of production loss.

Three new species of Trischistoma and two new species of Tripylina (Trischistomatidae) are described. Trischistoma ripariana n. sp. was collected in the surface organic material and upper rhizosphere soil on a stream bank in Oakville, California, USA. It is characterized by a short, thin body, the vulva at 79-83%, a small index c (17-29) and a short tail, 34-57 µm. Trischistoma corticulensis n. sp. was found in moss on tree bark in a tropical forest at the La Mancha Ecological Institute, Veracruz State, Mexico. The vulva is at 67-73% and the tail is elongate conoid (51-84 µm). Trischistoma helicoformis n. sp. was collected on lichen growing on tree bark near the Carretera Interamericana in Costa Rica. It is characterized by its spiral shape after fixation, the tail length (76-101 µm), a very small index c (10-14.5) and very small sclerotised pieces around the vagina. Tripylina rorkabanarum n. sp. was collected from moss on tree bark in a tropical forest at the La Mancha Ecological Institute. It is characterized by the presence of two cervical setae, the position of the subventral teeth posterior to the dorsal tooth, the absence of sclerotized pieces around the vagina and the distance of the dorsal tooth from the anterior, 10-15 μm. Tripylina iandrassyi n. sp. was collected from soil around a banana tree at the La Mancha Ecological Institute. It is characterized by the presence of a post-uterine sac, well-developed buccal lips, subventral teeth located posterior to the dorsal tooth, one cervical seta in females and two in males, and by spicules not completely surrounded by a muscular sheath.

Se describen las alteraciones anatómicas causadas por C. galinsogae en las raíces de cebada (Hordeum vulgare) cv. Esmeralda, recolectadas a 10, 20 y 40 d post-emergencia de las plantas, en Singuilucan, Hidalgo. Se trata de un patógeno descrito recientemente, del cual se desconocen las lesiones que induce en la hospedera.El examen histológico mostró a los 10 d juveniles (J2, J3) en el tejido cortical, observándose rompimiento de las células aledañas. A los 20 d, los juveniles (J3, J4) se encontraron próximos al cilindro vascular. Además se observó la inducción de primordios laterales cerca del nematodo. Los sitios de alimentación, pequeños e irregulares, abarcaron menos de 50% del cilindro vascular y el tejido cortical, con disolución de paredes celulares internas y engrosamiento de las celulares externas, y con desorganización, desplazamiento y rompimiento del xilema y floema. A 40 d, en los cortes transversales, los sincicios tuvieron mayor tamaño, abarcando de 50 a 60% del cilindro vascular. A nivel celular los cambios fueron similares a los observados a los 20 d, además de encontrarse abundante almidón. Las hembras maduras se observaron en la corteza rodeadas por una capa de felógeno y los machos aparecieron doblados en el mismo tejido.

Nematodo agallador, Meloidogyne incognita, Meloidogyne arenaria, Meloidogyne javanica, Meloidogyne hapla

El pasado martes 17 de diciembre, 2013 en la Ciudadde Mexico, D. F., fallecio el Dr. Marcos Rafael Lamothey Argumedo, Curador de la Coleccion Nacional deHelmintos, Investigador del Instituto de Biologia, miembrodel Sistema Nacional de Investigadores y profesor deinnumerables generaciones de biologos en la UniversidadNacional Autonoma de Mexico (UNAM).