Showing papers in "Nematologica in 1973"
TL;DR: A scheme is presented that describes observed behaviour leading to feeding and provides a foundation for further behavioural studies, and includes locomotion, head movements and probing with the stylet.
Abstract: Filmed observations of eleven tylenchid species show the same basic pattern of behaviour leading to feeding. Simple sequences of behaviour initiated in response to stimuli lead to egg-hatching and host penetration. Searching behaviour, stimulated chemically by a host, includes locomotion, head movements and probing with the stylet; this is called widespread exploration. In local exploration, when a surface has been encountered, locomotion stops and the surface is examined by lip rubbing and stylet probing. If found favourable, the surface is penetrated by repeated stylet thrusting, during which the body and head are immobile and the lips are pressed against the surface. On a food-cell feeding follows. In the cutting cycle, penetration by stylet thrusting alternates with very localised exploration and a slit is cut (e.g., in eggshell or plant-cell wall) through which the nematode then passes. Stimuli that initiate exploration, penetration and feeding, probably include surface contour, texture, deformability and chemical nature all sensed through labial tactors, muscle proprioceptors and amphids. But whether or not a response is made depends on physiological state. On this basis a scheme is presented that describes observed behaviour leading to feeding and provides a foundation for further behavioural studies.
56 citations
Journal Article•
43 citations
TL;DR: The sperm output of the non-feeding, adult male is limited, possibly conserving reserves of energy for mate-finding and resources are also conserved when, during maturation of the spermatozoa, the discarded cytoplasm and organelles of the so-called 'residual bodies' are engulfed by cells of the testis wall.
Abstract: In both round (Heterodera s.g. Globodera Skarbilovich) and lemon-shaped (H. s.g. Heterodera Skarbilovich) species of cyst nematodes studied, the early stages of spermatogenesis were completed in the 4th-stage larva and no further cell divisions took place after the last moult. Only spermatids and spermatozoa were present in adult males; in old males the whole gonad was occupied by mature sperm. Evidently the sperm output of the non-feeding, adult male is limited, possibly conserving reserves of energy for mate-finding, Resources are also conserved when, during maturation of the spermatozoa, the discarded cytoplasm and organelles of the so-called 'residual bodies' are engulfed by cells of the testis wall. Heterodera sperm resemble other described nematode sperm in being aflagellate and amoeboid, in lacking a nuclear membrane during all stages except the spermatogonium and in having a fibrillar storage product in the spermatids which in H. rostochiensis disperses during the transition to sperm but in H. schachtii is retained. They differ from other nematode sperm in lacking the polarity, the secretory granules and the so-called 'membrane specialisations' found in one or other of the four main types of nematode sperm, and in possessing a layer of cortical microtubules lining the whole surface of the sperm, including the pseudopodia. In round-cyst nematodes the state of condensation of the sperm nucleus changes several times during spermiogenesis and insemination, the chromatin passing through a compact homogeneous, a finely stranded, another compact and finally a coarsely stranded phase. These changes have not been recorded in other nematode sperm. The sperm nucleus in lemon-shaped cyst nematodes does not pass through the finely stranded phase in the testis, a further difference distinguishing the two main groups of cyst nematodes.
41 citations
TL;DR: The ultrastructure of a bacterium-like organism found living intracellularly in tissues of two Heterodera spp.
Abstract: The ultrastructure of a bacterium-like organism found living intracellularly in tissues of two Heterodera spp., one a population of H. rostochiensis from Bolivia, S. America, and the other a population of H. goettingiana from Lincolnshire, England, is described. The organism was particularly abundant in the reproductive system but did not prevent the production of fertilised eggs. It closely resembles the so-called 'companion symbiont' found in leafhopper insects, both in general morphology and in having striated inclusion bodies.
30 citations
TL;DR: It was inferred that the feeding activity of the nematodes is maintained at a constant level over a wide range of bacterial concentrations, and the contention that C. briggsae requires dense suspensions of bacteria for the maintenance of cultures was supported.
Abstract: The rate of removal of the bacterium E. coli from aqueous suspensions by C. briggsae in feeding has been studied. The decrease in bacteria with time follows a negative exponential equation when bacterial multiplication was restricted and nematode growth was minimal. It was inferred that the feeding activity of the nematodes is maintained at a constant level over a wide range of bacterial concentrations. Other experiments supported the contention that C. briggsae requires dense suspensions of bacteria for the maintenance of cultures and gave estimates of the efficiency of conversion of bacterial protoplasm to worm protoplasm.
28 citations
TL;DR: Evidence is given of a temporary inhibition of hatching induced by the presence of aldicarb in concentrations greater than 1 ppm, and the ability to hatch is restored when cysts initially treated by a Aldicarb are removed to aldedicarb-free root diffusate.
Abstract: Aldicarb (TemikR, UC-21149 or 2-methyl-2-(methylthio) proprionaldehyde O-(mcthylcarbamoyl) oxime) partially controls Helerodera rostochiensis Woll (potato cyst eelworm) but its mode of action is not completely understood Its systematic properties are well-known but there is conflicting evidence concerning the direct effect upon unhatched eggs and larvae within cysts Evidence is given of a temporary inhibition of hatching induced by the presence of aldicarb in concentrations greater than 1 ppm The ability to hatch is restored when cysts initially treated by aldicarb are removed to aldicarb-free root diffusate and the potential hatch is not seriously impaired, whereas the potential hatch in root diffusate of cysts initially treated by a mixture of aldicarb and root diffusate is considerably reduced These effects tend to be greater at higher concentrations of aldicarb (5-20 ppm) and after longer periods of exposure (up to 12 weeks) The practical implications are discussed
27 citations
TL;DR: In old nematodes fine structure changes related to aging were observed in two layers, and the outer osmiophilic membrane became more defined and in a few cases separated from the external cortical layer.
Abstract: The cuticle of young, adult Caenorhabditis briggsae contains seven layers. In old nematodes fine structure changes related to aging were observed in two layers. The outer osmiophilic membrane became more defined and in a few cases separated from the external cortical layer. Also, an electron-dense material and electron-dense balls occurred within the fluid-filled layer. The possible significance of these observations is discussed.
26 citations
TL;DR: The feeding of Tylenchorhynchus dubius on epidermal cells and root hairs of seedling roots of Brassica rapa var.
Abstract: The feeding of Tylenchorhynchus dubius on epidermal cells and root hairs of seedling roots of Brassica rapa var. silvestris was studied and analysed with the aid of cine film. The cell wall was punctured by rapid and characteristically irregular stylet thrusts. During salivation salivary granules flowed continuously from the site of synthesis in front of the dorsal gland-cell nucleus, through the gland duct towards the gland reservoir. Inside the cell a clear zone developed around the stylet tip and cytoplasm then accumulated there. The median bulb muscles contracted spasmodically, but uncoordinatedly so that the metacorporeal lumen was not dilated. At the onset of ingestion the forward flow of salivary granules through the duct was stopped by pump pulsations which soon became steady and very fast. Cytoplasm continued to accumulate around the clear zone in the food cell. Granular constituents of the cytoplasm were never seen to be drawn into the stylet. The accumulated cytoplasmic mass was never completely removed. After the nematode's departure this mass started to coagulate first. Cyclosis slowed down and finally stopped. Parasitized root hairs stopped growing. A comparison is made between the feeding of T. dubius and Trichodorus similis on the same host species.
25 citations
TL;DR: Water movement is established as the dominant primary event in osmoregulation and the results suggest a different path of permeation for those substrates with different affinity for the animals.
Abstract: Specific rate constants for the diffusion controlled permeation of Aphelenchus avenae by a wide variety of organic substances and the equilibrium constants for the process have been measured. In general, hydrophobic, nonpolar, organic soluble structures permeate the quickest and have the greatest affinity for the nematodes. In contrast, salts, hydrophilic, and polar substances are the slowest permeators and have the lowest affinity for the animals. The nematicide 1,3-dichloropropene in the fastest permeator (kin = 1.3 min-1, kout = .094 min-1) and glucose is one of the slowest (kin = 1.3 × 10-4 min-1, kout = 5 × 10-3 min-1). The small neutral polar molecules, water, acetone, and methanol are an exception to these findings. The rate in and out of these substances is unusually rapid. The results suggest a different path of permeation for those substrates. The water permeation rates are not affected over a wide range of osmotic pressure but the animals do decrease in size. The rate of shrinkage is slow at an osmotic pressure of 10 atm but approaches the rate of water permeation at 26 atmospheres. The results establish water movement as the dominant primary event in osmoregulation.
23 citations
TL;DR: Following penetration, larvae initially became oriented acropetally, parallel to the stele and could migrate up to 12 mm towards the growing tip, however, by 32 hr they were randomly oriented.
Abstract: Larvae of Meloidogyne incognita failed to penetrate root tissues 4 cm from the root tip and only a few penetrated 2 cm from the tip. Following penetration, larvae initially became oriented acropetally, parallel to the stele and could migrate up to 12 mm towards the growing tip. However, by 32 hr they were randomly oriented. The inoculation procedure utilized assures uniform, synchronous penetration of cotton roots by these nematodes.
23 citations
TL;DR: In roots of potato resistant to H. rostochiensis pathotype A, higher activities of both phenylalanine ammonia-lyase (PAL) and tyrosine ammonia (TAL) were found than in roots of susceptible potato, and the activity of these enzymes increased being greater in resistant plants.
Abstract: In roots of potato (Solanum tuberosurn X S. tuberosum subsp. andigena) resistant to H. rostochiensis pathotype A, higher activities of both phenylalanine ammonia-lyase (PAL) and tyrosine ammonia-lyase (TAL) were found than in roots of susceptible potato. After infection of roots with H. rostochiensis larvae, the activity of these enzymes increased being greater in resistant plants. Both trans-cinnamic acid and p-coumaric acid products of PAL and TAL activity, respectively, caused some resistant reaction to H. rosiochiensis after their introduction into potato plants. The possible role of the two de-aminases in potato resistance to H. rosiochiensis is discussed.
TL;DR: In this paper, the scanning electron microscope on spicule structure of eleven species of Heterodera has been used to confirm that spicules of H. rostochiensis contain a large nerve which tapered towards the tip of each spicle, where two dendritic elements were associated with the pores.
Abstract: Observations with the scanning electron microscope on spicule structure of eleven species of Heterodera confirmed that the spicule tips in species of H. (Heterodera) were basically bifid whereas those of H. (Globodera) had single points. In all the species two small pores were located close to the tip of each spicule. Sections through the spicules of H. rostochiensis observed with the transmission electron microscope showed that they contained a large nerve which tapered towards the spicule tip, where two dendritic elements were associated with the pores. The shape of the spicule blades, which have incurved, interlocking wings, ensures an enclosed, tubular structure through which sperm can he transferred when the spicules are protruded and inserted into the female reproductive tract. In mating, the spicules may have a sensory function.
TL;DR: A needle nematode, Longidorus euonymus n.
Abstract: A needle nematode, Longidorus euonymus n.sp. is described; it was frequently found with a dagger nematode Xiphinema vuittenezi Luc et al., 1964 in the rhizosphere of Spindle trees (Eunoymus europaeus L.) that were often infected with euonymus mosaic virus (EMV) in different localities of the Bratislava district. L. euonymus n. sp. is most similar to L. closelongatus Stoyanov, 1964 and L. cohni Heyns, 1969 but has a much shorter odontostyle than either of these and a relatively fatter body than L. cohni; it also resembles L. vineacola Sturhan & Weischer, 1964 but has a more offset lip region, shorter odontostyle and relatively longer female tail; it is generally larger than L. attenuatus Hooper, 1961 and L. elongatus (de Man, 1876) with a more offset lip region than L. elongatus and a wider and more bluntly rounded female tail than either of these species. Details are also given of juvenile stages. In transmission trials, juveniles and females of L. euonymus acquired EMV from mechanically inoculated cucumber-plants and transmitted it to healthy cucumber-plants but juveniles and females of X. vuittenezi failed to do so under the same conditions. L. euonymus was not necessarily responsible for the incidence of EMV on Spindle trees because the fungus Olpidium brassicae, that also transmits this virus, was present at most sites.
TL;DR: The genetic control of resistance and susceptibility of seven tomato cultivars was investigated against a single stock culture of Meloidogyne incognita and it was shown that the cultivars Nematex, Small Fry, and Cold Set each possess a single gene for resistance.
Abstract: The genetic control of resistance and susceptibility of seven tomato cultivars was investigated against a single stock culture of Meloidogyne incognita. Segregations obtained from the F 2 and backcross progenies derived from crosses Nematex X Chico III, Nematex X Enterprizer, Small Fry X Chesapeake, and Cold Set X IPB show that the cultivars Nematex, Small Fry, and Cold Set each possess a single gene for resistance. The resistance gene was dominant in cultivars Nematex and Small Fry and recessive in cultivar Cold Set. The three R-genes possessed by cultivars Nematex, Small Fry, and Cold Set are tentatively designated as LMiR 1 , LMiR 2 , and LMir 3 , respectively.
TL;DR: Comparison of type material of Trichodorus aerequalis Allen and T. sparsus Szczygiel, 1968 showed that these species can be distinguished by the spicules being setose in the latter and smooth in the former species, and by the shape of the male tail.
Abstract: Comparison of type material of Trichodorus aerequalis Allen, 1957 and of T. sparsus Szczygiel, 1968 showed that these species can be distinguished by the spicules being setose in the latter and smooth in the former species, and by the shape of the male tail. The difference in arrangement of the ventral cervical pores in the male, which is suggested by the original descriptions, is non-existent. No clear-cut differences were found between females. Variation in these two species appears to be greater than in other Trichodorus species. A population from Plymouth, South England, shows aberrant characters: smooth, almost straight spicules; females with only one pair of lateral cuticular pores. This population is considered to represent a separate species, here described as T. hooperi.
TL;DR: The relation between yield and average nematode density remains in accordance with eq.
Abstract: Usually the relation between relative yield of plants y and nematode density P is well described by the arbitrary equation (1) y = m + (1-m)zP-T for P T, and y = 1 for P T, (m = relative minimum yield, z a factor < 1, T = the tolerance limit and z-T = 1.05 to 1.1). Only an average value for the nematode density in a field (P(av)) can be determined by investigating a soil sample. According to eq. (1) the relation between y and P is not linear. Therefore the relation between P (av) and yield depends on the distribution of the nematodes in the field. If the expected yield is estimated with the help of eq. (1) assuming m to be 0 and substituting P (av) for P losses are overestimated for P (av) 2 T. The over-estimation is greater the more the distribution of the nematodes differs from a random one. The relation between yield and average nematode density remains in accordance with eq. (1) for P < 100 T, but the value of m is higher the more irregular the nematode distribution.
TL;DR: Evidence is presented that alanine, asparagine, cysteine, glutamate, glutamine, glycine, proline, serine and tryosine can be synthetized at adequate levels; they are called non-essential amino acids.
Abstract: Washed yeast ribosomes promote growth and reproduction of C. briggsae, even when supplemented to the basal medium at dosages too low to provide the organisms with sufficient amounts of essential amino acids. Hence, a re-investigation of the amino acid requirements of C. briggsae by single and multiple omission of amino acids from the basal medium revealed unambiguously that arginine, histidine, lysine, tryptophan, phenylalanine, methionine, threonine, leucine, isoleucine and valine are not synthetized at levels to permit reproduction; they are called essential amino acids. The requirement for arginine and isoleucine however appears to be less clear-cut. On the contrary, evidence is presented that alanine, asparagine, cysteine, glutamate, glutamine, glycine, proline, serine and tryosine can be synthetized at adequate levels; they are called non-essential amino acids. In addition it was shown that multiple omission of the non-essential amino acids is not deleterious. This is believed to be an important step towards the development of a minimum essential medium (MEM) for growth and reproduction of C. briggsae.
TL;DR: The histology of the permanent feeding site of Rotylenchulus reniformis was studied in roots of inoculated seedlings of upland cotton, tomato and mint and the most outstanding host reactions were hypertrophy of pericycle cells and a thickening of cell walls in the endodermis.
Abstract: The histology of the permanent feeding site of Rotylenchulus reniformis was studied in roots of inoculated seedlings of upland cotton, tomato and mint. The nematode fed in the stelar region and the most outstanding host reactions were hypertrophy of pericycle cells and a thickening of cell walls in the endodermis. Multinucleate giant cells were not observed in any of the hosts.
TL;DR: Survival of Pralylenchus penetrans and P. minyus was studied in columns of Fox loamy sand and Vineland silt loam under various physical conditions and suggested that the population of the former species was heterogeneous and that the latter species was homogeneous.
Abstract: Survival of Pralylenchus penetrans and P. minyus was studied in columns of Fox loamy sand and Vineland silt loam under various physical conditions. Survival of both species declined with time, with temperature as it increased above 2° C, and with increased soil moisture. Neither species survived sub-zero temperatures. Survival of adults and 4th stage larvae of both species was greater than that of 3rd and 2nd stage larvae. More P. penetrans survived in Fox loamy sand than in Vineland silt loam and in both soils P. minyus survived better than did P. penetrans. Results with P. penetrans and P. minyus suggested that the population of the former species was heterogeneous and that the population of the latter species was homogeneous. Both nematodes were classified as "freezing susceptible".
TL;DR: Results showed that tolerant, resistant and immune tomato cultivars contained more dry matter than did susceptible cultivars, and Phenolic content was found to be directly related to root-knot nematode resistance.
Abstract: A study was undertaken of the pre-infection factors in root-knot nematode resistant tomato cultivars. Roots of tolerant, resistant, immune and susceptible tomato cultivars were analysed for dry matter, nitrogen, phosphorus, potassium, phenolics and amino acids. Results of these analyses showed that tolerant, resistant and immune tomato cultivars contained more dry matter than did susceptible cultivars. Phosphorus content was greater in susceptible cultivars. Number and kinds of free and bound amino acids were the same in resistant and susceptible cultivars. Phenolic content was found to be directly related to root-knot nematode resistance, being highest in immune cultivars and species, followed by resistant, tolerant and susceptible cultivars.
TL;DR: From studies of plant parasitic nematodes by cinematography a motor scheme relevant to much of the behaviour of small nematode is proposed, which may also control stylet action, move sperms and eggs and be concerned in pharyngeal pumping in some rhabditids and tylenchids.
Abstract: From studies of plant parasitic nematodes, especially Aphelenchoides blastophthorus, by cinematography a motor scheme relevant to much of the behaviour of small nematodes is proposed. An anisometric cuticle, able to extend markedly in a longitudinal direction but only slightly around its circumference, surrounds visco-elastic organs which in turn enclose liquid gut contents. Longitudinal somatic muscles shorten locally and their consequent thickening creates radial forces which displace other organs, notably the gut and its contents. Waves of contraction and relaxation in dorsal and ventral muscles may be in or out of phase. When waves are in phase gut contents are moved, as in defaecation, or locomotion results as in criconematids. When the waves are out of phase undulatory propulsion is produced. Expansion of radial muscle and deformation of viscoelastic body organs within an anisometric cuticle, with or without translocation of liquid elements, may also control stylet action, move sperms and eggs and be concerned in pharyngeal pumping in some rhabditids and tylenchids.
TL;DR: Sixteen species of plant nematodes are reported, associated with plants in the states of Oaxaca, Nuevo Leon, Zacatecas, Sinaloa, Sonora, Coahuila and Campeche, Mexico.
Abstract: Sixteen species of plant nematodes are reported, associated with plants in the states of Oaxaca, Nuevo Leon, Zacatecas, Sinaloa, Sonora, Coahuila and Campeche, Mexico. Three species described as new are Tylenchorhynchus mexicanus, Quinisulcius obregonus and Helicotylenchus craigi.
TL;DR: Populations became established on cultures of algae, but penetration and feeding were limited by food-cell size, and odontostyle formation was evident at all but the pre-adult moult.
Abstract: The biology of a new species of Aporcelaimellus is described and illustrated. Populations became established on cultures of algae, but penetration and feeding were limited by food-cell size. Hatching occurred 230-250 hours after laying. Separation of membranes was evident at one pole of the egg prior to emergence. The first juvenile stage required 14-18 days for completion; the second stage, 16-23 days; the third stage 26-34 days, and the fourth stage, 25-39 days. Odontostyle replacement occurred during each moult, and odontostyle formation was evident at all but the pre-adult moult. Nematodes which had been feeding on the alga Haematococcus sp. defaecated solid material at the conclusion of each moult.
TL;DR: In pot tests, Xiphinema index reproduced on Vitis vinifera, Solanum tuberosum, S. dulcamara and Lycopersicon esculentum but not on Lolium perenne and Brassica oleracea, while feeding on the three latter species was predominantly at the root tip.
Abstract: In pot tests, Xiphinema index reproduced on Vitis vinifera, Solanum tuberosum, S. nigrum, S. dulcamara and Lycopersicon esculentum but not on Lolium perenne and Brassica oleracea. Feeding behaviour of X. index was studied on L. perenne, B. oleracea, S. dulcamara and L. esculentum. Feeding on the three latter species was predominantly at the root tip, sometimes with nematodes aggregated at the same tip. No differences were seen between the feeding behaviour on B. oleracea and that on S. dulcamara and L. esculentum.
TL;DR: The species of Axonchium with vaginal sclerotization, but without disc-like structure between vulva and vagina are redescribed.
Abstract: The species of Axonchium with vaginal sclerotization, but without disc-like structure between vulva and vagina are redescribed. This group is less uniform than that treated in the previous paper, it comprises the following species : A. coronatum (de Man, 1906), A. leptocephaluin Altherr, 1953, A. vaginatum Jairajpuri, 1965, A. valvulatum n.sp. and possibly A. macrophallum Thorne, 1939. Males, when present, have long and comparatively slender spicules.
TL;DR: Electron microscope autoradiography of virgin adult male Panagrellus silusiae pulse labelled with 3H-leucine revealed that protein synthesized in the hypodermal chords is inserted into the cuticles at the cuticle basement membrane invaginations.
Abstract: Electron microscope autoradiography of virgin adult male Panagrellus silusiae pulse labelled with 3H-leucine revealed that protein synthesized in the hypodermal chords is inserted into the cuticle at the cuticle basement membrane invaginations. From these foci protein migrates through the cuticle in a circumferential manner.