Ultrastructural studies on the cuticle of the second-stage larvae of four root-knot nematodes: Meloidogyne hapla, M. javanica, M. incognita, and M. arenaria

1976 ◽  
Vol 54 (1) ◽  
pp. 96-100 ◽  
Author(s):  
P. W. Johnson ◽  
W. G. Graham
Keyword(s):  
Meloidogyne Hapla ◽  
Root Knot Nematodes ◽  
Ultrastructural Studies ◽  
Second Stage ◽  
Median Zone ◽  
Freezing Temperatures ◽  
Better Than

Ultrastructural studies on the cuticle of the second-stage larvae of Meloidogyne hapla, M. javanica, M. incognita, and M. arenaria showed that the cuticle structure in all four species was similar and consisted of six layers divisible into three zones: an outer trilaminate cortex, a two-layered median zone, and a basal striated zone. No association could be established between the structure of the cuticle of L2 M. hapla and the ability of the nematode to survive freezing temperatures significantly better than L2 M. incognita.

scholarly journals Occurrence and seasonal changes in the population of root-knot nematodes on honeybush (Cyclopia sp.)

2021 ◽  
Vol 58 (2) ◽  
pp. 202-212
Author(s):  
F. Y. Daramola ◽  
R. Malgas ◽  
A. P. Malan
Keyword(s):  
Population Density ◽  
Parasitic Nematodes ◽  
Western Cape ◽  
Meloidogyne Hapla ◽  
Plant Parasitic Nematodes ◽  
Severe Damage ◽  
Western Cape Province ◽  
Root Knot Nematodes ◽  
Second Stage ◽  
Important Group

Summary Root-knot nematodes in the genus Meloidogyne are an important group of plant-parasitic nematodes causing severe damage on agricultural crops worldwide. A study was conducted to identify the species of root-knot nematodes causing damage on honeybush monocultures and to assess the seasonal variations in the nematode population. Soil samples were collected from six experimental sites in Genadendal, Western Cape province of South Africa from 2016 to 2017. DNA was extracted from single-second stage juveniles and species identifi cation was done using species-specifi c sequence-characterised amplifi ed regions (SCAR) primers. Meloidogyne hapla and M. javanica were identifi ed from the sites. Mean population density of the nematodes varied significantly (p < 0.05) in the six sites, with the peak population being recorded in summer of 2017. The study suggests that seasonal variation in temperature and moisture could contribute to changes in the population density of root-knot nematodes in the soil.

Root-knot nematodes (Meloidogyne hapla) can modify the positive plant intraspecific diversity-productivity effect on red clover in clover-grass communities

2016 ◽  
Vol 102 ◽  
pp. 26-35 ◽  
Author(s):  
Xiaohui Guo ◽  
Jana S. Petermann ◽  
Conrad Schittko ◽  
Susanne Wurst
Keyword(s):  
Red Clover ◽  
Intraspecific Diversity ◽  
Meloidogyne Hapla ◽  
Root Knot Nematodes ◽  
Productivity Effect ◽  
Grass Communities

scholarly journals A new root-knot nematode, Meloidogyne vitis sp. nov. (Nematoda: Meloidogynidae), parasitizing grape in Yunnan

PLoS ONE ◽  
2021 ◽  
Vol 16 (2) ◽  
pp. e0245201
Author(s):  
Yanmei Yang ◽  
Xianqi Hu ◽  
Pei Liu ◽  
Li Chen ◽  
Huan Peng ◽  
...  
Keyword(s):  
New Species ◽  
Rapid Identification ◽  
Root Knot Nematode ◽  
Morphometric Traits ◽  
Head Region ◽  
Root Knot Nematodes ◽  
Lateral Field ◽  
Sequence Characterized Amplified Region ◽  
Second Stage ◽  
Labial Disc

An unknown root-knot nematode was found at high density on grape roots collected from Yunnan Province. Morphometric traits and measurements, isozyme phenotypes, and molecular analysis clearly differentiated this nematode from previously described root-knot nematodes. This new species is described, illustrated and named Meloidogyne vitis sp. nov. The new species can be distinguished from other Meloidogyne spp. by a unique combination of characters. Females display a prominent neck, an excretory pore is located on the ventral region between 23rd and 25th annule behind lips, an EP/ST ratio of approximately 2.5 (1.98–2.96), a perineal pattern with two large and prominent phasmids, and a labial disc fused with the medial lips to form a dumbbell-shaped structure. Males display an obvious head region, a labial disc fused with the medial lips to form a dumbbell-shaped structure, no lateral lips, a prominent slit-like opening between the labial disc and medial lips, a distinct sunken appearance of the middle of the medial lips, and four incisures in the lateral field. Second-stage juveniles are characterized by a head region with slightly wrinkled mark, a labial disc fused with the medial lips to form a dumbbell-shaped structure, a slightly sunken appearance of the middle of the medial lips, a slit-like amphidial openings between the labial disc and lateral lips, and four incisures in the lateral field. The new species has rare Mdh (N3d) and Est phenotypes (VF1). Phylogenetic analysis based on ITS1-5.8S-ITS2, D2D3 fragments of rDNA, and coxI and coxII fragments of mtDNA sequences clearly separated the new species from other root-knot nematodes, and the closest relative was Meloidogyne mali. Meloidogyne mali was collected for amplifying these sequences as mentioned above, which were compared with the corresponding sequences of new species, the result showed that all of these sequences with highly base divergence (48–210 base divergence). Moreover, sequence characterized amplified region (SCAR) primers for rapid identification of this new species were designed.

scholarly journals Plant regeneration from Crotalaria spectabilis hairy roots which showed inhibited growth of root-knot nematodes (Meloidogyne hapla and M. incognita) in vitro

2012 ◽  
Vol 29 (5) ◽  
pp. 425-430 ◽  
Author(s):  
Akiko Ohara ◽  
Hiroyuki Daimon ◽  
Yoji Momota ◽  
Dong Poh Chin ◽  
Masahiro Mii
Keyword(s):  
Plant Regeneration ◽  
Hairy Roots ◽  
Meloidogyne Hapla ◽  
Root Knot Nematodes ◽  
Crotalaria Spectabilis

scholarly journals Reproduction of Meloidogyne enterolobii in lettuce cultivars of the American group

2015 ◽  
Vol 33 (2) ◽  
pp. 147-150
Author(s):  
Érika CSS Correia ◽  
Norberto Silva ◽  
Marylia GS Costa ◽  
Silvia RS Wilcken
Keyword(s):  
Reproductive Potential ◽  
Egg Mass ◽  
Root Knot Nematodes ◽  
Second Stage ◽  
American Group ◽  
Meloidogyne Enterolobii ◽  
Meloidogyne Spp ◽  
Gall Index ◽  
Summer Time ◽  
Reproduction Factor

Lettuce is the main vegetable cultivated in Brazil, in volume and in marketed value. There are ranges of diseases which may affect lettuce crops, including those caused by root-knot nematodes (Meloidogyne spp.). We evaluated the reproductive potential of Meloidogyne enterolobii in 22 lettuce cultivars. The plants were inoculated with 5,000 eggs and eventuals second stage juveniles of nematode per pot, two days after the transplanting. 'Rutgers' tomato was used as standard for inoculum viability of M. enterolobii. We evaluated, 60 days after inoculation, the gall index, egg mass index and reproduction factor (RF). The 'Ithaca', 'Raider Plus', 'RS-1397', 'L-104', 'Challenge', 'IP-11', 'Classic', 'Salinas 88', 'Vanguard 75', 'Calona' and 'Desert Queen' were resistant to M. enterolobii with RF varying from 0.22 to 0.9, and the cultivars Lady Winterset, Robinson, Sonoma, Raider, Lucy Brown, Bnondaga, Summer Time, Taina, Sundevil and L-109 were susceptible to this nematode, with RF ranging from 1.06 to 5.73.

Isolate-by-cultivar interaction in root-knot nematodes Meloidogyne hapla, M. chitwoodi, and M. falla× on potato

1998 ◽  
Vol 76 (1) ◽  
pp. 75-82 ◽  
Author(s):  
J.G. Van der Beek ◽  
P.F.G. Vereijken ◽  
L.M. Poleij ◽  
C.H. Van Silfhout
Keyword(s):  
Meloidogyne Hapla ◽  
Root Knot Nematodes

scholarly journals Anaerobic Soil Disinfestation Reduces Viability of Sclerotinia sclerotiorum and S. minor Sclerotia and Root-Knot Nematodes in Muck Soils

2020 ◽  
Vol 110 (4) ◽  
pp. 795-804
Author(s):  
Andres D. Sanabria-Velazquez ◽  
Anna L. Testen ◽  
Ram B. Khadka ◽  
Zhe Liu ◽  
Fuqing Xu ◽  
...  
Keyword(s):  
Carbon Source ◽  
Sclerotinia Sclerotiorum ◽  
Wheat Bran ◽  
Carbon Sources ◽  
Ethanol Solution ◽  
Meloidogyne Hapla ◽  
Root Knot Nematodes ◽  
Soil Disinfestation ◽  
Anaerobic Soil Disinfestation ◽  
Muck Soil

Experiments were conducted to evaluate potential functional and mechanistic differences in the suppression of Sclerotinia sclerotiorum and S. minor and root-knot nematodes in muck soils by anaerobic soil disinfestation (ASD) using different carbon source amendments. Volatile compounds produced during ASD in muck soil amended with molasses, wheat bran, or mustard greens at 20.2 Mg/ha or a 2% ethanol solution significantly reduced the mycelial growth and number of sclerotia produced by both Sclerotinia spp. compared with the anaerobic control. In amended soils, acetic and butyric acids were detected in concentrations that reduced the viability of sclerotia of both pathogens. Higher concentrations of carbon dioxide were observed in ASD-treated soils, regardless of the amendment, than in the nonamended anaerobic control. Only amendment with wheat bran did not increase the production of methane gas during ASD compared with the controls. Meloidogyne hapla survival was completely suppressed in soils treated with ASD regardless of carbon source. Field trials were conducted in Ohio muck soil to assess survival of sclerotia of both Sclerotinia spp. The viability of sclerotia of both Sclerotinia spp. was significantly reduced in soil subjected to ASD amended with wheat bran (20.2 Mg/ha), molasses (10.1 Mg/ha), or wheat bran (20.2 Mg/ha) plus molasses (10.1 Mg/ha) compared with the controls. A consistent negative correlation between soil reduction and viability of sclerotia of both pathogens was observed. Wheat bran and molasses are both widely available amendments that can be used as ASD carbon sources for the management of soilborne pathogens in muck soils.

Comparison of host recognition, invasion, development and reproduction of Meloidogyne graminicola and M. incognita on rice and tomato

Nematology ◽  
2011 ◽  
Vol 13 (5) ◽  
pp. 509-520 ◽  
Author(s):  
Tushar K. Dutta ◽  
Stephen J. Powers ◽  
Brian R. Kerry ◽  
Hari S. Gaur ◽  
Rosane H.C. Curtis
Keyword(s):  
Meloidogyne Incognita ◽  
Host Recognition ◽  
Cortical Region ◽  
Root Knot Nematode ◽  
Root Tips ◽  
Root Knot Nematodes ◽  
Tomato Plants ◽  
Meloidogyne Graminicola ◽  
Second Stage ◽  
Tomato Roots

AbstractThe rice root-knot nematode Meloidogyne graminicola normally infects rice, wheat and several other graminaceous plants. Meloidogyne incognita is a serious pest of dicotyledonous crops, although it can infect and reproduce on some cereals. This paper demonstrates and compares host recognition, development and reproduction of these two species of root-knot nematodes on rice and tomato plants. Attraction bioassays in pluronic gel clearly showed that M. incognita preferred tomato roots to rice or mustard roots, whilst M. graminicola was more attracted towards rice compared with tomato or mustard roots. Based on the attraction data from this study, it can be hypothesised that either: i) the blend of attractants and repellents are different in good and poor hosts; or ii) relatively long-range attractants, together with shorter-range repellents, might affect nematode movement patterns. Some host specific attractants might also be involved. Meloidogyne incognita was able to invade and develop to adult female but did not produce eggs in rice roots. By contrast, M. graminicola developed and reproduced faster on both rice and tomato plants compared with M. incognita. Nevertheless, second-stage juveniles of both these root-knot nematodes showed a similar pattern of distribution inside the roots, preferring to accumulate at the root tips of rice or in the vascular cylinder and cortical region of tomato.

scholarly journals Comparison of estimators in one-phase two-stage Poisson sampling in forest inventories

2012 ◽  
Vol 42 (10) ◽  
pp. 1865-1871 ◽  
Author(s):  
Daniel Mandallaz ◽  
Alexander Massey
Keyword(s):  
Small Area ◽  
Two Stage ◽  
Random Sample Size ◽  
Poisson Sampling ◽  
Second Stage ◽  
Forest Inventories ◽  
Unbiased Estimates ◽  
The Mean ◽  
Concentric Circles ◽  
Better Than

In the context of Poisson sampling, numerous adjustments to classical estimators have been proposed that are intended to compensate for inflated variance due to random sample size. However, such adjustments have never been applied to extensive forest inventories. This work investigates the performances of four estimators for the timber volume in one-phase two-stage forest inventories, where trees in the first stage are selected, at the plot level, by concentric circles or angle-count methods and a subset thereof are selected by Poisson sampling for further measurements to get a better estimation. The original two-stage estimator is the sum of two components: the first is the mean of Horwitz–Thompson estimators using simple volume approximations, based on diameter and species alone, of all first-stage trees in each inventory plot, and the second is the mean of Horwitz–Thompson estimators based on the differences between the simple volume approximations and refined volume determinations based on further diameter and height measurements on the second-stage trees within each inventory plot. This two-stage estimator is particularly useful because it provides unbiased estimates even if the simple prediction model is not correct, which is particularly important for small area estimation. The other three estimators rely on adjustments of the second component of the original estimator that are adapted from estimators proposed in the literature by L.R. Grosenbaugh and C.-E. Särndal. It turns out that these adjustments introduce a negligible bias and that the original simple estimator performs just as well or even better than the new estimators with respect to the variance.

scholarly journals Design and Analysis of a Split Deswirl Vane in a Two-Stage Refrigeration Centrifugal Compressor

2014 ◽  
Vol 6 ◽  
pp. 130925 ◽  
Author(s):  
Jeng-Min Huang ◽  
Yue-Hann Tsai
Keyword(s):  
Centrifugal Compressor ◽  
Rotation Angle ◽  
Guide Vane ◽  
Low Flow ◽  
Working Fluid ◽  
Inlet Guide Vane ◽  
Two Stage ◽  
Double Row ◽  
Second Stage ◽  
Better Than

This study numerically investigated the influence of using the second row of a double-row deswirl vane as the inlet guide vane of the second stage on the performance of the first stage in a two-stage refrigeration centrifugal compressor. The working fluid was R134a, and the turbulence model was the Spalart-Allmaras model. The parameters discussed included the cutting position of the deswirl vane, the staggered angle of two rows of vane, and the rotation angle of the second row. The results showed that the performance of staggered angle 7.5° was better than that of 15° or 22.5°. When the staggered angle was 7.5°, the performance of cutting at 1/3 and 1/2 of the original deswirl vane length was slightly different from that of the original vane but obviously better than that of cutting at 2/3. When the staggered angle was 15°, the cutting position influenced the performance slightly. At a low flow rate prone to surge, when the second row at a staggered angle 7.5° cutting at the half of vane rotated 10°, the efficiency was reduced by only about 0.6%, and 10% of the swirl remained as the preswirl of the second stage, which is generally better than other designs.

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