Further Observations on the Morphology of Heterodera schachtii, with Remarks on the Bionomics of a strain attacking Mangolds in Britain

1929 ◽  
Vol 7 (3) ◽  
pp. 119-140 ◽  
Author(s):  
Marjorie J. Triffitt
Keyword(s):  
Sugar Beet ◽  
Developmental Stages ◽  
Morphological Characters ◽  
Heterodera Schachtii ◽  
Adult Males ◽  
Morphological Variations ◽  
Size And Shape ◽  
Morphological Studies ◽  
Comparative Survey

In a previous publication the morphological characters of a strain of H. schachtii specialised on the potato in Lincolnshire were discussed. The size and shape of the brown cysts, size of the eggs and first stage larvæ and the general characters of the adult males of this strain were compared with those of a strain attacking potatoes in Rostock, Mecklenburg, for which the specific name H. rostochiensis was suggested by Wollenweber 1923.Considerable dimensional variations were found to exist in the Lincolnshire strain, and a study of the literature on the morphological characters of H. schachtii specialised on sugar-beet and oats, showed equally wide divergencies between the findings of different workers. A certain amount of preserved material of infected roots of beet and oats being available to the writer, as many developmental stages as possible were extracted from these, on which similar morphological studies were carried out. Thus a fairly complete comparative survey of H. schachtii specialised on beet, oats and potatoes was completed, and the morphological variations between the strains were found to be insufficient to justify the separation of the strain specialised on potato from those on beet and oats. The name H. rostochicnsis was, therefore, deemed a synonym for H. schachtii.

The monoxenic culture of beet eelworm (Heterodera schachtii Schm.) on excised roots of sugar beet (Beta vulgaris L.)

Parasitology ◽  
1964 ◽  
Vol 54 (2) ◽  
pp. 289-293 ◽  
Author(s):  
F. Moriarty
Keyword(s):  
Sugar Beet ◽  
Beta Vulgaris ◽  
Lateral Roots ◽  
Heterodera Schachtii ◽  
Chemical Stimulus ◽  
Adult Males ◽  
Wound Reaction ◽  
Maximum Root ◽  
Research And Education ◽  
Tissue Reactions

A method is described for obtaining sterile second-instar larvae of beet eelworm, Heterodera schachtii Schm., and culturing them to the adult stage on sterile excised roots of sugar beet, Beta vulgaris L. It was shown that beet eelworm is a primary pathogen, for sound uninjured radicles were invaded by larvae, and normal development of adult males and females followed. No females were fertilized, and no eggs were produced, which suggested that parthenogenesis cannot occur. Eelworm development stimulated the production of lateral roots. More adult females developed on radicles inoculated 24 hr. after excision than on radicles inoculated 72 hr. after excision, which may be related to the occurrence of maximum root extension during the first few days after excision. It is suggested that there are two parts in root tissue reactions: a thickening of cell walls as a wound reaction to mechanical injury, and formation of a syncytium in response to a chemical stimulus from the eelworm.I thank my wife for assistance with this work, which was financed by the Sugar Beet Research and Education Committee.

The development of the beet eelworm Heterodera schachtii Schm. in monoxenic culture

Parasitology ◽  
1965 ◽  
Vol 55 (4) ◽  
pp. 719-722 ◽  
Author(s):  
F. Moriarty
Keyword(s):  
Sugar Beet ◽  
Adult Stage ◽  
Aqueous Suspension ◽  
Heterodera Schachtii ◽  
Adult Males ◽  
Acid Fuchsin ◽  
Main Root ◽  
Culture Methods ◽  
Rate Of Development ◽  
Root Axis

The rate of development of sterile 2nd-instar beet eelworm (Heterodera schachtii Schm.) larvae to the adult stage on excised sterile roots of sugar beet (Beta vulgaris L.) was studied.Culture methods were as previously described (Moriarty, 1964). Sterile excised sugar-beet roots were placed on White's medium gelled with 0·75 % agar, inoculated with about 0·1 ml of an aqueous suspension containing several hundred sterile 2nd-instar eelworm larvae, and kept at 25 ± 0·5 °C. After 24 h the roots were transferred to liquid White's medium. Two roots were stained in acid fuchsin lactophenol (Goodey, 1963) every 24 h, for 19 days. Later, the length of main root axis and total length of laterals were measured, the number of laterals counted, the eelworms dissected out and the larval instars identified (Raski, 1950).When roots were removed for staining, the liquid medium was examined for eelworms. Only adult males were ever found, and these are included in the counts in Table 1.The rate of development of larvae varied greatly, about half did not develop beyond the 2nd instar (Table 1) and from the fifth day onwards some atrophied. One root in which many adults developed was kept 41 days before killing and staining: there were still some 2nd-instar larval cuticles, devoid of contents except for the buccal stylet, and presumably dead. The average number of all instars found per root did not decline during the 19 days of observations: therefore few of the atrophying larvae could have been missed. The percentage of larvae that entered the roots was variable and small.

Breeding and usage of sugar beet cultivars and hybrids resistant to sugar beet nematode Heterodera schachtii

2015 ◽  
Vol 2 (1) ◽  
pp. 12-22 ◽  
Author(s):  
L. Pylypenko ◽  
K. Kalatur
Keyword(s):  
Sugar Beet ◽  
Sugar Content ◽  
Production Capacity ◽  
Nematode Resistance ◽  
Control Measures ◽  
Heterodera Schachtii ◽  
Yield Reduction ◽  
Agricultural Practice ◽  
Germplasm Exchange ◽  
Good Agricultural Practice

Heterodera schachtii Schmidt, 1871 is one of the most economically important pests of sugar beet (Beta vulgaris L.) worldwide. It is also widespread in most sugar beet growing regions in Ukraine causing serious yield reduction and decreasing sugar content of sugar beet in infested fi elds. An advanced parasitic strategy of H. schachtii is employed to support nematode growth, reproduction and harmfulness. In intensive agriculture systems the nematode control measures heavily rely on nematicides and good agricultural practice (crop rota- tion in the fi rst place). But alternative strategies based on nematode resistant sugar beet cultivars and hybrids are required as none of nematicides approved for the open fi eld application are registered in Ukraine. Here we review the achievements and problems of breeding process for H. schachtii resistance and provide the results of national traditional breeding program. Since the beginning of 1980s fi ve sugar beet cultivars (Verchnyatskyi 103, Yaltuschkivska 30, Bilotcerkivska 45, BTs-40 and Yuvileynyi) and seventeen lines partly resistant or toler- ant to H. schachtii have been obtained throughout targeted crossing and progenies assessment in the infested fi elds. The further directions for better utilization of genetic sources for nematode resistance presented in na- tional gene bank collection are emphasized. There is a need for more accurate identifi cation of resistance genes, broader application of reliable molecular markers (suitable for marker-assisted selection of nematode resistant plants in the breeding process) and methods for genetic transformation of plants. Crop cash value and national production capacity should drive the cooperation in this fi eld. Knowledge as well as germplasm exchange are thereby welcomed that can benefi t breeding progress at national and international level.

Readjustment of the Standard ASUDAS to Encompass Dental Morphological Variations in Plio-Pleistocene Hominins

2018 ◽  
Vol 30 (1-2) ◽  
pp. 32-48
Author(s):  
M. Louail ◽  
S. Prat
Keyword(s):  
Phylogenetic Relationships ◽  
Homo Sapiens ◽  
Initial Study ◽  
Morphological Characters ◽  
State University ◽  
Arizona State University ◽  
Dental Anthropology ◽  
Morphological Variations ◽  
Fossil Hominins ◽  
Fossil Hominin

The standard ASUDAS scoring system (Arizona State University Dental Anthropology System) is used to assess dental morphological variations in modern humans. It is also frequently used to study, score, and compare morphological variations in fossil hominin taxa and to examine their phylogenetic relationships. However, using ASUDAS in studies of this type is under debate because it is based on modern Homo sapiens populations and does not appear to cover all variations observed in fossil Plio-Pleistocene homi- nins. Our observations and coding of 178 dentals casts of Plio-Pleistocene specimens based on ASUDAS and from the literature have confirmed the need to adapt the standard system to fossil hominins. In this initial study, we propose that the scoring procedures for some morphological characters need to be readjusted, while others could be standardized following the ASUDAS system.

Baetis majus sp. nov., new species of mayfly (Ephemeroptera: Baetidae) from Far East of Russia

Zootaxa ◽  
2021 ◽  
Vol 4965 (3) ◽  
pp. 541-557
Author(s):  
TATIANA M. TIUNOVA ◽  
ALEXANDER A. SEMENCHENKO ◽  
XIAOLI TONG
Keyword(s):  
New Species ◽  
Russian Far East ◽  
Far East ◽  
Morphological Characters ◽  
Species Group ◽  
Morphological Studies ◽  
Nearest Neighbours ◽  
Differential Identification ◽  
Coi Sequences ◽  
Western Palaearctic

A new species, Baetis majus Tiunova sp. nov., is described and illustrated based on larvae and reared adults discovered in the Russian Far East. The differential identification of this species was determined by the characteristics of other representatives of the genus Baetis Leach, including subgenera Baetis Leach and Tenuibaetis Kang & Yang from Eastern and Western Palaearctic, Nearctic and Oriental regions. In addition to morphological studies, DNA barcoding of the described species with average intraspecific K2P distances to nearest neighbours is documented. We reconstructed the phylogenetic relationships of all available cytochrome c oxidase subunit I (COI) sequences of the subgenera of Baetis and Tenuibaetis from four regions. Bayesian analysis using 47 morphological characters additional to partial COI sequences did not allow to determine the species-group of the Baetis genus to which the described species belongs. 

Extrinsic Inter- and Intra-specific Competition in Parasitoid Wasps

2021 ◽  
Vol 67 (1) ◽  
Author(s):  
Paul J. Ode ◽  
Dhaval K. Vyas ◽  
Jeffrey A. Harvey
Keyword(s):  
Developmental Stages ◽  
Interference Competition ◽  
Apparent Competition ◽  
Annual Review ◽  
Publication Date ◽  
Natural Ecosystem ◽  
Adult Males ◽  
Alternate Host ◽  
Adult Females ◽  
Behavioral Mechanisms

The diverse ecology of parasitoids is shaped by extrinsic competition, i.e., exploitative or interference competition among adult females and males for hosts and mates. Adult females use an array of morphological, chemical, and behavioral mechanisms to engage in competition that may be either intra- or interspecific. Weaker competitors are often excluded or, if they persist, use alternate host habitats, host developmental stages, or host species. Competition among adult males for mates is almost exclusively intraspecific and involves visual displays, chemical signals, and even physical combat. Extrinsic competition influences community structure through its role in competitive displacement and apparent competition. Finally, anthropogenic changes such as habitat loss and fragmentation, invasive species, pollutants, and climate change result in phenological mismatches and range expansions within host–parasitoid communities with consequent changes to the strength of competitive interactions. Such changes have important ramifications not only for the success of managed agroecosystems, but also for natural ecosystem functioning. Expected final online publication date for the Annual Review of Entomology, Volume 67 is January 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

New species and findings of Pagastia Oliver (Diptera: Chironomidae: Diamesinae) from Central Asia, with DNA barcoding of known species of the genus

Zootaxa ◽  
2021 ◽  
Vol 4951 (3) ◽  
pp. 559-570
Author(s):  
EUGENYI A.  MAKARCHENKO ◽  
ALEXANDER A. SEMENCHENKO ◽  
DMITRY M. PALATOV
Keyword(s):  
New Species ◽  
Central Asia ◽  
Cytochrome Oxidase ◽  
Phylogenetic Trees ◽  
Morphological Characters ◽  
Molecular Data ◽  
Adult Males ◽  
Cytochrome Oxidase Subunit ◽  
Oxidase Subunit ◽  
Coi Sequences

Chironomids of the genus Pagastia Oliver (Diamesinae, Diamesini) from the mountains of Central Asia are revised using both morphological characters and molecular data. Illustrated descriptions of the adult male Pagastia (P.) caelestomontana sp. nov. from Kirgizstan and Tajikistan, P. (P.) hanseni sp. nov. from Tajikistan, and record of a finding apparently a new species P. (P.) aff. lanceolata (Tokunaga) from Tajikistan as well as an updated a key to the determination of the adult males of all known species of Pagastia are provided. A phylogenetic framework is reconstructed based on two mitochondrial genes cytochrome oxidase subunit I (COI) sequences of 34 samples belonging to 7 species of the genus Pagastia and cytochrome oxidase subunit II (COII) available for most samples. Phylogenetic trees of some known species of the genus Pagastia were reconstructed using the combined dataset and Bayesian inference (BI) and Maximum Likelihood (ML) methods. The interspecific K2P distances between seven Pagastia species including P. (P.) caelestomontana sp. nov., P. (P.) hanseni sp. nov. and undescribed P. (P.) aff. lanceolata (Tokunaga) are 6.3–13.2 which corresponding to species level. 

Phenology of the sugar beet weevil, Bothynoderes punctiventris Germar (Coleoptera: Curculionidae), in Croatia

2018 ◽  
Vol 109 (4) ◽  
pp. 518-527
Author(s):  
Z. Drmić ◽  
M. Čačija ◽  
H. Virić Gašparić ◽  
D. Lemić ◽  
R. Bažok
Keyword(s):  
Sugar Beet ◽  
Dynamic Models ◽  
Developmental Stages ◽  
Adult Population ◽  
Regional Scale ◽  
Adult Emergence ◽  
Soil Samples ◽  
Population Characteristics ◽  
Degree Day ◽  
Development Threshold

AbstractThe sugar beet weevil (SBW), Bothynoderes punctiventris Germar, 1824, is a significant pest in most of Eastern Europe. Here, the SBW is described and its seasonal activity characterized, in terms of its different developmental stages in relation to Julian days (JDs), degree-day accumulations (DDAs), and precipitation, as a key to improving monitoring and forecasting of the pest. The phenology and population characteristics of SBW were investigated in sugar beet fields in eastern Croatia over a 4-year period (2012–2015). By using the degree-day model (lower development threshold of 5°C, no upper development threshold, biofix 1 January), the first emergence of overwintering adults was determined as becoming established when the DDA reached 20. The adult emergence was completed when the DDA reached 428. SBW males emerged first, following which the females dominated the adult population. Overwintering adults were present in the field until early July. In August, adults of the offspring generation began to appear. The eggs laid by the overwintering generation required, on average, 10–15 days to develop into larvae; however, eggs were found in soil samples over a period of 102 days (between JDs 112 and 214). Larvae were present in the soil samples over a period of a maximum of 143 days (the first larvae were established on JD 122 and the last one on JD 265), and pupae were established in the soil over a period of 102 days (between JDs 143 and 245). This study provides important data for understanding SBW population dynamics and developing potential population dynamic models for pest forecasting on a regional scale.

scholarly journals An assessment of the taxonomic validity of three species of marsupial frogs (Anura: Hemiphractidae: Gastrotheca) from the Yungas of Bolivia based on external morphology and cranial osteology

Zootaxa ◽  
2021 ◽  
Vol 5068 (2) ◽  
pp. 211-239
Author(s):  
CLAUDIA LANSAC ◽  
RODRIGO AGUAYO ◽  
IGNACIO DE LA RIVA
Keyword(s):  
Principal Component ◽  
Taxonomic Status ◽  
Ct Scanning ◽  
Developmental State ◽  
Morphological Characters ◽  
Biological Entity ◽  
Nominal Species ◽  
Linear Discriminant ◽  
Morphological Studies ◽  
Cranial Osteology

The genus Gastrotheca (Anura: Hemiphractidae) is a group of marsupial frogs particularly diverse in Andean regions. Several taxonomic studies of this genus have been conducted in the humid cloud forests—or Yungas—of the Andean eastern slopes of central Bolivia (departments of Cochabamba and Santa Cruz). Yet, the distinction among three species that occur sympatrically in these forests, G. lauzuricae (proposed as a junior synonym of G. coeruleomaculatus in 2015), G. piperata, and G. splendens, remains unclear since the morphological characters that purportedly support their differentiation are variable and partly shared among them. We have carried out external morphological studies, including multivariate morphometric analyses, to assess how they support the taxonomic status of these three species. We also evaluated characters of the cranial osteology of a sample of six individuals using micro CT-scanning. Principal component and linear discriminant analyses resulted in a great overlap among the putative species. Cranial osteological comparisons did not reveal highly significant differences among them, but suggested that different degrees of hyperossification could be related to the developmental state of individuals. Our results indicate that most morphological and osteological reported differences between the three species likely represent intraspecific variation. Thus, we propose that the three nominal species belong to a single biological entity, for which the name Gastrotheca splendens (Schmidt, 1857) has priority. We also restrict the name Gastrotheca coeruleomaculatus (Werner, 1899) to externally similar congeneric populations from the Yungas forests of department of La Paz, but highlighting the need of a detailed evaluation of their taxonomic identity.  

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