Variation in the life cycle and morphology of the tobacco host-race of Myzus persicae (Hemiptera: Aphididae) in relation to its geographical distribution

2002 ◽  
Vol 92 (4) ◽  
pp. 301-307 ◽  
Author(s):  
T.E. Kephalogianni ◽  
J.A. Tsitsipis ◽  
J.T. Margaritopoulos ◽  
E. Zintzaras ◽  
R. Delon ◽  
...  
Keyword(s):  
Life Cycle ◽  
Morphological Variation ◽  
Myzus Persicae ◽  
Western Europe ◽  
Classification Tree ◽  
Primary Host ◽  
Canonical Variates Analysis ◽  
Parametric Classification ◽  
Canonical Variates ◽  
Tree Method

AbstractMorphological variation and life cycle category were examined in 121 clones of Myzus persicae (Sulzer). The clones were collected from tobacco from three localities in Greece (Xanthi, Nea Efessos and Naphplion), one in Germany (Rheinstetten), one in France (Bergerac) and one in Spain (Madrid). Before morphometrics, all aphids were laboratory-reared on potato. The morphological variation was investigated using both canonical variates analysis and a novel non-parametric classification tree method. The life cycle category was examined by rearing the clones for three generations under short day conditions. In Nea Efessos a relative high proportion of clones was found to overwinter as eggs on the primary host. In the other regions all collected clones were non-holocyclic. Intermediate genotypes were found in all regions at percentages ranging from 4.0 to 24.0%. Androcyclic clones were found only in Xanthi, Greece (4.0%) and Rheinstetten, Germany (16.7%). The canonical variates analysis and the tree classification method revealed important intrapopulation polymorphisms in clones from Bergerac, Nea Efessos and Madrid. Both methods separated the populations originating from Greece from those collected elsewhere in western Europe. The observed morphological variation was probably due to genetic differences, since all clones were reared in a common environment. The results are discussed in relation to factors responsible for genetic divergence in M. persicae populations.

Host-correlated morphological variation of Myzus persicae (Hemiptera: Aphididae) populations in Greece

2000 ◽  
Vol 90 (3) ◽  
pp. 233-244 ◽  
Author(s):  
J.T. Margaritopoulos ◽  
J.A. Tsitsipis ◽  
E. Zintzaras ◽  
R.L. Blackman
Keyword(s):  
Cluster Analysis ◽  
Host Plant ◽  
Morphological Variation ◽  
Myzus Persicae ◽  
Prunus Persica ◽  
Classification Tree ◽  
Hierarchical Cluster ◽  
Canonical Variate ◽  
Primary Host ◽  
The North

Morphological variation in nine characters of 157 clones of Myzus persicae(Sulzer) was examined by multivariate analysis. The clones were collected from peach, Prunus persica, the primary host and the secondary hosts tobacco, Nicotiana tabacum, cabbage, Brassica oleracea, sugarbeet, Beta vulgaris and pepper Capsicum annuum. The 156 clones originated from various regions of Greece, both in the north, where a large part of the population has an annual bisexual generation on peach, and in more southerly regions, where populations are predominantly unisexual. One clone was collected from tobacco in Caserta, Italy. All clones were laboratory-reared on potato. Canonical variate analysis, hierarchical cluster analysis and a non-parametric classification tree method both revealed morphological differences associated with the host-plant on which they were collected. The scores of the first two canonical variates separated the tobacco-feeding clones from those originating from other secondary host-plants. However, in tobacco-growing areas the tobacco-feeding form predominated in spring populations on peach, and was sometimes found on other secondary hosts. In addition, using cluster analysis, the clones from tobacco which were sampled in the most southeasterly region showed a relatively large phenotypic distance from those collected further north and west. Moreover, clonal phenotypes were affected both by host plant and by long-term parthenogenetic rearing. However, in spite of these effects, the tobacco form was generally distinguishable from aphids originating from other hosts, indicating that the difference must have a genetic basis. In separate analyses of the clones originating from secondary hosts no association was found between morphology and either life cycle category or colour. Discriminant analysis showed that 89% of 1723 specimens could be correctly classified into the two groups.

Life cycle variation of Myzus persicae (Hemiptera: Aphididae) in Greece

2002 ◽  
Vol 92 (4) ◽  
pp. 309-319 ◽  
Author(s):  
J.T. Margaritopoulos ◽  
J.A. Tsitsipis ◽  
S. Goudoudaki ◽  
R.L. Blackman
Keyword(s):  
Life Cycle ◽  
Myzus Persicae ◽  
Host Plants ◽  
Primary Host ◽  
Low Frequencies ◽  
Cycle Variation ◽  
Ecological Aspects ◽  
North Eastern ◽  
Winter Crops ◽  
Almost All

AbstractDuring the years 1995–1999 the life cycle category of 2797 clones of Myzus persicae (Sulzer) was examined. The clones originated from primary and secondary hosts from different localities of North and Central Greece and the island of Crete in the south. Four different overwintering life cycle strategies were found that have also been described for M. persicae and other heteroecious species previously. A geographical variation was found in the proportion of holocyclic clones from tobacco and other secondary hosts associated with the abundance of the primary host in the sampling regions. In Central Macedonia, around the main peach-growing regions, the proportion of holocyclic clones was mostly above 50% and in some cases reached 100%. In localities of East Macedonia, holocyclic clones were also frequent. On the other hand, further south or in north-eastern Greece, where peach is not common, the proportion of holocyclic clones varied between 0 and 33%. Fifty seven percent of examined anholocyclic clones produced males under short day conditions, suggesting that androcyclic clones in Greece represent an important factor of genetic variability. Intermediate clones were sampled from all host-plants but at low frequencies (3.6% of total examined clones and 6.9% of non-holocyclic ones). Moreover, a regional variation was found in different colour forms feeding on tobacco plants. Red clones were predominant in regions where aphids overwinter parthenogenetically on weeds or winter crops. However, almost all clones from the primary host were green. The ecological aspects of life cycle variation are discussed.

Morphological variation in spring migrants of Myzus persicae (Sulz.) (Hemiptera, Aphididae): comparison of alatae from peach and mangold

1974 ◽  
Vol 64 (4) ◽  
pp. 595-604 ◽  
Author(s):  
J. A. T. Woodford ◽  
P. M. Lerman
Keyword(s):  
Morphological Variation ◽  
Myzus Persicae ◽  
Morphological Characters ◽  
Primary Host

AbstractSpring migrants of Myzus persicae (Sulz.) may be produced either by parthenogenetic aphids derived from fertilised eggs laid on the primary host, or by parthenogenetic aphids overwintering on secondary hosts. Five variates, based1 on eight morphological characters of alate M. persicae, are examined to investigate how to distinguish between alatae derived from populations that have overwintered by these two means. No single variate is adequate to identify correctly all specimens, although two of them, number of abdominal tubercles, and shape of the fenestra in the central abdominal patch, may each correctly assign as many as 90%.

Taxonomic revision of Australian species of Atyoida Randall (Crustacea : Decapoda : Atyidae), the genera Atyoida and Atya Leach

1982 ◽  
Vol 33 (2) ◽  
pp. 343 ◽  
Author(s):  
MJ Smith ◽  
WD Williams
Keyword(s):  
Life Cycle ◽  
Morphological Variation ◽  
Hawaiian Islands ◽  
Taxonomic Revision ◽  
Diagnostic Characters ◽  
Australian Species ◽  
Life Cycle Strategy ◽  
Distinguishing Features ◽  
Pacific Area

A reconsideration of the diagnostic characters of Atya Leach and Atyoida Randall supports their generic separation. Accordingly, Atyoida is reinstated as a full genus of which the distinguishing features are slender third peraeopods with a relatively short merus, a tapering endopod in the male first pleopod and protandry. It includes three species, A. bisulcata Randall from the Hawaiian Islands, A. pilipes (Newport) widespread in the Indo-Pacific area, and A. striolata (McCulloch & McNeill) found only in Australia. A. striolata is fully redescribed. Morphological variation throughout its range is slight; no subspecies are distinguishable. It is suggested that larvae hatch in estuaries and that protandry is an adaptive life-cycle strategy.

Abiotic versus biotic hierarchies in the assembly of parasite populations

Parasitology ◽  
2009 ◽  
Vol 137 (4) ◽  
pp. 743-754 ◽  
Author(s):  
T. K. ANDERSON ◽  
M. V. K. SUKHDEO
Keyword(s):  
Fundulus Heteroclitus ◽  
Classification Tree ◽  
Benthic Invertebrate ◽  
Life Cycles ◽  
Complex Life Cycles ◽  
Parasite Communities ◽  
Parametric Classification ◽  
The Common ◽  
Correct Category ◽  
Parasite Populations

SUMMARYThe presence or absence of parasites within host populations is the result of a complex of factors, both biotic and abiotic. This study uses a non-parametric classification tree approach to evaluate the relative importance of key abiotic and biotic drivers controlling the presence/absence of parasites with complex life cycles in a sentinel, the common killifish Fundulus heteroclitus. Parasite communities were classified from 480 individuals representing 15 fish from 4 distinct marsh sites in each of 4 consecutive seasons between 2006 and 2007. Abiotic parameters were recorded at continuous water monitoring stations located at each of the 4 sites. Classification trees identified the presence of benthic invertebrate species (Gammarus sp. and Littorina sp.) as the most important variables in determining parasite presence: secondary splitters were dominated by abiotic variables including conductance, pH and temperature. Seventy percent of hosts were successfully classified into the correct category (infected/uninfected) based on only these criteria. The presence of competent definitive hosts was not considered to be an important explanatory variable. These data suggest that the most important determinant of the presence of these parasite populations in the common killifish is the availability of diverse communities of benthic invertebrates.

scholarly journals High diversity in the regulatory region of Stx-converting bacteriophage genomes

2021 ◽  
Author(s):  
Toril Lindback ◽  
Annette Fagerlund ◽  
Marina Elisabeth Aspholm ◽  
Grzegorz Wegrzyn
Keyword(s):  
Life Cycle ◽  
Western Europe ◽  
Regulatory Region ◽  
Enterohemorrhagic Escherichia Coli ◽  
Replication Proteins ◽  
E Coli ◽  
Virulence Potential ◽  
Replication Region ◽  
Severity Of The Disease

Shiga toxin (Stx) is the major virulence factor of enterohemorrhagic Escherichia coli (EHEC), and the stx genes are carried by temperate bacteriophages (Stx phages). The switch between lysogenic and lytic life cycle of the phage, which is crucial for Stx production and for severity of the disease, is regulated by the CI repressor. CI maintain latency by preventing transcription of the replication proteins. Three EHEC phage replication units (Eru1-3) in addition to the classical lambdoid replication region have been described previously, and Stx phages carrying the Eru1 replication region were associated with highly virulent EHEC strains. In this study, we have classified the Eru replication region of 419 Stx phages. In addition to the lambdoid replication region and the three already described Erus, ten novel Erus (named Eru4 to Eru13) were detected. The lambdoid type, Eru1, Eru4 and Eru7 seem to be widely distributed in Western Europe. Notably, EHEC strains involved in severe outbreaks in England and Norway carry Stx phages with Eru1, Eru2, Eru5 and Eru7 replication regions. Phylogenetic analysis of CI repressors from Stx phages revealed eight major clades that largely separate according to Eru type. The classification of replication regions and CI proteins of Stx phages provides an important platform for further studies aimed to assess how characteristics of the replication region influence the regulation of phage life cycle and, consequently, the virulence potential of the host EHEC strain. IMPORTANCE: EHEC is an emerging health challenge worldwide and outbreaks caused by this pathogen tend to be more frequent and severe. Increased knowledge on how characteristics of the replication region influence the virulence of E. coli may be used for more precise identification of high-risk EHEC strains.

The inheritance of life-cycle differences in Myzus persicae (Sulz.) (Hem., Aphididae)

1972 ◽  
Vol 62 (2) ◽  
pp. 281-294 ◽  
Author(s):  
R. L. Blackman
Keyword(s):  
Life Cycle ◽  
Myzus Persicae ◽  
Imperial College ◽  
Short Photoperiod ◽  
Male Production ◽  
Field Station ◽  
Heterozygous Condition ◽  
Segregation Ratios ◽  
Genetically Determined

The response to short photoperiod (10 h) of the F1 and F2 sexual generations of Myzus persicae (Sulz.) resulting from a cross between oviparae from a holocyclic clone and males from an androcyclic clone were examined and compared in experiments done at Imperial College Field Station, England. F1 and F2 progeny segregated into three distinct phenotypes; holocyclic, androcyclic and intermediate. Intermediate clones reared at 10 h photoperiod produced alatae which were physiologically intermediate between gynoparae and virginoparae, because their progeny consisted of oviparae, apterous virginoparae and intermorphs. Intermediacy was not affected by temperature and seems to be genetically determined. Segregation ratios in the F1 and F2 indicate that the androcyclic condition is induced by a recessive ‘ switch-gene ’ which completely suppresses the production of sexual females, and partially suppresses male production. This gene could be present in the heterozygous condition in a large proportion of parthenogenetic lines of the aphid, and thus confer a latent potentiality for anholocycly on populations even where conditions will not regularly permit this method of overwintering. Conversely where anholocycly is strongly favoured many aphids would be homozygous for the recessive, androcyclic character, but the potential for gamic reproduction could remain widespread.

Coalition Governance in Western Europe

2021 ◽  
pp. 1-14
Author(s):  
Torbjörn Bergman ◽  
Bäck Hanna ◽  
Hellström Johan
Keyword(s):  
Life Cycle ◽  
Eastern Europe ◽  
Formation Process ◽  
Western Europe ◽  
Party Systems ◽  
Final Phase ◽  
Central Eastern Europe ◽  
Three Stages ◽  
Central Eastern ◽  
Western European

This chapter describes the ambitions of the volume. First, we build on the lessons from earlier studies of governments in Western and Central Eastern Europe to deepen our understanding of the coalition life cycle, covering the three stages of a government’s ‘life’, beginning with the formation process, then turning to the governance stage, and lastly turning to the final phase when governments eventually terminate. Second, we seek to capture how recent changes in the Western European party systems, which are also described here, influence the various stages of the coalition life cycle. Third, we are in particular interested in how coalition partners cooperate and make policy once a government has formed, aiming to contribute to the growing literature on the topic of coalition governance. The chapter ends with a description of the content of the volume.

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