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In search of an explanatory model representing developmental rates of Oulema duftschmidi. Fourth Study Days on Numerical, Statistical and Computer Based Methods for Crops and Forests Protection
No full textCoinciding development of winter wheat and leaf beetles along an Alpine transect
No full textThe degree of temporal coincidence in the development of winter wheat (Triticum aestivum L.) and the cereal leaf beetles Oulema melanopus (L.) and Oulema duftschmidi (Redtenbacher, 1874) was studied by means of explanatory phenology models. Temperature and photoperiod control crop development, whereas oviposition and development of eggs and larvae of the two beetles depend on temperature and crop phases. The models parametrized with literature data satisfactorily represented crop and prepupal insect development at several Swiss and Italian locations.
The successfully validated models were used for representing multiannual crop and insect development at seven locations on a European transect between the Danube river in the North and the Po River in the South. Depending on temperature and photoperiod, the crop phases occurred at different time periods but were generally of similar durations. The shifting of the crop phases exposed the cereal leaf beetles to environmental conditions which were similar during oviposition and slightly different as the growing season progressed. The simulated oviposition and prepupal survivorship was much higher for O. melanopus than for O. duftschmidi but did not differ between the locations. The crop phase-dependent mortality (Mc) was consistently higher for O. duftschmidi than for O. melanopus, whose Mc increased with increasing altitude.
The extent of coinciding development was investigated by means of the summed larval development rates divided by the summed wheat development rate. During the oviposition period the insect development was coincident with wheat development. With time progression, however, the temperature difference between the locations increased causing an incomplete coincidence in the development of wheat and cereal leaf beetles. These results support the hypothesis that the extent of coinciding development of the three species is largely controlled by temperature and photoperiodic conditions
Modello stocastico-biofisico per lo sviluppo di una coorte di Oulema duftschmidi a temperature costanti
No full textComments on the dynamics of insect population assemblages and sampling plans for aphids in commercial alpine yarrow fields
No full textAchillea collina Becker ex Rchb. (yarrow) is a medicinal plant grown for commercial purposes in southern Switzerland and northern Italy. The economically most relevant population assemblage is organized around the phloem feeding aphids Macrosiphoniella millefolii (De Geer), Aphis spiraecola Patch and Coloradoa achilleae Hille Ris Lambers. The study is a contribution to explaining the dynamics of this assemblage in two Alpine fields, on the basis of multitrophic population interactions. The method consisted in stratifying the field and taking random samples of yarrow stems and leaves, aphid numbers, and numbers of adult coccinellids and mummified aphids throughout the growing period. There were no significant differences in aphid densities between the strata (α = 0.05; F = 1.561; P = 0.138). Once the photoperiod reaches 14 h, a time window opens for stem elongation and reproductive development that creates suitable conditions for the aphids. There are indications for an influence of the plant and a possibly limited effect of natural enemies on aphid infestations. The coefficients b (1.920, 1.917) and a (3.911, 14.539) of Taylor's power law indicate aggregated distributions of M. millefolii and A. spiraecola. To obtain a reliable density estimate, 100 or 400 plants should be sampled for M. millefolii and A. spiraecola, respectively. An enumerative sequential sampling plan appears to be more efficient than the enumerative fixed sample size sampling plan
The performance of Macrosiphoniella millefolii and Myzus persicae on Achillea collina
No full textThis paper compares the development of the polyphagous aphid Myzus persicae Sulzer, considered as a generalist, and the oligophagous aphid Macrosiphoniella millefolii (De Geer), considered as a specialist, on yarrow (Achillea collina Becker ex Reichenbach). Yarrow is a medicinal plant rich in bioactive secondary metabolites that have possible effects on the development of phytophages, including aphids. Age specific life tables for cohorts developing under different constant temperatures were constructed and analyzed using standard techniques, and complemented with Jackknife estimates of the intrinsic rate of increase and its standard error. The parthenogenetic wingless morphs of the two species differed in the immature developmental time and survival, and in adult fecundity and life span. At high temperatures, the intrinsic rate of increase as the overall metric of performance tended to be higher for the generalist than for the specialist aphid species, while the opposite appears to occur at low and medium temperatures. Further insight into the complex interactions between yarrow and aphids requires that their genetic diversity is taken into account. The study of yarrow-aphid-natural enemy population interactions requires additional information on biomass dynamics, aphid morph differentiation and the performance of biological control agents
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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