1,720,988 research outputs found
Mating behavior and vibrational communication of the meadow spittlebug Philaenus spumarius
No full textThe effect of distance between parasitoid and host on the parasitism of Psyttalia concolor (Szépligeti) in organic olive orchards
No full textBactrocera oleae (Rossi) is a major pest of olive fruits. Biological control of olive fruit fly mainly relies on the activity of the Braconid species Psyttalia concolor (Szépligeti), which parasitizes Bactrocera oleae at the larval stage. Parasitism tests have been carried out at the insect growing facility (insectariums) of the Mediterranean Agronomic Institute of Bari (C.I.H.E.A.M.). The critical point of the use of P. concolor as a biological control agent in organic olive crop is the assessment of its effectiveness against B. oleae. Its lower presence in fruits of cultivated olives rather than in small fruits of wild olives suggests an influence of the size of the fruit, and of the thickness of its pulp on the parasitization of P. concolor. Therefore, the aim of this research was to investigate the capacity of the females of P. concolor to lay their eggs into the target host according to the distance existing between the female and the host larva. In these tests, the substitution host Ceratitis capitata was used and parasitism of P. concolor was tested at different distances (0, 0.5, 1, 1.5, 2, 2.5 and 3 mm) to the host larvae at different times (7 min, 15 min, 30 min and 60 min) of interaction.
Predetermined distances between the parasitoids and the target larvae were arranged by locating the flying females into cubical cages of 40x40x40 cm with Plexiglas walls and the open roof covered with a tulle tissue in order to avoid that any insects from outside may enter the cages, and to allow the females to protrude their ovipositors. On these roofs, plastic cylinders containing the target larvae were placed with the open bases arranged with a tulle tissue, to allow the contact with the parasitoid females. Considering the width of the tissues negligible, distances were set by metal separators with increasing thickness.
Parasitism level at 7 min was not significantly different at 2, 2.5 and 3 mm distances. Parasitism level was the highest at 0, 0.5, and 1 mm distances with no significant changes. Parasitism at 15 min showed a high variability according to the distances. The highest level resulted at 0.5 and 1 mm distances, the lowest at 3 mm distance. At 30 min interaction, the highest level of parasitism was at 0 mm distance, whilst at 1 and 1.5 mm the level was lower with no significant changes. Again, parasitism level was the lowest at 3 mm distance. The highest level of parasitism at 60 min was detected at 1.5 mm distance and was as lower as the distance increased.
In conclusion, the study showed that the females of P. concolor were not able to parasite the target larvae at distances higher than 2.5 mm. Generally, the parasitism level decreases with the increase of the distance between target larvae and parasitoid females. At the lowest distances (0, 0.5 and 1 mm) hyper parasitism occurred and the target pupae were killed, but also the development of the parasitoids into adults was very difficult for nutrient unavailability. Biological control of P. concolor against B. oleae larvae may give satisfactory results only if the depth at which the target larvae are located into the olive drupes is not higher than 2 or 2.5 mm from the surfac
Influenza delle caratteristiche chimico-fisiche del suolo e della gestione fitosanitaria sulla concentrazione di solfati in oliveti e vigneti biologici della Puglia
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Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Full text link“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
Full text linkWe 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
Risposte di Trissolcus mitsukurii alle tracce chimiche volatili rilasciate da Halyomorpha halys
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