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Wild olive seed weevil, Anchonocranus oleae Marshall (Coleoptera: Curculionidae), in cultivated olives in South Africa
Full text linkWild olive seed weevil, Anchonocranus oleae Marshall, larvae as well as oviposition and feeding damage were recorded in cultivated olives during a recent study on olive seed wasps in South Africa. Prematurely dropped fruit and fruit picked at harvest in two orchards near Stellenbosch and Agter- Paarl were examined regularly for olive seed wasp infestation over three seasons. In addition, olives were collected over a wider area of the olive growing regions of the Western Cape province for a survey to determine olive seed wasp distribution. DNA barcoding confirmed the identity of weevil larvae in kernels as A. oleae. The number of A. oleae larvae found in olive seeds and the number of olives with weevil oviposition or feeding damage were low. The presence of larvae and weevil damage in two orchards in the survey with no wild olive trees in close proximity suggest that the weevil could breed and persist in cultivated olive orchards. Currently A. oleae is not of economic concern, but if infested olives are discarded at harvest and left in orchards, the weevils could complete their development in the kernels and numbers could increase to damaging levels
Eupelmus spermophilus Silvestri (Hymenoptera: Chalcidoidea), an Indigenous Olive Seed Wasp Potentially Harmful to Olive Growing in the Western Cape, South Africa
No full textThe objectives of this study were the specific taxonomic confirmation of the main olive seed wasp (OSW) attacking commercial olives in the Western Cape, to investigate monitoring methods and seasonal occurrence of OSW, to determine the potential economic damage of infestations, and to ascertain the geographic distribution of OSW in the regions where olives are cultivated in the Western Cape. Morphological and molecular methods were used to identify all the species obtained from cultivated olives at two trial sites near Stellenbosch and Agter-Paarl. Eupelmus spermophilus Silvestri (Hymenoptera: Chalcidoidea) was by far the most frequent and widespread olive seed wasp. Monitoring with yellow sticky traps over three seasons indicated OSW presence in orchards when olives were small enough for OSW to oviposit in, but traps were not reliable indicators of OSW infestation levels. Prematurely dropped olives, collected from February until harvest over three seasons, and olives picked at harvest were examined for OSW infestation. Total yield for each data tree was recorded at harvest, and yield loss due to OSW infestation calculated. Economically significant yield losses occurred sporadically. Fruits collected from both cultivated and wild olive trees indicated that OSW occurs in most olive-growing regions of the Western Cape. OSW does not pose a significant threat to the local olive industry as a whole and cannot be considered a key pest of olives, but during some seasons it can affect production yields where wild olive trees are located near commercial olive groves
New mitochondrial gene rearrangement in Psyttalia concolor, P. humilis and P. lounsburyi (hymenoptera: Braconidae), three parasitoid species of economic interest
Full text linkThe family Braconidae consists mostly of specialized parasitoids, some of which hold potential in biocontrol of agricultural pests. Psyttalia concolor, Psyttalia humilis and Psyttalia lounsburyi are parasitoids associated with Bactrocera oleae, a major pest of cultivated olives. The native range of Psyttalia concolor is the Mediterranean, and P. humilis and P. lounsburyi are native to sub-Saharan Africa. This study reports the mitochondrial genomes of the three species, thus laying the foundation for mitogenomic analyses in the genus Psyttalia. Comparative mitogenomics within Braconidae showed a novel gene arrangement in Psyttalia in involving translocation and inversion of transfer RNA genes. The placement of Psyttalia in the subfamily Opiinae was well-supported, and the divergence between Psyttalia and its closest relative (Diachasmimorpha longicaudata) was at ~55 MYA [95% highest posterior density (HPD): 34–83 MYA]. Psyttalia lounsburyi occupied the most basal position among the three Psyttalia, having diverged from the other two species ~11 MYA (95% HPD: 6–17 MYA). Psyttalia concolor and P. humilis were recovered as sister species diverged at ~2 MYA (95% HPD: 1.1–3.6 MYA). This phylogeny combining new sequences and a set of 31 other cyclostomes and non-cyclostomes highlights the importance of a comprehensive taxonomic coverage of Braconidae mitogenomes to overcome the lack of robustness in the placement of several subfamilies
DNA-Based Identification of Larvae Offers Insights into the Elusive Lifestyles of Native Olive Seed Wasps in South Africa
No full textWild and cultivated olives in the Western Cape of South Africa are direct or indirect hosts to a high diversity of Braconidae and Chalcidoidea wasps. Olive-associated Braconidae are known to parasitise the larvae of Bactrocera oleae (Rossi), and probably also Bactrocera biguttula (Bezzi). The lifestyle of olive-associated Chalcidoidea is not fully understood, and may include phytophagous, parasitoid and hyperparasitoid species. Some chalcids could represent olive seed wasps (OSW), a generic term that designates the seed feeders responsible for losses in commercial olive production. In order to obtain direct DNA-based evidence for the lifestyle of four putative OSW-Eupelmus spermophilus Silvestri, Eurytoma oleae Silvestri, Eurytoma varicolor Silvestri, Sycophila aethiopica (Silvestri); and the parasitoid Neochrysocharis formosus (Westwood)-we developed a multiplex PCR assay comprising species-specific primers for each species. The assay was used to survey larvae collected from the seeds of wild and cultivated olives. Eupelmus spermophilus was the most abundant species in wild and cultivated olives, and may represent a threat to the local olive industry. Eurytoma oleae was found only within the seeds of wild olives, and may also represent an OSW. We found direct evidence supporting the potential agricultural relevance of S. aethiopica and E. varicolor as parasitoids of E. spermophilus. These results may inform strategies for the management and control of OSW in the Western Cape
Mitogenomics of the Olive Seed Weevil, Anchonocranus oleae Marshall and Implications for Its Phylogenetic Position in Curculionidae
Full text linkAnchonocranus oleae Marshall (Coleoptera: Curculionidae) is a seed-feeding weevil native to southern Africa; its larvae are known to develop in the fruits of the African Wild Olive and, more rarely, cultivated olives. The species has been mainly found in the Western Cape province of South Africa, but it has remained in relative obscurity because it does not seem to represent a current threat to commercial olive production. As part of an ongoing effort to produce baseline genetic data for olive-associated entomofauna in South Africa, we generated reference DNA barcodes for A. oleae collected from wild and cultivated olives and sequenced its mitogenome for assessment of the phylogenetic position of the species in the family Curculionidae. The mitochondrial phylogeny estimate indicated that A. oleae shares a common ancestor with Elaidobius (tribe Derelomini), but a definite and close relationship to this tribe and the precise tribal placement of A. oleae in the subfamily Curculioninae could not be inferred due to the lack of representative mitogenomes of other relevant curculionine tribes and genera. This study will assist future work on the DNA-based species identification, genetic diversity, and phylogenetic position of the genus Anchonocranus and related taxa
Olive Seed Wasp in Cultivated Olives. Possible threat.
No full textThe possible threat to cultivated olives due to some Chalcidoidea seed wasps are here highlighted, showing symptoms, identification and seasonal occurrenc
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
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