Tests on the effectiveness of kaolin and copper hydroxide in the control of Bactrocera oleae (Gmelin)

Repellent and antiovipositional products in the control of Bactrocera oleae (Gmelin) find a great interest in organic farming, because of the lack of effective products able to kill the olive fly preimmaginal stages. In 2003 in Castelvetrano (Trapani province, Sicily), tests on the effectiveness of Surround WP, a product containing 95% of kaolin, were carried out on three table olive cultivars, Nocellara del Belice, Moresca and Tonda Iblea. In 2004, in the same field and on the same cultivars, BPLK kaolin was tested too. In the second year the two products containing kaolin were also tested on Cerasuola cultivar in an organic olive grove located in Trapani, comparing them with copper hydroxide. At Castelvetrano both in 2003 and in 2004 B. oleae infestation levels of the plots treated with the two products containing kaolin were statistically lower than those of the control plots. In this site, in 2004 Surround WP protected olives significantly better than BPLK kaolin, limiting olive fly harmful infestation up to 17-23% vs. 68-87% of BPLK plots. At Trapani in 2004, the two products containing kaolin and copper hydroxide showed statistically significant differences from the untreated control, but not among themselves, limiting the harmful infestation up to 3-37% vs. 87% of the control. The different results of 2004 recorded by Surround WP and BPLK kaolin in the two olive groves seems linked to the different rainfall of the period after the last treatment, 64 mm in three rainy days at Castelvetrano and 41 mm in eight rainy days at Trapani; BPLK kaolin was probably washed away more than Surround WP. The tested products containing kaolin and copper hydroxide are effectively able to limit B. oleae infestation to a very good level for olive oil production, moreover, considering the earlier harvesting of table olives, these products give a new opportunity for controlling the olive fly also in the organic olive groves for table olive production

Resistance to the attack of Bactrocera oleae (Gmelin) of some Sicilian olive cultivars

Genetic resistance of olive germplasm could be an important tool in the control of Bactrocera oleae (Gmelin), the key pest in the Mediterranean olive growing. Up to now, no study was carried out on olive cultivars stressed a complete resistance to the attack of B. oleae, and few scientific data are available on susceptibility to olive fruit fly of Sicilian cultivars, although differences among susceptibility of cultivars could be usefully considered to obtain quality productions and to reduce insecticides use both in organic and conventional olive growing. The present study was carried out at Castelvetrano (Trapani province, Sicily), in the olive germplasm collection of Ente di Sviluppo Agricolo of the Sicilian Region and Dipartimento di Colture Arboree of the University of Palermo. From 2002 to 2005, infestation levels in drupes of 18 cv, representing the most widely cultivated in Sicily was recorded. Samplings were carried out every 11-20 days, starting from the second half of August to the end of October. Moreover, from 2003 to 2005 infestation levels were correlated with size and hardness of olives, while in 2004-2005 data on olive coloration were collected at different ripening stages. Among the cultivars producing larger olives, Nocellara del Belice resulted the most susceptible to the olive fruit fly attacks, while Nocellara messinese was the less infested one. Among cultivars with medium, small-sized fruits Moresca, Vaddarica, Nasitana frutto grosso, Minuta and Bottone di gallo were the less susceptible ones. Among the tested cultivars Nocellara del Belice was the most attacked one in every year of the research. A positive correlation between infestation and olive size was found, resulting in higher infestation levels on the cultivars producing larger olives. B. oleae showed a clear preference for green drupes, instead of reddish or blackish ones. In two out of three years a negative correlation between hardness and infestation was found in September

Notizie: L’Istituto Tecnico Industriale “A. Volta” di Trieste primo nel concorso nazionale del Piano nazionale Lauree Scientifiche

Fondazione CRTriest

Book review: Malaysian Christians online: faith, experience, and social engagement on the internet by Meng Yoe Tan

In Malaysian Christians Online: Faith, Experience, and Social Engagement on the Internet, Meng Yoe Tan explores how the internet has provided an environment for Malaysian Christians to articulate personal engagement with the faith. This book stands out as a vivid ethnography of the way cyberspace is mobilised by minority religious groups, writes Roberto Rizzo. This book review is published by the LSE Southeast Asia blog and LSE Review of Books blog as part of a collaborative series focusing on timely and important social science books from and about Southeast Asia. Malaysian Christians Online: Faith, Experience, and Social Engagement on the Internet. Meng Yoe Tan. Springer. 2020

Soglie di dannosità e strategie di controllo di Bactrocera oleae (Rossi) nell'olivicoltura biologica da tavola

Olive fly control is the main limit to the diffusion of organic table olives production, because of the lack of effective larvicides. Few studies on damages in table olives due to B. oleae and on applied damage thresholds are recorded. Results of this research show that sterile and fertile olive fly punctures are no more detectable by the naked eye on the surface of processed table olives; on the contrary exit holes are still clearly visible and affect the appearance of olives. Damage threshold applied before sizing and selection by processors of Nocellara del Belice cultivar ignores punctures and consists of 10% of 3rd instar larvae or 5% of exit holes; after sizing and selection exit holes threshold lowers to 1%. Our tests on olive fly control in organic table olive production suggest that early ripening cultivars, less susceptible cultivars, an orchard management able to reach olive size early, a low olive fly pressure (because of the year or local conditions) allow to maintain table olives below the damage threshold; one to three sprays with clays and copper products, particularly kaolin and copper hydroxide, in most cases resulted in an effective reduction of B. oleae attacks

Strategie di controllo di Bactrocera oleae (Rossi) nell’olivicoltura biologica da olio e da tavola.

I buoni risultati ottenuti nell’olivicoltura biologica da olio sono legati alla raccolta anticipata che limita le infestazioni tardive di Bactrocera oleae (Rossi) e gli effetti negativi delle infestazioni in atto. Molto utilizzate per il controllo della mosca sono le catture massali. L’infestazione dannosa registrata nei due mesi precedenti la raccolta risulta strettamente correlata alla qualità dell’olio, mentre non lo è l’infestazione totale alla raccolta. Gli insetticidi consentiti nell’olivicoltura biologica sono molto poco utilizzati. Nelle situazioni di forte pressione della mosca soltanto i trattamenti con argille e prodotti del rame riescono a mantenere bassi i livelli d’infestazione. L’attenta gestione dell’oliveto nella produzione di olive da tavola è importante per ottenere precocemente adeguate pezzature dei frutti. Le sole punture di ovideposizione si sono dimostrate poco o per nulla visibili ad occhio nudo sulle olive trasformate e non ne compromettono l’estetica

Motility fractionation of bacteria by centrifugation

Centrifugation is a widespread laboratory technique used to separate mixtures into fractions characterized by a specific size, weight or density. We demonstrate that centrifugation can be also used to separate swimming cells having different motility. To do this we study self-propelled bacteria under the influence of an external centrifugal field. Using dynamic image correlation spectroscopy we measure the spatially resolved motility of bacteria after centrifugation. A significant gradient in swimming-speeds is observed for increasing centrifugal speeds. Our results can be reproduced by a model that treats bacteria as "hot" colloidal particles having a diffusion coefficient that depends on the swimming speed.Comment: 7 pages, 5 figures (in press