On the presence and distribution of olive viruses in Lebanon

A survey for viruses was carried out in 2003 in the main olive-growing areas of Lebanon (South Lebanon, North Lebanon, Mount Lebanon and Bekaa). A total of 300 samples was collected in 31 different locations in 76 different commercial orchards and checked by RT-PCR for the presence of Arabis mosaic virus (ArMV), Cherry leaf roll virus (CLRV), Strawberry latent ringspot virus (SLRV), Olive latent virus 1 (OLV-1) and Olive leaf yellowing-associated virus (OLYaV), using virus-specific primers reported in the literature. About one third (31%) of the trees were infected. In particular, the closterovirus OLYaV was the most widespread, as it was detected in 23.7% of the samples, followed by the necrovirus OLV-1 (8.3%), the two nepoviruses CLRV (2%) and ArMV (0.3%), and the sadwavirus SLRV (0.3%). A high variability was detected in the HSP70 gene of Lebanese and Italian OLYaV isolates, for at least nine different patterns were obtained when this genomic region was subjected to single-strand conformation polymorphism (SSCP) analysis.     

A novel approach to spider mite control based on expression of sarcotoxin IA peptidevia a virus-vector system in plants

Control of the spider miteTetranychus cinnabarinus Boisduval is problematic, and there is a pressing need for efficient, non-hazardous and inexpensive strategies for limiting the damage it causes. The gene for the anti-bacterial peptide sarcotoxin IA of the flesh flySarcophaga peregrina was cloned into the nonpathogenic potyvirus-based vector system ZYMV-AGII (Zucchini yellow mosaic virus-AGII). Expression of this peptidevia the AGII vector was detected in infected squash leaves and was not deleterious to the host plant. Leaf discs of squash infected with the recombinant virus AGII-sarcotoxin IA were tested for spider mite control under laboratory conditions. Spider mite egg production on plants expressing the sarcotoxin IA gene was decreased by a factor of two or three compared with that on AGII-infected plants or healthy leaf discs, respectively. In contrast to its effect on oviposition, sarcotoxin IA expressing squash did not significantly affect the mortality and the ability to repel spider mites. Crude extract from squash leaves infected with AGII-sarcotoxin IA was also found to cause a significant decrease of mite fecundity compared with extracts from AGII-treated or healthy plants and also caused a rise in mite mortality. Our results demonstrate that sarcotoxin IA affects mite fecundity and, to a lesser degree, mortality, and shows potential for controlling spider mites in the field.     

Field and laboratory experiments on the response and development of resistance to pesticides and population density ofTetranychus cinnabarinus in ISRAEL

Dosage mortality data for 12 pesticides were determined with females of an insecticide-susceptible strain of the carmine spider mite,Tetranychus cinnabarinus (Boisd.), by the slide dip method; for four of the pesticides which are specific acaricides, also the Munger cell method was used. The LC₅₀s ranged from 0.00078% to 0.041%, with the synthetic pyrethroids being more toxic than the specific acaricides. There were no differences in results between the two assay methods. Four synthetic pyrethroids that were very active againstT. cinnabarinus in laboratory tests were examined in an unsprayed apple orchard for their effect on the population density of spider mites. An upsurge of tetranychid mites was noted 4 weeks after a single application     

Toxicity of neem (Azadirachta Indica) seed kernel extracts prepared with different solvents,on the spider chiracanthium mildei

The toxicity of neem seed kernel extracts prepared with different solvents against the predatory spider,Chiracanthium mildei L. Koch, was investigated. The order of toxicity of the 4% extracts was pentane < acetone < ethanol << methanol = water (nontoxic). All extracts were nontoxic at 2.5%.     

Medicinal plant diversity in the flora of Saudi Arabia 1: a report on seven plant families

A preliminary survey on the medicinal plant diversity in the flora of the Kingdom of Saudi Arabia has been made with seven families: Amaranthaceae, Apocynaceae, Capparidaceae, Euphorbiaceae, Labiatae, Polygonaceae and Solanaceae, as an initial study. These families are represented in the flora with 254 species (i.e. 12% of the total species), and individually with 21, 7, 29, 66, 76, 22 and 33 species, respectively. Of these, 86 species, so far investigated, are medicinal, distributed in these seven families as follows: 7, 5, 12, 20, 23, 7 and 12, respectively. The Labiatae have the highest number (23) of medicinal plants among them while maximum medicinal plant diversity within the family has been observed with the Apocynaceae. An enumeration of these 86 medicinal species is presented with the current nomenclature, Arabic names and medicinal uses. This communication aims at emphasizing the importance of setting up conservation priorities, and sustained development of various medicinal plants of Saudi Arabia.     

In vitro assessment of the antimicrobial efficacy of chitosan nanoparticles against major fish pathogens and their cytotoxicity to fish cell lines

Nanotechnology is an emerging avenue employed in disease prevention and treatment. This study evaluated the antimicrobial efficacy of chitosan nanoparticles (CSNPs) against major bacterial and oomycete fish pathogens in comparison with chitosan suspension. Initially, the minimum inhibitory concentrations (MIC, MIC₉₀) were determined and the per cent inhibition of bacterial growth was calculated. Subsequently, the minimum bactericidal concentrations (MBCs) were determined. The time-dependent disruptions of CSNP-treated pathogens were observed via transmission electron microscopy (TEM), and the effect of CSNPs on the viability of two fish cell lines was assessed. No antimicrobial effect was observed with chitosan, while CSNPs (105 nm) exhibited a dose-dependent and species-specific antimicrobial properties. They were bactericidal against seven bacterial isolates recording MBC values from 1 to 7 mg/ml, bacteriostatic against four further isolates recording MIC values from 0.125 to 5 mg/ml and fungistatic against oomycetes recording MIC₉₀ values of 3 and 4 mg/ml. TEM micrographs showed the attachment of CSNPs to the pathogenic cell membranes disrupting their integrity. No significant cytotoxicity was observed using 1 mg/ml CSNPs, while low dose-dependent cytotoxicity was elicited by the higher doses. Therefore, it is anticipated that CSNPs are able to compete and reduce using antibiotics in aquaculture.     

Antibiosis of maize inbred lines to the carmine spider mite, tetranychus cinnabarinus

The antibiosis of tenZea mays L. inbred lines to the carmine spider mite,Tetranychus cinnabarinus (Boisduval) (Acari: Tetranychidae), was evaluated. Two maize inbred lines previously reported as resistant to this spider mite and a susceptible inbred line were compared with B96 (formerly called 41:2504B), reported as being resistant to the two-spotted spider mite T. urticae and to the European corn borer (Ostrinia nubilalis Hübner). Other lines were derived from B96. All lines originated in the U.S.A. and were tested in Israel at two different growth stages. Four days after inoculation of detached leaf squares with adult mites, significant differences in susceptibility were observed among lines. At the 3-leaf stage lines B68, B96, B79, A619, B65, B49 and B64 reduced the average mite daily fecundity by 43%, 64%, 66%, 67%, 77%, 81% and 87%, respectively, as compared with the most susceptible line, B52. At the flowering stage, the average reduction in mite daily fecundity was much lower: inbred lines B64, A619 and B96 reduced the average mite daily fecundity by 48%, 51% and 86%, respectively, whereas the seven other genotypes had an intermediate or a susceptible reaction to the carmine spider mite, with A661 being the most susceptible. Our results show that B96 could be used as a source of resistance in developing improved resistance of inbred lines of maize to carmine spider mites.     

Effects of deoxynivalenol exposure time and contamination levels on rainbow trout

The trend toward using plant‐based ingredients in aquafeeds is set to intensify; however, mycotoxin contamination might be a challenge. Two diets, with deoxynivalenol (DON) levels of 1,166 μg/kg (1.1 DON) and 2,745 μg/kg (2.7 DON), were prepared for short‐term DON exposure (50 days). A third diet with a low DON level of 367 μg/kg (0.3 DON) was prepared for long‐term DON exposure (168 days). Ingestion of DON by trout during both short‐term/high‐dosage exposure (50 days; 1,166 μg/kg and 2,700 μg/kg DON) and long‐term/low‐dosage exposure (168 days; 367 μg/kg DON) impacted growth performance and, to a lesser extent, liver enzyme parameters (2.7 DON). Histopathology showed mild to moderate changes in the liver but not in the other sampled tissues (intestine and kidney). Despite these effects, short‐term exposure of rainbow trout to high doses of DON did not result in increased susceptibility to Yersinia ruckeri. In both the short‐ and long‐term studies, the effects of DON showed a high interindividual variability. The present study confirms that subclinical levels of mycotoxins affect rainbow trout. The effects of such low mycotoxin levels could be masked by other production challenges while still negatively affecting productivity.     

Biodegradability Improvement of Sulfamethazine Solutions by Means of an electro-Fenton Process

The main objective of this study was to examine the effect of an electro-Fenton pretreatment on the biodegradability of sulfamethazine-polluted solutions. The aim of the pretreatment was only to degrade this molecule in order to increase the biodegradability of the effluent and therefore allow a subsequent biological treatment. Preliminary tests showed the absence of biodegradability of the target compound. The degradation of sulfamethazine by electro-Fenton process was then examined using a carbon felt cathode and a platinum anode in an electrochemical reactor containing 1?L of solution. The influence of some experimental parameters such as initial concentration, temperature and current intensity on the degradation by electro-Fenton step has been investigated. In addition, the biodegradability of the solution after electrochemical pretreatment was examined and showed a Biological Oxygen Demand (BOD₅) on Chemical Oxygen Demand (COD) ratio above the limit of biodegradability, namely 0.4, for several experimental conditions. The feasibility of coupling an electro-Fenton pretreatment with a biological degradation of by-products in order to mineralize polluted solutions of sulfamethazine was confirmed.