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A study was carried out to demonstrate that Rice yellow mottle virus (RYMV), a virus known to be transmitted by beetles, can spread between rice plants by direct leaf contact caused by wind. Almost all healthy plants surrounding an infected plant became infected when exposed to a fan blowing for 15 min at a distance of 50 cm. Spread of RYMV by plant contact, mediated by wind, was also demonstrated in field experiments, the extent of spread depending on plant density. Infection was almost 10 times higher in plots with a density of 33 plants m−2 than in plots with 16 plants m−2 . Less spread was observed in plots protected by 1·5 m high windscreens. It is suggested that wind-mediated spread of RYMV may result from abrasive contact between leaves of plants. 相似文献
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Yassine Benzidane Sarra Touinsi Emilie Motte Alain Jadas‐Hécart Pierre‐Yves Communal Lionel Leduc Steeve H Thany 《Pest management science》2010,66(12):1351-1359
BACKROUND: In the present study, the effect of thiamethoxam and clothianidin on the locomotor activity of American cockroach, Periplaneta americana (L.), was evaluated. Because it has been proposed that thiamethoxam is metabolised to clothianidin, high‐performance liquid chromatography coupled with mass spectrometry was used to evaluate the amount of clothianidin on thiamethoxam‐treated cockroaches. RESULTS: One hour after neonicotinoid treatment, the time spent in the open‐field‐like apparatus significantly increased, suggesting a decrease in locomotor activity. The percentage of cockroaches displaying locomotor activity was significantly reduced 1 h after haemolymph application of 1 nmol g?1 neonicotinoid, while no significant effect was found after topical and oral administration. However, at 24 and 48 h, all neonicotinoids were able to reduce locomotor activity, depending on their concentrations and the way they were applied. Interestingly, it was found that thiamethoxam was converted to clothianidin 1 h after application, but the amount of clothianidin did not rise proportionately to thiamethoxam, especially after oral administration. CONCLUSION: The data suggest that the effect of thiamethoxam on cockroach locomotor activity is due in part to clothianidin action because (1) thiamethoxam levels remained persistent 48 h after application and (2) the amount of clothianidin in cockroach tissues was consistent with the toxicity of thiamethoxam. Copyright © 2010 Society of Chemical Industry 相似文献
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Hager Blel Noureddine Chatti Raouf Besbes Sarra Farjallah Ali Elouaer Hammadi Guerbej & Khaled Said 《Aquaculture Research》2008,39(3):268-275
The Mugilidae family is an important fish group representing a major source for fisheries and aquaculture. In the south Mediterranean bank, no data are available on this fauna, except for some morphological studies on Tunisian samples. In this study, 16 allozymic loci were used to investigate the phylogenetic relationships within Tunisian mugilids. The results obtained from Hergla lagoon samples highlight five operational taxonomic unit corresponding to the well‐known species (Liza aurata, Liza ramada, Liza saliens, Chelon labrosus, Mugil cephalus). Several loci appeared to be diagnostic of these species, but in contrast to Greek mugilid samples, we did not find any diagnostic locus fixed differently for the five species. These results can help aquaculture units to identify accurately the mullet species they subsequently use for stocking aquaculture ponds and inland waters. However, species identity represents very important information, as each species has a different growth rate and salinity tolerance. On the other hand, when compared with North Mediterranean Mugilidae analysed until now, Tunisian samples show a genetic differentiation that could be related to different physicochemical conditions between the North and South banks, similar to those recorded in the eastern and western two Mediterranean basins separated by the Siculo‐Tunisian strait. In addition, this study confirms the morphological taxonomy, except for the subdivision of the Liza genus into two sub‐genera. The phylogenetic tree is in agreement with that on Languedoc Mugilidae samples (France), indicating that the subdivision of the Liza genus into two sub‐genera appears to be without any genetic base. 相似文献
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Objective To determine the practicability and accuracy of central corneal thickness (CCT) measurements in living chicks utilizing a noncontact, high‐speed optical low‐coherence reflectometer (OLCR) mounted on a slit lamp. Animals studied Twelve male chicks (Gallus gallus domesticus). Procedures Measurements of CCT were obtained in triplicate in 24 eyes of twelve 1‐day‐old anaesthetized chicks using OLCR. Every single measurement taken by OLCR consisted of the average result of 20 scans obtained within seconds. Additionally, corneal thickness was determined histologically after immersion fixation in Karnovsky’s solution alone (20 eyes) or with a previous injection of the fixative into the anterior chamber before enucleation (4 eyes). Results Central corneal thickness measurements using OLCR in 1‐day‐old living chicks provide a rapid and feasible examination technique. Mean CCT measured with OLCR (189.7 ± 3.34 μm) was significantly lower than histological measurements (242.1 ± 47.27 μm) in eyes with fixation in Karnovsky’s solution (P = 0.0005). In eyes with additional injection of Karnovsky’s fixative into the anterior chamber, mean histologically determined CCT was 195.2 ± 8.25 μm vs. 191.9 ± 8.90 μm with OLCR. A trend for a lower variance was found compared to the eyes that had only been immersion fixed. Conclusion Optical low‐coherence reflectometry is an accurate examination technique to measure in vivo CCT in the eye of newborn chicks. The knowledge of the thickness of the chick cornea and the ability to obtain noninvasive, noncontact measurements of CCT in the living animal may be of interest for research and development of eye diseases in chick models. 相似文献
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During a survey carried out in August 2013 along all coastal areas of north-eastern Tunisia (governorships of Bizerte, Ariana, Tunis, Ben Arous, Nabeul, Sousse), eucalyptus trees were found to be highly infested by the invasive pest Glycaspis brimblecombei Moore, 1964, also known as red gum lerp psyllid. This insect, native to the Australian region and secondarily dispersed also in the Americas, Mauritius, Madagascar and South Africa, very recently started to invade the Mediterranean region and in almost 5 years has spread to the Iberian Peninsula, Italy, Greece and Morocco. Its presence in Tunisia (which is recorded here for the first time) most probably dates back to summer 2012, since typical necrotic spots caused by the lerp of the psyllid had already been noted on leaves during spring 2013. No presence of its main parasitoid – Psyllaephagus bliteus Riek – nor of any other natural enemy, was noted up to now during our survey in Tunisia. 相似文献
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Gnissa Konate Soungalo Sarra Oumar Traore 《European journal of plant pathology / European Foundation for Plant Pathology》2001,107(3):361-364
Seed transmission of two pathogroups of rice yellow mottle virus from Soudano-Sahelian areas of West Africa was studied in several rice genotypes. The virus was detected by enzyme-linked immunosorbent assay and the highly susceptible rice variety BG 90-2 was used for infectivity assays. In most of the rice genotypes studied (17 out of 21), rice yellow mottle virus was detected in all seed parts including glumella, endosperm and embryo at a rate ranging from 65 to 100%. Nevertheless, no seed-borne infection was found. Infectivity of the virus decreased throughout the process of seed formation suggesting inactivation of the virus as a result of seed maturation and desiccation. It was concluded that rice yellow mottle epidemics do not develop from seed-borne infections in rice seeds. 相似文献
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Olfa Dabbaghi Meriem Tekaya Naouraz M'barki Sarra Ouled ali Sevgi Öden Mouna Aïachi Mezghani 《Journal of plant nutrition》2013,36(18):2281-2297
Growth and biochemical parameters of leaves, flower buds and flowers of olive (Olea europaea L. cv. Chemlali) treated by foliar biofertilization (T0: untreated trees; T1: rich in nitrogen (N), phosphorus (P), potassium (K); T2: rich in calcium (Ca); T3: application of T1 and T2) were analyzed during the flowering stage. The results showed that T1 resulted in higher contents of leaf N, K, and Na. T1 and T3 resulted in an increase of pigment concentration in leaves. All foliar treatments affected negatively the contents of total polyphenols and orthodiphenols in leaves and flower buds. Lower amounts of individual phenolic compounds were detected in the leaves under all foliar bio-fertilizations and in flower buds of olive trees sprayed with T2 and T3. This decrease is explained by the lower enzymatic activity of l-phenylalanine ammonia-lyase. In flowers, T1 exhibits the highest levels of total polyphenols, o-diphenols, and individual phenolic compounds compared to T0. 相似文献
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Sarra Bouagga Alberto Urbaneja José L. Rambla Antonio Granell Meritxell Pérez-Hedo 《Journal of pest science》2018,91(1):55-64
Orius laevigatus is a generalist predator that is widely used in augmentative strategies against the key pest of sweet pepper, Frankliniella occidentalis. Despite being a zoophytophagous predator, the phytophagous behavior of O. laevigatus has not been previously explored in depth nor has the impact of phytophagy on plant physiology. Here, the hierarchical significance of O. laevigatus feeding on sweet pepper is compared with other behaviors. O. laevigatus spends the majority of its time (38%) feeding on apical meristems and apical fresh leaves, which were also preferred residence locations. Here, the phytophagous feeding behavior of O. laevigatus on sweet pepper is shown to trigger defensive responses in the plant. These O. laevigatus plant-induced defenses are then shown to contribute to the repellence or attraction of pests or natural enemies, respectively. Specifically, O. laevigatus-punctured sweet pepper plants induce repellency for the whitefly Bemisia tabaci and the thrips species F. occidentalis. In contrast, the whitefly parasitoid Encarsia formosa was significantly attracted to O. laevigatus-punctured plants. The plant responses to O. laevigatus punctures include the release of an altered blend of volatiles and activation of the jasmonic acid and salicylic acid signalling pathways. These results highlight an interesting facet to the biology of O. laevigatus, in which the ability of the predator to induce defensive responses in sweet pepper plants may serve to improve the biological control of both thrips and whiteflies. 相似文献