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Khemira S.,French National Institute for Agricultural Research | Jemaa J.M.-B.,French National Institute for Agricultural Research | Haouel S.,French National Institute for Agricultural Research | Khouja M.L.,Institute National Of La Recherche En Genie Rural
Acta Horticulturae | Year: 2013

Insect pests cause serious losses in quantity and quality of the stored products during storage. The lesser grain borer, Rhyzopertha dominica F. (Coleoptera: Bostrichidae) and the sawtoothed grain beetle Oryzaephilus surinamensis L. (Coleoptera: Silvanidae) are considered as major insect pests in storage in Tunisia and worldwide. The excessive use of synthetic insecticides associated with intensification in agriculture lead to health and environmental problems. This situation requires efforts to find safe, effective and viable alternatives. Natural products are well known to have a range of useful biological properties against insect pests. Recently, research on insecticidal and repellent properties of essential oils has received attention for stored-product protection. Essential oils and extracts from genus Eucalyptus are well known to posses these properties. This study was initiated to evaluate the repellency action of Eucalyptus astringens essential oil against adults of O. surinamensis and R. dominica. Essential oil was extracted by hydrodistillation using Clevenger modified apparatus. GC/MS analysis showed that the main components were a-pinene (29.83%), 1,8-cineole (17.29%) and transpinocarveol (3.39%). E. astringens essential oil exhibited a repellent action against the two insects. At the concentration, 0.08 μl/m2, the repellency percentage was respectively 55% for O. surinamensis and 58.75% for R. dominica after 24 h of exposure.

Jemaa J.M.-B.,French National Institute for Agricultural Research | Tersim N.,French National Institute for Agricultural Research | Khouja M.L.,Institute National Of La Recherche En Genie Rural
Acta Horticulturae | Year: 2013

An increased interest has been employed in the research on natural products, including plant extracts, which might replace synthetic pesticides or contribute toward the development of new pest control agents. During the last decade, essential oils have been shown to possess a broad spectrum of insecticidal activity. The Laurel, Laurus nobilis L. (Lauraceae), commonly called 'Rand' is an evergreen tree up to 20 m high and native to the Mediterranean region. In Tunisia, it occurs and grows especially near river borders and mountains (region of Kroumirie, Ain Drahm, Tabarka and Kef). Some specimens are still encountered in the region of Zaghouan (Djebel Ghorra). It is generally used as a valuable spice and flavouring agent in the culinary and food industry. In traditional medicine, it is used as nerving against, hysteria and emmenagogue Powdered fruit in the form of infusion possesses diuretic and carminative properties. Besides, the repellent action of its essential oil was reported against several species of stored-product pests. The goal of this work was to investigate the repellency of essential oil extracted from fresh leaves of laurel Laurus nobilis (L.) against a major beetle of stored-product Lasioderma serricorne (F.). The cigarette beetle, Lasioderma serricorne is known to develop on a variety of grain-based products, spices and tobacco and infest these commodities during storage, and manufacturing. This is a major stored-product pest in Tunisia and North Africa. Results showed that L. nobilis essential oil was characterized by 1,8-cineole (24.55%), linalool (17.67%), eugenylmethylether (12.40%), isovaleraldehyde (9.65%) and camphene (7.21%) as major components. The repellent action depends on oil concentration. Repellent percentages were respectively 12.5, 57.5 and 60% at concentrations 0.04, 0.08 and 0.2 μl/cm2. Moreover, the lethal repellent dose 50 (RD50) was 37.84 μl/cm2.

Hanana M.,Center de Biotechnologie de la Technopole de Borj-Cedria | Hamrouni L.,Institute National Of La Recherche En Genie Rural | Cagnac O.,CSIC - Experimental Station of El Zaidín | Blumwald E.,University of California at Davis
Environmental Reviews | Year: 2011

The problem of salinity is multiple. In addition to salt stress, ion toxicity (Na+ and Cl- dissolved in irrigation water or in soil solution), and mineral nutrition perturbation, plants have difficulty absorbing water from soil because of its elevated osmotic pressure, which leads to water stress and thus complicates and impairs their physiological state in an exponential way. Consequently, cells try to adjust their water potential by ion homeostasis regulation via vacuolar compartmentation and (or) extrusion out of the cell of the toxic ions (Na+ and Cl-). Nevertheless, if this is not sufficient, the plant has to use another way to face salt stress, which consists in the synthesis and accumulation of a class of osmoprotective compounds known as compatible solutes, mainly amino compounds and sugars. Energetically, this osmotic strategy is more expensive than ion homeostasis regulation. A secondary aspect of salinity stress in plants is the stress-induced production of reactive oxygen species leading to an oxidative stress whose damage reduction could be realized via the production of antioxidants. Perception and signal mechanisms represent the first events of plant stress adaptation, and the main pathways followed are calcium, abscissic acid (ABA), mitogen-activated protein kinases (MAPKinases), salt overly sensitive (SOS) proteins, and ethylene. © 2011 Published by NRC Research Press.

Nasr Z.,Institute National Of La Recherche En Genie Rural | Khouja M.L.,Institute National Of La Recherche En Genie Rural | Aini R.,Ministery of Agriculture | Hammadi A.,Institute National Of La Recherche En Genie Rural | And 2 more authors.
Journal of Applied Horticulture | Year: 2013

Bio-diesel crops are presented as a potential tool to mitigate global warming. However, these crops are often highly water consuming, which limits their use in semi-arid areas. In this respect, the Jatropha is considered by many researchers as the most appropriate species in these dry conditions. The aim of our investigation was to study the possibility of its use in Tunisia regarding its behavior in semi-arid area of the north-west region. Eight provenances of Jatropha curcas L. introduced from Brazilia (5), Surinam (1), Mosambic (1) and Tanzania (1) were compared on the basis of their ecophysiological performance. Results showed variability in photosynthesis, leaf transpiration, chlorophyll content and leaf growth between accessions during the growing season. Average photosynthesis and leaf transpiration values ranged from 7 to 13 μmol m-2 s-1 and from 2.5 to 3.5 mmol m-2 s-1, respectively. Specific dry matter per unit leaf area varied from 50 g m-2 to 90 g m-2. Provenances from the Mozambic and Pranà with the lowest biomass per unit leaf area and high photosynthetic capacity are more likely to offer greater productivity in semi-arid zone.

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