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For Tunisian olive tree orchards, nitrogen deficiency is an important nutritional problem, in addition to the availability of water. Establishment of relationships between nutrients such as nitrogen and ecophysiological parameters is a promising method to manage fertilisation at orchard level. Therefore, a nitrogen stress experiment with one-year-old olive trees (Olea europaea L. 'Koroneiki' and 'Meski') was conducted with trees respectively subjected to four nitrogen supply regimes (23.96 meq l(-1), 9.58 meq l(-1), 4.79 meq l(-1) and 0 meq l(-1) NO(3)(-)). The current paper focuses on the use of the SPAD-502 portable chlorophyll (Chl) meter, a nondestructive method for fertilisation management under nitrogen stress conditions of olive trees. Maximum net photosynthetic assimilation rates, chlorophyll fluorescence parameters and the SPAD Chl index were therefore measured simultaneously and the Chl and nitrogen content of the leaves were analysed. Significant correlations were established in the olive tree leaves between SPAD-502 readings on the one hand and Chl content, nitrogen content, photosynthetic assimilation rate, and Chl fluorescence parameters (Phi(PSII) and ETR) on the other hand

The migratory locust, Locusta migratoria (Linnaeus), is the most widespread locust species. Frequent applications of insecticides have inevitably resulted in environmental pollution and development of resistance in some natural populations of the locust. To find a new and safe alternative to conventional insecticides, experiments were conducted to assess the effect of olive leaf extracts on L. migratoria fifth instar larvae. The methanolic extracts were prepared from the leaves sampled during four phenological growth stages of olive tree which are as follows: Cluster formation (Cf), Swelling inflorescence buds (Sib), Full flowering (Ff), and Endocarp hardening (Eh). The most relevant result was noted with the extract prepared from the leaves collected at the Sib-stage. Results showed that treatment of newly emerged larvae resulted in a significant mortality with a dose-response relationship. The olive leaf extracts toxicity was also demonstrated by histopathological changes in the alimentary canal resulting in a considerable disorganization and serious damage of the midgut, ceca, and proventriculus structure. Epithelial cells alterations, less dense and degraded striated border, disintegrated regeneration crypts, vacuolarized cells, extrusion of cytoplasmic contents, and rupture of muscular layer were evident in the midgut and ceca of treated larvae. Data of biochemical analyzes showed that olive leaf extracts induced a significant decrease of the hemolymph metabolites (proteins, carbohydrates, and lipids). In a second series of experiments, we showed that the olive leaf extracts reduced the activity of acetylcholinesterase and induced the glutathione S-transferases with a dose-response relationship.

Effects of nitrogen (N) deficiency on photosynthetic carbon dioxide (CO 2 ) assimilation, photosystem II (PSII) photochemistry and photoinhibition were investigated in young trees of two olive cultivars 'Meski' and 'Koroneiki' grown in a greenhouse under controlled conditions. The trees were subjected to four different levels of N supply. N deficient trees had a significantly smaller CO 2 assimilatory capacity, but showed little changes in maximum quantum efficiency of Downloaded by [New York University] at 14:50 28 July 2015 ACCEPTED MANUSCRIPT ACCEPTED MANUSCRIPT 2 PSII photochemistry. However, modifications in PSII photochemistry induced by N deficiency were observed. This was reflected in decreases in quantum yield of PSII electron transport (Φ PSII )and efficiency of excitation energy capture by open PSII reaction centres (F v '/F m ') and in an increase in non-photochemical quenching (NPQ). These results suggest that modifications in PSII photochemistry might be a mechanism to down-regulate photosynthetic electron transport so that production of adenosine triphosphate (ATP) and nicotinamide adenine dinucleotide phosphate (NADPH). would be in equilibrium with the decreased demand in the Calvin cycle in the N deficient trees. Therefore, both CO 2 assimilation rate and total electron flow (J t ) with its compound electron flows devoted to either carboxylation (J c ) or oxygenation (J o ) can be considered as useful tools to assess the N nutrition status of the trees. Clear relationships were found between A max and the nitrogen nutrition index (NNI) on the one hand, and between J t and NNI on the other hand. The results demonstrate that 'Meski' is more efficient than 'Koroneiki' when subjected to N deficiency.

The effects of olive leaf extract (OLE) are studied on several reproductive variables and the ovarian biochemical composition of Locusta migratoria (Orthoptera: Acrididae) adult females. The methanolic extracts are prepared from the leaves sampled during four phenological growth stages of olive tree: cluster formation (Cf), swelling inflorescence buds (Sib), full flowering (Ff) and endocarp hardening (Eh). When applied to adult females during the pre-ovipositional phase, the treatment elicites a significant adverse effect on their reproductive potential. Indeed, OLE significantly reduces both fecundity and fertility and affects oocyte growth during the first gonadotrophic cycle, as indicated by measurements of ovarian weight, length of terminal oocytes and ovarian index. Furthermore, OLE is examined with respect to ovarian biochemical components. Biochemical analyses reveal a significant reduction of ovarian contents of proteins, lipids and carbohydrates, suggesting a disruption in the incorporation of the haemolymph metabolites in the oocytes and an interference of OLE with the vitellogenesis process. The antigonadotrophic effect is confirmed by a histological study of the ovaries, which clearly shows a delay in ovarian development and in yolk accumulation in the basal oocytes of treated females. The most effect is noted with the extract prepared from the leaves collected at the swelling inflorescence buds for all measured parameters, which appears to be related to its high content of polyphenols. Acrididae) comprise the two major species. These species exhibit phenotypic plasticity, known as density-dependent phase polyphenism, where individuals can exist anywhere between two extreme forms (solitarious versus gregarious) that differ in their morphology, physiology, behaviour, ecology and propensity to cause agricultural damage (Lazar et al., 2016;Cullen et al., 2017). Locusts at the solitarious form cause little damage to agricultural crops but, in the gregarious phase, they are responsible for substantial damage to crops and grazing, as

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