Northwestern Tunisia Research Articles

Estimating Forest Fire Losses Using Stochastic Approach: Case Study of the Kroumiria Mountains (Northwestern Tunisia)

ABSTRACT Kroumiria Mountains (northwestern Tunisia) have experienced major fires, making them the main loss reason of Tunisian forested areas. The ability of accurately forecasting or modeling forest fire areas may significantly aid optimizing fire-fighting strategies. However, there are still limitations in the empirical study of forest fire loss estimation because the poor availability and low quality of fire data. In this study, a stochastic approach based on Markov process was developed for the prediction of burned areas, using available meteorological data sets and GIS layers related to the forest under analysis. The Self-organizing map (SOM) was initially used to classify spatiotemporal factors influencing the fire behavior. Subsequently, the SOM clusters were incorporated into a Hidden Markov Model (HMM) framework to model their corresponding burned areas. Results achieved using a database of 829 forest fires records between 1985 and 2016, showed the appropriateness of the HMM approach for the prediction of burned areas compared with a state-of-the art machine learning methods. The transition probability matrix (TPM) and the emission probability matrix (EPM) were also analyzed to further understand the spatiotemporal patterns of fire losses.

Parasitoids of chickpea leafminer Liriomyza cicerina (Diptera: Agromyzidae) and their parasitism rate on chickpea fields in North Tunisia

Abstract In recent years, as a consequence of climatic changes, the leafminer Liriomyza cicerina had emerged as a serious pest in chickpea crops causing considerable damage in Tunisia. Thus, the search of control methods is necessary. The aim of this research was to monitor and identify the naturally occurring parasitoids of the chickpea leafminer Liriomyza cicerina in insecticide-free chickpea-growing areas located in North-Western Tunisia. Chickpea leaves with mines were weekly sampled from Beja and Kef sites during 2016 and 2017 and kept to observe and count emerging leafminer and parasitoid adults in the laboratory. Results revealed that L. cicerina parasitoids complex species included three hymenopteran parasitoids namely Opius monilicornis (Fisher, 1962) (Braconidae); Diglyphus isaea (Walker, 1838) (Eulophidae) and Diaulinopsis arenaria (Erdos, 1951) (Eulophidae). These parasitoids were identified and recorded for the first time in Tunisia on L. cicerina with parasitism rate varied between 13% and 52.5%. The most common species was O. monilicornis. The correlation between infestation rate on chickpea plants and number of emerged three parasitoids was calculated revealing high significant and positive correlations. The diversity index (H′) was also calculated. The three parasitoids were found in two sites Beja and Kef; while the diversity differed during the developmental stage of chickpea crops.

Hydro-geophysical and geochemical studies of the aquifer systems in El Kef region (Northwestern Tunisia)

In El Kef region, Northwestern Tunisia, the evolution of the agricultural and industrial sectors has exacerbated the need for water which caused a significant increase in groundwater extraction. In this context, several geologic and geophysical studies conducted on the groundwater resources of the concerning area were meant to give us insight into the geometry of the reservoirs and structural architecture of the basin and to identify the various reservoirs such as the Mio-Plio-Quaternary, the Lower Eocene and the Campanian–Maastrichtian aquifers. In this study, we used the geochemical study and analysis of gravity data (Horizontal and vertical derivative, horizontal gravity gradient maxima…) to improve the knowledge of the dip and direction fault and the geological structures in El Kef region (NW Tunisia) that control the groundwater hydrodynamic. Furthermore, the techniques of horizontal gradient and upward extension were applied to determine the gravity lineaments that represent the location of density contrasts and to locate the various faults that contribute to the structuring of the study area. Additionally, this study aims to assess the spatio-temporal evolution of the hydrodynamic parameters of the aquifers and to characterize the groundwater mineralization (salinity, chemical facies relationship, etc.). Our study showed the presence of four types of water facies: Ca–Mg–SO4; Na–Cl–NO3; Ca–Mg–HCO3 and Na–K–HCO3. The isotopic study is used to provide some information about the groundwater recharge and to define the different sources of water mixing. That way we could have better understanding to the hydrologic cycle and to the paleoclimate of the study area. Generally, the geochemically evolved groundwaters of the aquifer systems of El Kef region are relatively isotopically depleted when compared to the present day meteoric waters reflecting recharge under cold climate and high altitude. Conversely, the continuous increase of the annual mean temperature and the decrease of precipitations have been observed for the second half of the 20th century in North Africa. It is likely related to the warmer and drier conditions associated with the climate change phenomenon.

Natural Hematite and Siderite as Heterogeneous Catalysts for an Effective Degradation of 4-Chlorophenol via Photo-Fenton Process

This paper describes a simple and low-cost process for the degradation of 4-Chlorophenol (4-CP) from aqueous solution, using natural Tunisian Hematite (M1) and Siderite (M2). Two natural samples were collected in the outcroppings of the Djerissa mining site (Kef district, northwestern Tunisia). Both Hematite and Siderite ferrous samples were characterized using several techniques, including X-Ray Diffraction (XRD), Nitrogen Physisorption (BET), Infrared Spectroscopy (FTIR), H2-Temperature Programmed Reduction (H2-TPR), Scanning Electronic Microscopy (SEM) linked with Energy Dispersive X-ray (EDS) and High-Resolution Transmission Electron Microscopy (HRTEM). Textural, structural and chemical characterization confirmed the presence of Hematite and Siderite phases with a high amount of iron on the both surface materials. Their activity was evaluated in the oxidation of 4-CP in aqueous medium under heterogeneous photo-Fenton process. Siderite exhibited higher photocatalytic oxidation activity than Hematite at pH 3. The experimental results also showed that 100% conversion of 4-CP and 54% TOC removal can be achieved using Siderite as catalyst. Negligible metal leaching and catalyst reutilization without any loss of activity point towards an excellent catalytic stability for both natural catalysts.

Preliminary structural configuration of the Goubellat Upper Cretaceous carbonate aquifers using gravity method (Northwestern Tunisia)

Gravity method can help locate hidden structural blocks bounded by faults related to the Upper Cretaceous carbonate aquifers of Goubellat region (Northwestern Tunisia). The Quaternary deposits are present over the majority of the Goubellat plain basin and cover the Upper Cretaceous carbonate. The produced residual gravity map supported by vertical and tilt angle derivatives was used to reveal the subsurface structural framework of the study area shaped by uplifted (high gravity anomalies) and downlifted areas (low gravity anomalies). The horizontal gravity gradient and Euler deconvolution maps were elaborated in order to locate major faults. These faults are primordial for the subsurface water recharge pathways. Finally, the presented lineament/structural map is very useful for large-scale structures and lineaments mapping giving the principal keys of the preliminary structural configuration of the Goubellat Upper Cretaceous carbonate aquifers.

Statistical and geochemical assessment of groundwater quality in Teboursouk area (Northwestern Tunisian Atlas)

Teboursouk region, Northwestern Tunisia, is characterized by the diversity of its natural resources (petroleum, groundwater and minerals). It constitutes a particular site widely studied, especially from a tectonic stand point as it exhibits a complex architecture dominated by multi-scale synclinals and Triassic extrusions. It has typical karst landform that constitutes important water resources devoted for human consumption and agriculture activities, besides to the exploitation of the Mio-Plio-Quaternary aquifer (MPQ). Thus, hydrogeological investigations play a significant role in the assessment of groundwater mineralization and the evaluation of the used water quality for different purposes. Hence, the current study based on a combined geochemical–statistical investigation of 50 groundwater samples from the multilayered aquifer system in the study area give crucial information about the principal factors and processes influencing groundwater chemistry. The chemical analysis of the water samples showed that Teboursouk groundwater is dominantly of Ca–Mg–Cl–SO4 water type with little contribution of Ca–Mg–HCO3, Na–K–Cl–SO4 and Na–K–HCO3. The total dissolved solids (TDS) values range from 0.37 to 3.58 g/l. The highest values are located near the Triassic outcrops. Furthermore, the hydrogeochemistry of the studied system was linked with various processes such as carbonates weathering, evaporites dissolution of Triassic outcrops and anthropogenic activities (nitrate contamination). Additionally, the main processes controlling Teboursouk water system were examined by means of multivariate statistical analysis (PCA and HCA) applied in this study based on 10 physicochemical parameters (TDS, pH, SO4, HCO3, pCO2, Ca, Mg, Na, K, Cl and NO3). Two principal components were extracted from PCA accounting 61% of total variance and revealing that the chemical characteristics of groundwater in the region were acquired through carbonates and evaporite dissolution besides to nitrate contamination. Similarly, according to Cluster analysis using Ward’s method and squared Euclidean distance, groundwater from the studied basin belongs to five different groups suggesting that the geochemical evolution of Teboursouk groundwater is controlled by dissolution of carbonates minerals, chemical weathering of Triassic evaporite outcrops, cation exchange and anthropogenic activities (nitrate contamination).

Potential use of the lower cretaceous clay (Kef area, Northwestern Tunisia) as raw material to supply ceramic industry

Abstract The aim of this study is to evaluate the potential use of clay deposits from northern Tunisia (Albian system) for the manufacture of bricks and ceramic tiles. Clay samples were collected from the Slata study site to the north of the Kef district, Tunisia. Chemical composition by atomic absorption spectrometry (AAS) showed that these clays were mainly composed of silica (33%), alumina (15%), iron oxide (6%) and minor amount of potassium oxide (3%). Mineralogical analysis by X-ray diffraction (XRD) confirmed the results of AAS; it showed reflections of quartz, calcite, kaolinite (65–70%) and illite (15%) associated with low percentage of interstratified illite-smectite (5%). After firing near 900 °C, new mineralogical species such as mullite, anortite and spinel appeared due to several temperature-dependent transformations. Further analysis indicated that plasticity index (PI) ranged between 16 and 20%. Geotechnical and thermal tests have shown acceptable values of drying shrinkage (3%), firing shrinkage (10%), water absorption (8.9–15.9%) and a very high mechanical bending strength (17–20 MPa) indicating non-refractory clays. Those results further confirmed the potential application of the Albian clays from Slata site in ceramics.

Influence of mulching and tree shelters on 4-year survival and growth of zeen oak (Quercus canariensis) seedlings

We assessed the effect of mulching and tree shelters on the establishment and early growth of zeen oak (Quercus canariensis Willd.) during the first 4 years after planting in Northwestern Tunisia. Five mulch types (Italian Stone Pine (Pinus pinea L.), Lentisk (Pistacia lentiscus L.), and a combination of Italian Stone Pine and Lentisk (organic mulches), gravel (inorganic mulch) and control), and three tree shelter types (non-vented and vented tree shelters, and control) were tested. An increase in the number of internodes occurred under the gravel mulch, while a reduction in survival was found for the lentisk mulch. Tree shelters had no effect on survival, but increased mean height growth and reduced mean diameter growth during the 4 years (excepting a non-significant effect for vented tree shelter at year four). Comparison of the annual shoots and growth units (GU) between sheltered and unsheltered plants according to year of formation revealed two growth phases. In first phase, shoots were totally or partially inside the shelters; mean length of annual shoots and GU were greater for sheltered plants. The second phase was characterized by shoots emerging from shelters; mean length of annual shoots and GU were similar for all plants, with or without tree shelters. Results suggest that the use of tree shelters, particularly vented shelters, could contribute to the improvement of the artificial regeneration of zeen oak. The use of mulching alone or in combination with tree shelters did not improve zeen oak performance in the field.

Influence de l’état sanitaire des glands sur la régénération de Quercus suberen Tunisie

Influence of the sanitary state of acorns on the regeneration of Quercus suber in Tunisia. In Tunisia, Cork oak forests represent ecosystems of fundamental ecological importance for the preservation of genetic resources and for environmental protection at both national and global scale. They present numerous assets in touch with their great biological diversity and their impact on the environmental and socioeconomic balance. The object of the present study was the characterization of the natural regeneration of Cork oak and of the action of insects on acorns. It allowed us to spot certain parameters linked to the biology and to the ecology of the Cork oak generally and to the acorns in particular, in North-western Tunisia. We determined the various biometric parameters of acorns according to whether they were healthy or affected by insects, such as length, diameter and weight of acorns coming from different strata of harvests and different exposures. We showed that acorns affected by insects have their length, diameter and weight lower than the non-affected healthy ones. The importance of the attacks of acorns by insects explains partially the deficiency of the natural regeneration of the Cork oak observed in our forests. This situation causes modifications at the level of the structure, diversity and density of seedlings. Our results allow recommendations for the natural regeneration of cork oak : (i) for the seedling by acorn use non-attacked acorns and avoid collecting acorns which had fallen on the ground ; (ii) use also the technique of rejections of origins.

Benthic foraminiferal paleoenvironmental reconstruction from the Upper Coniacian-Lower Campanian succession in north-western Tunisia

Quantitative analysis of benthic foraminifera is used to characterize the paleoenvironments of the Upper Coniacian-Lower Campanian succession in the Jbil section of north-western Tunisia. Foraminiferal parameters and benthic foraminiferal assemblages show that the studied section includes four distinct paleoenvironmental phases. From oldest to youngest, these are as follows: (1) an interval with a Praebulimina reussi assemblage with infaunal ratios as high as 96.1%. High abundances of P. reussi, reflecting an increase in organic matter flux to the seafloor (meso-to eutrophic) under oxygenated bottom-water conditions. (2) An interval characterized by a Gavelinella costulata assemblage with mixed infaunal/epifaunal foraminifera with higher Fisher's alpha values (ranging from 4 to 15.2), reflecting mesotrophic conditions in an outer shelf environment. (3) An interval with a Gaudryina laevigata assemblage indicative of a middle to outer shelf environment; there is a considerable increase in infaunal agglutinated foraminifera, as well as a relatively abundant and moderately diversified oxic/suboxic foraminifera. (4) The final interval occurs in the lower Campanian (the Globotruncana ventricosa Zone) and includes a Bolivinoides decoratus assemblage reflecting an outer shelf to upper bathyal environment. It contains a higher planktonic percentage and biodiversity with a slight increase in dysoxic species; the mixed infaunal/epifaunal content (57.6 to 73.3%) reflects mesotrophic conditions. Four well-recognized major sea-level falls are matched by the dual signatures of eustatic sea-level changes. These are coincident with the results of this study, which represent the first documentation of these events in Tunisian faunal and paleoenvironmental changes, at the following boundaries: Coniacian/Santonian, intra-Santonian, Santonian/Campanian, and intra-early Campanian.

Geotechnical Study of the Aptian Limestone of the Kef Region, Northwestern Tunisia: Evaluation for Industrial Use

This study aims to the initial characterization of Aptian sedimentary limestones in the Kef region located in the North-West of Tunisia in order to use in industrial fields. The limestone samples were collected from three outcrops respectively named Jebel Jerissa, Jebel Hmeima and Jebel Harraba. A geochemical characterization highlights a variation of the weight percentage (wt%) as follows: CaO (53 - 55), MgO (0.04 - 0.28), Al2O3 (0.07 - 0.51), Fe2O3 (0.41 - 2.87), and a loss on ignition (41.62 - 43.35). The other oxides (K2O, SO3, Na2O) are in trace amounts. Mineralogical analysis revealed that limestones contain more than 95% of calcite and the clay impurities are the minor phases detected. Petrographic study showed that these limestones are packestone-wakestone type. The hardness of Aptian limestones crosses the upper limit of the hard domain. Geotechnical tests reveal a Dry Micro Deval (MDS) coefficient varying from 23% to 33%, a Wet Micro Deval (MDH) coefficient with values oscillating around 26% to 36%, a Los Angeles coefficient (LA) about 25% against a value of the compressive strength ranging from 593 Kg/cm2 to 866 Kg/cm2. The gravimetric tests highlighted a flexural strength value from 106 Kg/cm2 at 208 Kg/cm2, while the ultrasonic coefficient oscillates from 4876 m/s to 5233 m/s, indicating the low porosity of these limestone (0.5% to 1%). The density recorded an average value of 2.50 g/cm3. The various properties studied have proved that the limestone studied can be used in various industrial fields such steel industry, aggregate, cement industry and marble.

Tethyan plankton bioevents calibrated to stable isotopes across the upper Santonian–lower Campanian transition in north-western Tunisia

Calcareous nannofossil and planktonic foraminifera biostratigraphic datums are correlated with carbon isotope stratigraphy across the upper Santonian–lower Campanian transition from Ain Zouakra outcrop (Ellès area) in north-western Tunisia. Twenty two calcareous microplankton bio-events are identified and discussed, including 11 planktonic foraminiferal and 11 nannofossil events. The studied upper Santonian–lower Campanian succession can be divided into five nannofossil zones (CC17/UC13 to CC21/UC15c) equivalent to three planktonic foraminiferal zones named Dicarinella asymetrica, Globotruncanita elevata, Globotruncana ventricosa. The Santonian/Campanian Boundary Event (SCBE) is characterized by a positive δ13C double peaks. The first peak (a) occurs within the uppermost CC17 Zone and Dicarinella asymetrica Zone. The second peak (b) directly occurs below the base of CC18 (FO of Bronsonia parca parca) and last occurrence (LO) of Dicarinella asymetrica. It is marked by several extinction bioevents of representatives of Whiteinella, Dicarinella and Sigalia and the gradual disappearance of species of Marginotruncana (all species except M. sinuosa and M. marginata). At the beginning of the Campanian a diversification of Globotruncanidae was noted.

Hydrochemistry and stable isotopes (δ18O and δ2H) tools applied to the study of karst aquifers in southern mediterranean basin (Teboursouk area, NW Tunisia)

Karst aquifers receive increasing attention in Mediterranean countries as they provide large supplies water used for drinkable and irrigation purposes as well as for electricity production. In Teboursouk basin, Northwestern Tunisia, characterized by a typical karst landscape, the water hosted in the carbonates aquifers provides large parts of water supply for drinkable water and agriculture purposes. Groundwater circulation in karst aquifers is characterized by short residence time and low water-rock interaction caused by high karstification processes in the study area. Ion exchange process, rock dissolution and rainfall infiltration are the principal factors of water mineralization and spatial distribution of groundwater chemistry. The present work attempted to study karstic groundwater in Teboursouk region using hydrochemistry and stable isotopes (δ18O and δ2H) tools. Karst aquifers have good water quality with low salinity levels expressed by TDS values largely below 1.5 g/l with Ca-SO4-Cl water type prevailing in the study area. The aquifers have been recharged by rainfall originating from a mixture of Atlantic and Mediterranean vapor masses.

Physico-chemical and geotechnical characterization of Bargou clays (Northwestern Tunisia): application on traditional ceramics

The Lower Aptian clays of the Drija formation (Jebel Bargou-Siliana, Tunisia) have been studied for their use in the ceramic industry. The physico-chemical characterization and advanced technological tests were carried out on two samples, Bargou 1 and Bargou 2 using many analytical methods. The samples indicate that these clays can be considered as a non-refractory material. The X-ray diffraction mineralogical analysis on whole rock and clay fractions reveals the presence of phyllitic minerals (illite, kaolinite, and interstratified illite/smectite). Associated minerals are mainly represented by dolomite, calcite, quartz and feldspar, and occasionally gypsum. The chemical analysis of major elements reveals a moderate level in Al2O3 (10–18%) and SiO2 (36–64%) with a SiO2:Al2O3 ratio that can reach level 3 and a low CaO content. The plasticity index of the samples, cut from the Drija formation, shows that they are low plastic clays (l2% < IP < 15%). The drying curves of various samples show that the clay materials have a quick drying behavior since they have a relatively low drying shrinkage. The tested briquettes, fired at different temperatures of 950, 1050, and 1100 °C, remain flat without deformations or defects; they are of red brick color. These briquettes show a high mechanical resistance to flexion and a good sound. The results obtained show that the Drija formation clays of Lower Aptian from the Bargou region can be directly used in the manufacture of tiles.

Copper-induced changes in nutrient uptake, enzymatic and non-enzymatic antioxidant systems in horehound ( Marrubium vulgare L.)

Background: The effect of different concentrations (80, 200 and 300 mg/L) of copper (Cu2+) on physiological parameters of horehound ( Marrubium vulgare L.) was studied. Once Horehound was cultivated in pots, element uptake and antioxidant system efficiency have been evaluated.Questions: What is the effect of copper on the physiological parameters of Marrubium vulgare ? What are the defense strategies developed by this plant to overcome cupric stress?Species study: horehound ( M. vulgare ) medicinal plant from the family of Lamiaceae.Study site and dates: Seeds of M. vulgare were issued from a non contaminated wild population in the region of Béja (Northwestern Tunisia). Culture of M. vulgare was conducted in 1 August 2014 and lasted 4 months.Methods: The Cu, Fe, K, Mg and Ca contents have been determined. Total phenolic and flavonoid contents have been determined. The free radical scavenging activity (DPPH test) together with SOD, CAT and APX antioxidant enzymatic activity have been evaluated.Results: In the aerial part extracts, Copper stress reduced the uptake and translocation of the cationic elements Fe2+, K+ and Ca2+, in a Cu2+ concentration-dependent manner. The treatment with copper gives rise to positive effects on antioxidant enzymes activities (SOD and CAT enzymes) and to an increase of total phenol and flavonoid contents. Unexpectedly, no correlation with the anti-radical scavenging activity was observed.Conclusions: M. vulgare possess an intrinsic capability to cope with the Cu stress by activation of the enzymatic and non-enzymatic antioxidant systems.

A contribution of gravity and seismic data in understanding the geometry of the Zouaraa - Ouchtata dune (NW Tunisia): Hydrogeological implications

As it is located in a very particular and complex domain within the Tellian fold and thrust belt zone in northwestern Tunisia, the Nefza area has always been challenging. Geological, hydrogeological and geophysical studies were conducted in the region. A multidisciplinary study was performed by combining geological and geophysical techniques.Gravity data processing revealed the continuity of the outcropping series of Argoub Er Romane and Jebel Hamra underneath the dune deposits building a high zone separating the dune of Zouaraa and Ouchtata into two asymmetric basins. It forms a threshold zone that controls the geometry of the dune reservoir in the area. The distribution of the gravity anomaly along the dune of Zouaraa proved the heterogeneity of this dune reservoir. Gravity data modeling for this area confirmed these results and showed a preferential tendency of subsidence to the northwest and thus the thickening of Zouaraa dune sequence as compared to that of Ouchtata.

Assemblages of fungi associated with cork oak forests in northwestern Tunisia

The cork oak forests of Ain Draham in northwestern Tunisia are characterized by a rich biodiversity of fungi, including edible, non-edible and toxic species. Sporocarps of 117 species of macrofungi collected from the forests of Jbel el Bir at different elevations were found to represent 26 families of the Agaricomycotina. Selected taxa are described herein, along with information on edibility and ecological importance. Among these there were 33 species of ectomycorrhizal fungi, 10 species of saprotrophic fungi and one species that is parasitic. Molecular identification of fungi from cork oak root-tips revealed the presence of such ectomycorrhizal species as Amanita rubescens, Laccaria bicolor, Lactarius subumbonatus, Cortinarius incisus, and Xerocomus rubellus along with a taxon identified only to genus level as Clavulina sp. Other taxa recorded from the rhizosphere of cork oak included Mortierellales and other mitosporic fungi (e. g., Sarcopodium circinatum).

Modelling the spatial distribution of snake species in northwestern Tunisia using maximum entropy (Maxent) and Geographic Information System (GIS)

We used GIS and maximum entropy to predict the potential distribution of six snake species belong to three families in Kroumiria (Northwestern Tunisia): Natricidae (Natrix maura and Natrix astreptophora), Colubridae (Hemorrhois hippocrepis, Coronella girondica and Macroprotodon mauritanicus), and Lamprophiidae (Malpolon insignitus). The suitable habitat for each species was modelled using the maximum entropy algorithm, combining presence field data (collected during 16 years: 2000–2015) with a set of seven environmental variables (mean annual precipitation, elevation, slope gradient, aspect, distance to watercourses, land surface temperature and normalized Differential Vegetation Index. The relative importance of these environmental variables was evaluated by jackknife tests and the predictive power of our models was assessed using the area under the receiver operating characteristic. The main explicative variables of the species distribution were distance from streams and elevation, with contributions ranging from 60 to 77 and from 10 to 25%, respectively. Our study provided the first habitat suitability models for snakes in Kroumiria and this information can be used by conservation biologists and land managers concerned with preserving snakes in Kroumiria.

Geophysical Contributions to Hydrogeological Study in the Chemtou–Sidi Miskine Agricultural Sector (Northwestern Tunisia)

This study presents an example of the use of geophysics for agricultural water management. Borehole data, gravity measurements and vertical electrical soundings were used to reconstruct a precise hydrogeological scheme of the Chemtou–Sidi Meskine area (Northwest of Tunisia) in order to assist exploitation and judicious management of the underground water resources for irrigation. The Chemtou–Sidi Meskine area belongs to Mejerda basin, the most important agricultural sector in Tunisia. It is characterized by the coexistence of alluvial and basement aquifers, which are very scare in this country. The computed gravity maps emphasize an E–W lineament separating Hairech metamorphic formations and Mejerda alluvial deposits. The apparent resistivity maps confirm the presence of this lineament. The interpreted vertical electrical soundings are correlated with lithological columns to give more accurate structural patterns. The resulting geoelectrical cross sections highlight a normal fault network that collapsed metamorphic aquifers, controlled the Quaternary alluvial aquifers thickness and created closed areas with high water salinity that is unfavorable for exploitation.

Budburst phenology and host use by Operophtera brumata (Linnaeus, 1758) (Lepidoptera: Geometridae) in three Mediterranean oak species

Operophtera brumata L. performance varies among three Mediterranean oak species. Quercus canariensis Willd is more susceptible to infestation probably due to its (i) early leafing, (ii) high nutritional value for the larvae, and (iii) widespread abundance. Larvae of Operophtera brumata were observed for the first time in an outbreak in Tunisia affecting Quercus canariensis, Quercus afares Pomel, and Quercus suber L. Due to its polyphagous nature and the important ecological and economic damage it causes, it is most relevant to understand its interaction with North African oaks species. In this paper, budburst phenology of the three oak species, larval performance, and genetic patterns of O. brumata were studied in northwestern Tunisia. In the spring of 2010, 2011, and 2012, budburst phenology of host species and larval densities were monitored weekly. Larval performance of O. brumata on the three oak species was analyzed. DNA extraction, PCR, and DNA sequencing were performed. Budburst of Q. canariensis and Q. afares was earlier than Q. suber. Q. canariensis was the most infested host. Larvae which fed on Q. canariensis had faster development, lower mortality, and higher pupal weight than larvae fed on Q. afares and Q. suber. Molecular analyses showed that Tunisian haplotypes were not different from those in Spain, Italy, and Germany. Results indicated differences in larval performance. Q. canariensis was the most favorable host species. Its high density in the field and early leafing coinciding with larval hatching made this species particularly susceptible.