Coarse-resolution Ecology of Etiological Agent, Vector, and Reservoirs of Zoonotic Cutaneous Leishmaniasis in Libya

Cutaneous leishmaniasis ranks among the tropical diseases least known and most neglected in Libya. World Health Organization reports recognized associations of Phlebotomus papatasi, Psammomys obesus, and Meriones spp., with transmission of zoonotic cutaneous leishmaniasis (ZCL; caused by Leishmania major) across Libya. Here, we map risk of ZCL infection based on occurrence records of L. major, P. papatasi, and four potential animal reservoirs (Meriones libycus, Meriones shawi, Psammomys obesus, and Gerbillus gerbillus). Ecological niche models identified limited risk areas for ZCL across the northern coast of the country; most species associated with ZCL transmission were confined to this same region, but some had ranges extending to central Libya. All ENM predictions were significant based on partial ROC tests. As a further evaluation of L. major ENM predictions, we compared predictions with 98 additional independent records provided by the Libyan National Centre for Disease Control (NCDC); all of these records fell inside the belt predicted as suitable for ZCL. We tested ecological niche similarity among vector, parasite, and reservoir species and could not reject any null hypotheses of niche similarity. Finally, we tested among possible combinations of vector and reservoir that could predict all recent human ZCL cases reported by NCDC; only three combinations could anticipate the distribution of human cases across the country

Control of sand flies with attractive toxic sugar baits (ATSB) and potential impact on non-target organisms in Morocco

International audienceBackground: The persistence and geographical expansion of leishmaniasis is a major public health problem that requires the development of effective integrated vector management strategies for sand fly control. Moreover, these strategies must be economically and environmentally sustainable approaches that can be modified based on the current knowledge of sand fly vector behavior. The efficacy of using attractive toxic sugar baits (ATSB) for sand fly control and the potential impacts of ATSB on non-target organisms in Morocco was investigated. Methods: Sand fly field experiments were conducted in an agricultural area along the flood plain of the Ourika River. Six study sites (600 m x 600 m); three with ``sugar rich'' (with cactus hedges bearing countless ripe fruits) environments and three with ``sugar poor'' (green vegetation only suitable for plant tissue feeding) environments were selected to evaluate ATSB, containing the toxin, dinotefuran. ATSB applications were made either with bait stations or sprayed on non-flowering vegetation. Control sites were established in both sugar rich and sugar poor environments. Field studies evaluating feeding on vegetation treated with attractive (non-toxic) sugar baits (ASB) by non-target arthropods were conducted at both sites with red stained ASB applied to non-flowering vegetation, flowering vegetation, or on bait stations. Results: At both the sites, a single application of ATSB either applied to vegetation or bait stations significantly reduced densities of both female and male sand flies (Phlebotomus papatasi and P. sergenti) for the five-week trial period. Sand fly populations were reduced by 82.8% and 76.9% at sugar poor sites having ATSB applied to vegetation or presented as a bait station, respectively and by 78.7% and 83.2%, respectively at sugar rich sites. The potential impact of ATSB on non-targets, if applied on green non-flowering vegetation and bait stations, was low for all non-target groups as only 1% and 0.7% were stained with non-toxic bait respectively when monitored after 24 hours. Conclusions: The results of this field study demonstrate ATSB effectively controls both female and male sand flies regardless of competing sugar sources. Furthermore, ATSB applied to foliar vegetation and on bait stations has low non-target impact

THE EFFECT OF PHOSPHORUS UTILIZATION EFFICIENCY ON DURUM WHEAT CULTIVARS UNDER SEMI-ARID ENVIRONMENTAL CONDITIONS

Faced with the high cost of phosphate fertilisers in several African countries, including Algeria, and in order to better select varieties according to their fertiliser use efficiency, this study was proposed. The goal of the study was to determine how “variety” impacts durum wheat's capacity to utilize phosphorus effectively and to try to pinpoint the agromorphological factors that contribute to this efficiency so that they can be taken into consideration when choosing which varieties to sow in semi-arid environments. The experimental setup consisted of a split plot with two investigated factors and three repetitions, with the main plot receiving the phosphate treatment while the sub plot receives the variety. The trial set up consisted of 11 durum wheat varieties, which were cultivated over two years successively. The PUE of the fertiliser, provided in 46% triple superphosphate (TSP) granules, and agro-morphological parameters like aerial biomass, plant height, grain yield and yield components were determined. The findings demonstrated that triple superphosphate, a type of phosphorus fertilizer, increases grain yield by between 40 and 60% for all varieties examined as compared to the phosphorusfree control at the average dose employed in this field trial, or 20 kg P2O5.ha-1. This increase in yield is due to an increase: from 20 to 22% in the number of ears per m², 41.5% in the number of grains per ear, and 9% in the average weight of the grain. The PUE is strongly correlated to the yield components (Number of ears per square meter- NEM, Number of grains per ear- NGE, thousand grain weight- TGW and Yield) but also to the height at heading (r=0.86) and dry matter (r=0.85). Phosphorus use efficiency is also strongly correlated to flag leaf length and width as well as leaf area. Also, that genotypes with higher weight of thousand grains (WTG) showed better use of available phosphorus. The principal component analysis (PCA) confirms that the efficiency of phosphorus use by the varieties tested explains a large portion of the variation noted in these varieties. This genetic variation in PUE was associated with plant height and phosphorus content of the sown grains. These results could be of a significant impact in improving rainfed durum wheat productivity in semi-arid areas and preserving the environment as well

Sand Dune Characterization for Preparing Metallurgical Grade Silicon

Dune sand, from Biskra, Algeria which is in the Great Algerian huge desert attracts tourists from all over the world. Dune sand composes around 80% of the total area of the desert. To date only a few studies have been conducted on this sand. The purpose of the present study is to shed light on the textural and physico-chemical characteristics of this sand using several characterization methods, and to understand the potential for using for photovoltaic applications. The chemical composition of Biskra sand indicated a high purity quartz with 97.6% silica, and a presence of others oxides. Granular analysis enabled the determination of the size of the sand grains which was found to be fine to medium. On the other hand, a Scanning Electron Microscopy and optical observations were carried out, the micrographs observations indicated the presence of different shapes of sand grain, some rounded whereas others are angular edged or elongated. X-ray diffraction indicates the highly crystalline nature of the Biskra sand

Nocturnal activity of phlebotomine sandflies (Diptera : Psychodidae) in a cutaneous leishmaniasis focus in Chichaoua, Morocco

The nocturnal activity of phlebotomine sandflies (Diptera: Psychodidae) was studied "at an epidemic focus" on human cutaneous leishmaniasis due to Leishmania tropica Wright in Chichaoua province, in Morocco. Sandflies were collected using light and sticky-paper traps changed at 2-h intervals, inside and around houses, in August and October 2004. Overall, 633 sandflies, belonging to six species of Phlebotomus and three of Sergentomyia, were collected. Sandfly activity was nocturnal and higher at twilight. Several activity patterns were observed according to the species. Phlebotomus (Paraphlebotomus) sergenti Parrot, 1917, the suspected vector of L. tropica in this focus, was caught during each collection performed from 1900 to 0500 hours, the numbers of species caught peaked at 1900 2100 hours. There were seasonal variations of the nocturnal activity, which could be related to the variations in temperature and relative humidity