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Group living has various benefits, but it also carries costs, such as risk of cannibalism. Molting is a vulnerable period of being cannibalized in juvenile arthropods, but how gregarious arthropods avoid this threat is poorly understood. Here, we examined how actively migrating gregarious nymphs of desert locust, Schistocerca gregaria , avoid cannibalism during molting, in the Sahara Desert of Mauritania. In the field, gregarious nymphs cyclically march and feed on grass during the day. Our field observations found that marching behavior helped separating pre-molting and cannibalistic non-molting nymphs. Cannibalistic non-molting nymphs marched away from roost plants, leaving sedentary pre-molting nymphs behind, creating cannibal-free spaces. Some non-molting nymphs reached a pre-molting state after daytime marching, thus both pre- and non-molting nymphs roosted on same plants at night. However, pre-molting nymphs moved away from conspecifics prior to molting. Starvation experiments confirmed that food-satiation decreased cannibalistic necrophagy. Physiological surveys of diel feeding and molting patterns revealed that nymphs molted at times when conspecifics were food-satiated rather than hungry. Hence, our results indicate that behavioral and physiological traits of gregarious locusts could function to spatiotemporally separate molting locusts from cannibalistic conspecifics, thus reducing molting-associated cannibalism. This is the first report of migration-dependent molting synchrony as a mechanism reducing costs of aggregation in gregarious arthropods. [ABSTRACT FROM AUTHOR]

Seven date seeds cultivars, Deglet Nour, Degla Baïdha, Fakht, Ghars, Hamraya, Tafezouin and Takermost were provided from Algerian Sahara. Some of these Algerian date seeds were studied for the first time (Fakht, Hamraya and Takermost). The biochemical characterization of these date seeds were studied, including fatty acids and minerals profiles. The results showed that date seeds are a good source of carbohydrates and crude cellulose, with averages of 66.63 and 13.20%, respectively. They are also a good source of proteins, with the cultivar Deglet Nour seeds as the richest one (9.27 ± 0.03%). The main fatty acid for all date seeds oils is oleic acid except for Deglet Nour in which lauric acid is the main one. However, the studied date seed oils could be classified as oleic-lauric oil. Potassium was the highest mineral in all date seeds cultivars, with values ranging from 2700 to 2900 mg/Kg, followed by sodium and iron. These results indicate that date seeds have good nutritional value with different compositions among cultivars. It could be concluded that date seeds could be considered as a good opportunity for their technological and industrial valorization. [ABSTRACT FROM AUTHOR]

The survival and growth of Adansonia digitata tall bare-roots were tested in farm fields at Bankass (Mali). Saplings were planted by involving l4 farmers. The survival rate, the diameter at the basis, the diameter at breast height and the total height were recorded at three and fifteen months after planting. The mean survival rate after three months was 98%, and it decreased to 82% after 15 months. The mean survival rate of A. digitata tall bare-roots was higher than of those planted by using container seedlings (52–59%) and short bare-roots (< 5%). The means of growth variables were 5.44 cm, 2.30 cm and 228 cm for DB, DBH and TH, respectively. The annual increments were 0.4 cm year−1 for DB, 0.47 cm year−1 for DBH and 34 cm year−1 for TH. The mean annual height increment of tall bare-roots (34 cm year−1) was higher than that of container seedlings (17–22 cm year−1). Based on these findings, tall bare-roots of A. digitata could be successfully used for enriching parklands at Bankass and restore the vegetation. They have a better chance to resist and survive harsh climatic conditions, and farmers highly value the use of this plant material in their fields. More widely, tall bare-roots of A. digitata could be used in larger-scale restoration projects in similar contexts and conditions in the Sahara and Sahel region. [ABSTRACT FROM AUTHOR]

Assisted natural regeneration approach was experimented in the Sahel region in the aim of restoring land and vegetation in accordance with the global objectives of the Great Green Wall for the Sahara and the Sahel Initiative. Two sites (Endé and Soula Kanda) located in the district of Bankass in the centre of Mali were concerned by this study. Assisted shoots and non-assisted shoots of Guiera senegalensis J. F. Gmel. were compared at Soula Kanda, while at Endé, only assisted shoots were monitored so that to assess the impact of this approach on the survival and the growth of the shoots of this species. The height, the diameter at the basis and the diameter at 1.30 m above the ground were measured from 2015 to 2017 at Endé and from 2016 to 2017 at Soula Kanda in November/December each year. For each treatment, thirty shoots were monitored and data were analysed using the software SYSTAT9 FOR WINDOWS. At Endé, the survival rate was 93%. At Soula Kanda, the survival rate of assisted shoots was 97% against 73% for the control. At Endé as well as at Soula Kanda, dead shoots were cut by farmers. The current annual increments at Endé were 44 cm year−1 for height and 1.27 cm year−1 for the diameter at 1.30 m above the ground. At Soula Kanda, the current annual increment for height was the same for the two treatments (20 cm year−1). [ABSTRACT FROM AUTHOR]

All terrestrial ectotherms are constrained to some degree by their thermal environment and the extent to which they can behaviorally buffer variable thermal conditions. New biophysical modeling methods (NicheMapR) allow the calculation of the body temperature of thermoregulating animals anywhere in the world from first principles, but require detailed observational data for parameterization and testing. Here we describe the thermoregulatory biology of marching bands of the desert locust, Schistocerca gregaria, in the Sahara Desert of Mauritania where extreme heat and strong diurnal fluctuations are a major constraint on activity and physiological processes. Using a thermal infrared camera in the field, we showed that gregarious nymphs altered the microhabitats they used, as well as postural thermoregulatory behaviors, to maintain relatively high body temperature (nearly 40°C). Field and laboratory experiments demonstrated that the preferred body temperature accelerated digestive rates. Migratory bands frequently left foraging sites with full guts before consuming all vegetation and moved to another habitat before emptying their foregut. Thus, the repertoire for behavioral thermoregulation in the desert locust strongly facilitates foraging and digestion rates, which may accelerate developmental rates and increase survival. We used our data to successfully parameterize a general biophysical model of thermoregulatory behavior that could capture hourly body temperature and activity at our remote site using globally available environmental forcing data. This modeling approach provides a stronger basis for forecasting thermal constraints on locust outbreaks under current and future climates. [ABSTRACT FROM AUTHOR]

Most terrestrial animals are constrained by extreme heat conditions such as midday desert environments, while a few terrestrial ectothermic insects are active in such ecological niches. Sexually mature males of the desert locust (Schistocerca gregaria) in the Sahara Desert remain on the open ground, despite the ground temperatures exceeding their lethal limit, to form leks and to mate incoming gravid females during the daytime. Lekking male locusts apparently suffer from extreme heat stress and greatly fluctuating thermal conditions. The present study examined the thermoregulatory strategies of the lekking male S. gregaria. Our field observations showed that lekking males changed their body orientation toward the sun depending on the temperature and time of day. In the relatively cool morning, males basked by orienting perpendicular to the sun's rays, maximizing the area of body surface exposed to the sun's rays. In contrast, around midday, when the ground surface temperature exceeded lethal high temperatures, some males tended to shelter inside the plants or remain in the shade. However, the remainder stayed on the ground, stilted (i.e., extending their legs to raise their bodies off the hot ground) and oriented parallel to the sun's rays, which minimized radiative heating. Measurements of body temperature throughout the hot middle period of the day confirmed that the stilting posture prevented overheating. Their critical lethal body temperature was as high as 54.7 °C. In this lekking system, gravid females enter male leks by flying. These incoming females usually landed on open ground, whereupon nearby males immediately approached, mounted, and mated the female, implying that males with greater heat-tolerance can increase mating chance. These results suggest that behavioral thermoregulation and physiologically high heat tolerance of male desert locusts allows them to endure extreme thermal conditions for lekking. [Display omitted] • Thermoregulatory strategies of the lekking desert locust male were investigated. • Lekking males exhibited behavioral and physiological strategies to tolerate heat. • Stilting posture prevented overheating. • Desert locust males have one of the highest known thermal tolerances of the species of insects. [ABSTRACT FROM AUTHOR]

It is now irrefutable that air pollution caused by large amounts of Total Suspended Particulates (TSP) and respiratory particulates or Particulate Matter less than 10 μm in aerodynamic diameter (PM10) has numerous undesired consequences on human health. Air quality degradation far from the African continent, in the US and in Europe, caused by high concentrations of African dust, is seen as a major threat even though most of these countries are very distant from the Sahara. Surprisingly, no estimates of TSP or PM10 levels near the Saharan dust source are available. Based on horizontal visibility observations which are reduced by the presence of dust in the atmosphere, TSP and PM10 levels are estimated throughout the year 2000 at Nouakchott-Airport, Mauritania, using relations found in the literature. It appears that concentrations of particles are significant both in terms magnitude and frequency, as the 24-hour PM10 thresholds established by the US EPA National Ambient Air Quality Standards and the EU Limits Values for Air Quality were exceeded 86 and 137 times, respectively. The average annual concentration is far above air quality standards and estimated at 159 μg m−3 for TSP and 108 μg m−3 for PM10. These very high particulate levels are likely to represent an important public health hazard and should be considered as a major environmental risk. [ABSTRACT FROM AUTHOR]

The desert locust, Schistocerca gregaria, is a major migratory pest that causes substantial agricultural damage. Flying adult swarms disperse widely during the daytime, but they densely roost on plants at night. Swarm control operations are generally conducted during the daytime, but night-time control is a significant potential alternative. However, the night-roosting behavior of swarms is poorly understood. We determined night-roosting plant preferences of migrating sexually immature swarms of S. gregaria at four different sites in the Sahara Desert in Mauritania during winter. The night-roosting sites were divided into two types based on presence or absence of large trees. Swarms tended to roost on the largest trees and bushes at a given site. Swarms used medium-sized plants when large trees were not locally available, but the same medium-sized plant species were hardly used when large trees were available. Plant choice influenced roosting group size—large locust groups roosted on larger plants. Night-roosting locusts rarely fled from approaching observers. These results suggest that swarms of S. gregaria exhibit plasticity in their utilization patterns of night-roosting plants depending on the plant community encountered and they selectively use larger plants. We propose that this predictable plant-size dependent night-roosting can be used to particularly ease locust swarm control and to generally adopt anti-locust night control strategy. [ABSTRACT FROM AUTHOR]

This study presents an assessment of the wind potential over the whole Algerian territory, based for the first time on a reanalysis dataset. Thereby, 33 years (1981–2014) of 6-hourly wind components from ERA-Interim reanalysis are used for assessing the wind energy large-scale features over the largest country in Africa. The ERA-Interim data are validated against observational wind speeds from 42 sites across Algeria by using the two-sample Kolmogorov-Smirnov and the Wilcoxon–Mann–Whitney tests, while the Generalized Extreme Value (GEV) theretical distribution is used to characterize wind speeds. Overall, the ERA-Interim dataset validation reveals good agreement with observations in the south and less near the coastline. The mean wind speed and prevailing wind direction are assessed on the annual, monthly and hourly timescales. Mean wind speeds ranging between 2.3 m s−1 in the North, and 5.3 m s−1 in the South are found. Furthermore, the windiest periods are the warmer months and during daytime over almost all of the country. The gridded wind energy outputs for a representative wind turbine (850 kW) are also assessed. These informations are of foremost relevance to decision-makers and to the energy production sector in Algeria, providing guidelines for new wind farms installations. • ERA-Interim reanalysis used to assess wind resources over Algeria. • Validation with 42 in situ measurement points for the year 2014. • Temporal wind resource assessment with prevailing wind direction over Algeria. • Wind energy output evaluation based on a 850 kW wind turbine. • Most of Sahara and coastline reveal high wind energy production potential. [ABSTRACT FROM AUTHOR]

Abstract To disseminate rice husk in rice-growing environments in Africa through the production of renewable thermal energy with less smoke for cooking, a water boiling test protocol was used to compare four fan-assisted rice husk gasifier cookstoves [Rua (RRHS), Viet (VRHS), Paul Olivier 150 (PO150) and Paul Olivier 250 (PO250)] in comparison with a natural draft gasifier [(Mayon (MYN)]. Workplace emissions were compared for different cookstoves and burner types (pore and vent). Furthermore, the effect of mixing different proportions of rice husk and palm kernel shell on burning time and flame temperature was investigated. The feasibility of disseminating these cookstoves was evaluated by end-users using the controlled cooking test protocol. Fan-assisted cookstoves with vent-type burners were safer to use as they produced both lower concentrations of flue gases and particulate matter. The fan-assisted cookstoves also recorded better thermal indices. Rice husk mixed with palm kernel shell at varying proportions burned for a longer time than rice husk only, but this mixing had no effect on flame temperature. End-users preferred fan-assisted (RRHS, VRHS, PO150/PO250) gasifiers to the Mayon natural draft gasifier cookstove. Gasifier cookstove acceptability was positively correlated with five stove descriptors making them important in future fine-tuning and design. Graphical abstract Image 1 Highlights • Newly introduced rice husk stoves had better performance metrics than that existing in the region. • Rice husk mixed with palm kernel shell increase burning time but not flame temperature. • Data from end-user evaluation were in conformity with stove performance metrics determined instrumentally. • Five factors were identified that positively correlated with stove acceptability. [ABSTRACT FROM AUTHOR]

• Living diatoms from an oasis in the deep Sahara were obtained. • They were kept into culture and identified using multipronged microscopy/next generation sequencing approach. • They belong to cosmopolitan taxa commonly found in degraded waters in Europe. • Genomics provided new insights on diatoms organellar genomes. • Genomic data could be used for further phylogeography of Saharan diatoms. A water sample was obtained from an arheic oasis in the deep Sahara Desert, the Gueltates Afilal in Tamanrasset (Algeria). Five diatom strains were isolated, cultivated and identified as Tryblionella apiculata , Nitzschia supralitorea , Fistulifera saprophila , Navicula veneta and Thalassiosira pseudonana using a combination of scanning electron microscopy and next generation sequencing. The diatoms identified are opportunistic and cosmopolitan species with known tolerances to organic pollution and variations in salinities, often found in meso- and polysaprobic zones in Europe. Their complete organellar genomes have been sequenced and some exhibit features never observed among diatoms before. To our knowledge this is the first time that living specimens of diatoms from the deep Sahara are identified using modern taxonomical tools in the frame of a study which also demonstrates the possibility to cultivate such material in laboratories for further experiments on biogeography and bioindication. Our study also suggests that European identification keys can be effective when employed on diatoms from the Sahara. [ABSTRACT FROM AUTHOR]