Background Leishmaniasis is a vector-borne disease, caused by the infection of Leishmania parasites which are transmitted by the bite of infected female phlebotomine sand flies. Leishmania tropica is transmitted by Phlebotomus sergenti and Phlebotomus arabicus while the main reservoir host is the rock hyrax. A marked increase in the incidence of cutaneous leishmaniasis (CL) caused by L. tropica has been detected in recent years in Israel; it is associated with infections which have emerged in new urban and rural foci. The objective of this study is to contribute to a better understanding of the preferred habitat, spatial activities and host-sand fly relationships of both species of vectors within various types of land use. Methods Using CDC-type traps, we investigated the activity levels of sand flies. A field survey was conducted in 2016 at Elifelet, an agricultural village characterized by various types of land use. Movement patterns of P. sergenti between rock-piles were investigated by using colour-marked sugar baits and analyses of recapture patterns. In 2017, a survey was conducted in the hilly Jordan River area, by comparing sand flies and rock hyrax activities in relation to the size of rock-piles and vegetation cover. Results Both sexes of both species were found to have a clear preference for rocky habitats over other land use types in rural landscapes. Movement patterns of P. sergenti were characterized by their high presence close to the rocks and an exponential decrease in their recapture, commensurate with the distance from the rocks. Host-sand fly relationships were found to have a higher correlation between rock hyrax activity levels for females than for males of both species of sand flies. Males exhibited the strongest association with the size of rock-piles. Conclusions The results suggest a strong affinity of both phlebotomine vector species to the rocky habitats of the Mediterranean areas. We suggest that rock-piles are associated with populations of rock hyraxes attracting female sand flies seeking blood sources. Rapid human population growth, coupled with intensive land-use changes and the creation of artificial rock-piles, which created potential habitats for both vectors and hosts in the proximity of many settlements, have increased the prevalence of L. tropica among the human population in the region. Electronic supplementary material The online version of this article (10.1186/s13071-019-3562-0) contains supplementary material, which is available to authorized users.
Cutaneous leishmaniasis caused by Leishmania tropica, transmitted by Phlebotomus sergenti and Phlebotomus arabicus, has been detected in Israel. This research strives to identify the complexity of temperature effects on vectors of L. tropica and to analyze seasonality and distribution across altitudinal levels. Sand fly trappings were conducted monthly during 2015‐2016 in an endemic region for L. tropica in the eastern Galilee. Trappings were conducted in hyrax den sites across a broad topographic and climatic gradient. Using N‐mixture models, we investigated the activity levels of sand flies as related to temporary and periodic climatic variables. We tested generality of climate‐driven models using Root‐Mean‐Square Error (RMSE) values by comparing the 2015‐2016 data with trapping data from 2013. P. sergenti activity was found to be positively and exponentially correlated with early night temperatures and more strongly correlated with average early‐night temperatures for two weeks. P. arabicus exhibited a linear correlation with temperature. Climate‐driven models for both species yielded lower RMSE values for the 2013 data, which validate the generality of the models. Considerable differences were found in slope coefficients of temperature effect on sand fly activity among sites related to elevation levels, implying differential local responses of sand flies to temperature.
Graphical abstractHypothetical illustration of Anthroponotic Transmission Cycle of L. donovani in VL Endemic Villages in Northern Ethiopia. Transmission of L. donovani occurs anthroponotically in or close to households near to vertisols. Sand flies breeding in vertisols, are attracted into villages to feed blood on domestic animals, plant communities my serve as resting places for sand fly vectors.
BackgroundA previous multi-locus lineage (MLL) analysis of SSR-microsatellite data of old olive trees in the southeast Mediterranean area had shown the predominance of the Souri cultivar (MLL1) among grafted trees. The MLL analysis had also identified an MLL (MLL7) that was more common among rootstocks than other MLLs. We here present a comparison of the MLL combinations MLL1 (scion)/MLL7 (rootstock) and MLL1/MLL1 in order to investigate the possible influence of rootstock on scion phenotype.ResultsA linear regression analysis demonstrated that the abundance of MLL1/MLL7 trees decreases and of MLL1/MLL1 trees increases along a gradient of increasing aridity. Hypothesizing that grafting on MLL7 provides an advantage under certain conditions, Akaike information criterion (AIC) model selection procedure was used to assess the influence of different environmental conditions on phenotypic characteristics of the fruits and oil of the two MLL combinations. The most parsimonious models indicated differential influences of environmental conditions on parameters of olive oil quality in trees belonging to the MLL1/MLL7 and MLL1/MLL1 combinations, but a similar influence on fruit characteristics and oil content. These results suggest that in certain environments grafting of the local Souri cultivar on MLL7 rootstocks and the MLL1/MLL1 combination result in improved oil quality. The decreasing number of MLL1/MLL7 trees along an aridity gradient suggests that use of this genotype combination in arid sites was not favoured because of sensitivity of MLL7 to drought.ConclusionsOur results thus suggest that MLL1/MLL7 and MLL1/MLL1 combinations were selected by growers in traditional rain-fed cultivation under Mediterranean climate conditions in the southeast Mediterranean area.Electronic supplementary materialThe online version of this article (doi:10.1186/s12898-017-0114-3) contains supplementary material, which is available to authorized users.
Background: The wild radishes, Raphanus raphanistrum and R. pugioniformis (Brassicaceae) are native to the East Mediterranean region. However, whereas R. raphanistrum is widely distributed worldwide, the endemic R. pugioniformis is limited to specific habitats. In R. raphanistrum the diaspores of the indehiscent fruits comprise glabrous, light, single-seeded segments, whereas the intact fruits of R. pugioniformis are heavy and covered with spiny backwardpointing trichomes. We aimed to investigate whether the structure of the diaspores was directly associated with longand short-range dispersal in R. raphanistrum and R. pugioniformis, respectively. We further surveyed within-population spatial distributions, to test the hypothesis that short-and long-range dispersal contribute to a patchy vs. uniform distribution patterns of R. pugioniformis and R. raphanistrum, respectively. Results: The results indicated that dispersal by wind and runoff water was substantially lower for diaspores of R. pugioniformis than for those of R. raphanistrum diaspores. Supporting the hypothesis that backward-pointing trichomes promote adherence to soil particles, the displacement on soil surface of R. pugioniformis fruits depended on their orientation relative to wind direction. Furthermore, trichome removal from fruits of R. pugioniformis significantly reduced wind velocity needed to remove fruits that were placed on soils typical of the species' natural habitats. The spatial-distribution survey results indicated a patchy distribution of R. pugioniformis populations as compared with the more uniform arrangement in the studied populations of R. raphanistrum; consistent with the unidirectional vs. homogeneous wind dispersal of the respective diaspores, with respect to wind direction. In addition, R. pugioniformis population sizes changed less between years than those of R. raphanistrum. Conclusions: Overall, our results indicate that fruit structure is strongly linked to dispersal ability and spatial distribution of the two closely related wild radish species. Whereas R. raphanistrum inhabits homogenous sandy soil habitats, the distribution range of R. pugioniformis includes heterogeneous environments in which growth niches are scarcer. We suggest that the different modes of dispersal have evolved as adaptive traits appropriate to the species' specific habitats.
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