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211.
This study determined in vitro anthelmintic efficacy of three plant species: Trema orientalis, Urtica dioica and Zanthozylum capense on nematode larvae of small ruminants. Dried leaf samples (40 g) were extracted in 70% ethanol, in portions of 10 g and concentrated to 100 ml. Half and one quarter of the original crude extract were both made to 100 ml. Rectal faecal material from 10 Merino sheep and 25 Nguni goats was pooled within species and thoroughly hand-mixed. Dung samples, each of 5 g were cultured for 12 days at 27 °C. On day 13, 4 plates were watered and 4 others treated with ethanol to correct for solvent effect on mortality. The design was 2 (animal species)?×?3 (plant species)?×?3 (extract concentrations). In each of three runs, three plates were treated with each crude extract in three incremental concentrations. Surviving L3 larvae were isolated, counted and mortalities became indices of anthelmintic efficacy. Data from nematode larval mortality were analysed to determine the effect of animal species, plant species, concentration and their interactions. Efficacy was affected by concentration (P?=?0.0001), animal species (P?=?0.0046), plant species (P?=?0.0572), the interactions of animal species and concentration (P?=?0.0010), plant species and concentration (P?=?0.0123) and concentration × animal × plant species (P?=?0.0435). 相似文献
212.
Lissette C. Hernández-Cubero Peter Ampofo Juan M. Montes Ralf T. Voegele 《European journal of plant pathology / European Foundation for Plant Pathology》2017,147(2):325-337
Sexual reproduction in fungi is controlled by mating type genes, which are located at the MAT locus. In this study, we investigated the structure of this locus in the phytopathogenic fungus Phyllosticta citricarpa, the causal agent of citrus black spot disease. Despite intensive study, its sexual state has never been observed in single-spore culture. Through analysis of the genome sequences of two individual P. citricarpa isolates, the sequence of the DNA lyase gene was identified and, as previously reported in the literature, the mating type genes were located in the 3′ flanking region of this gene. The results suggested that P. citricarpa is heterothallic, owing to the exclusive presence of the MAT1–1 or MAT1–2 gene in individual strains. In order to characterize the MAT locus, we designed primers to amplify this region. P. citricarpa was found to have complete and apparently functional copies of MAT genes, containing α-1 and HMG domains, present in different isolates. In addition to MAT1–2-1 and MAT1–1-1 genes, the MAT1–1-4 gene was located in the 5′ flanking region of the MAT1–1-1 gene and the MAT1–2-5 gene was located in 5′ flanking region of the MAT1–2-1 gene. A multiplex PCR protocol was also developed to differentiate P. citricarpa idiomorphs, which can be used in distribution and incidence studies of mating type strains, in order to determine the occurrence of sexual reproduction and to facility crossing studies. Furthermore, in Brazil, the two idiomorphs occur in a 1:1 ratio, which is expected in sexually reproducing populations. 相似文献
213.
Philina A. English Joseph J. Nocera Bruce A. Pond David J. Green 《Landscape Ecology》2017,32(2):343-359
Context
Conservation research often focuses on individual threats at a single spatial scale, but population declines can result from multiple stressors occurring at different spatial scales. Analyses incorporating alternative hypotheses across spatial scales allow more robust evaluation of the ecological processes underlying population declines.Objectives
Populations of many aerially insectivorous birds are declining, yet conservation efforts remain focused on habitat due to an absence of data on changes in prey availability. We evaluate the potential for prey and habitat availability at multiple spatial scales to influence a population of eastern whip-poor-wills (Antrostomus vociferous).Methods
We assess relationships between landcover (topographical map and satellite imagery) and insect abundance (moths and beetles from blacklight traps), and whip-poor-will distribution and abundance within eastern Canada using Ontario breeding bird atlas data (1980s and 2000s), acoustic recordings (regional), and point counts (local).Results
Whip-poor-will occurrence in both atlas time periods was positively associated with forest area and fragmentation, but only a delayed effect of urban area explained reductions in detection. Contemporary regional whip-poor-will presence was positively related to moth abundance, and local whip-poor-will abundance was best predicted by area of open-canopy forest, anthropogenic linear disturbance density, and beetle abundance. Our finding that bird presence and abundance were associated with human activity and insect abundance across spatial scales suggests factors beyond habitat structure are likely driving population declines in whip-poor-wills and other aerial insectivores.Conclusions
This study demonstrates the importance of examining multiple hypotheses, including seasonally and locally variable food availability, across a range of spatial scales to direct conservation efforts.214.
A study to estimate the seroprevalence of Contagious Caprine Pluropneumonia (CCPP) in southern Ethiopia was conducted from November 2005 to June 2006. Two districts from sedentary (Arbaminch and Boreda)
and pastoral (Hammar and Bena-Tsemay) production systems were included in the study. Sera samples were collected from 913
goats (234 from sedentary and 679 from pastoral) to check for CCPP serostatus. The animals were sampled from 155 flocks (44
pastoral and 111 sedentary). Five clinically suspected CCPP cases were also sacrificed and attempt was made to isolate Mycoplasma capricolum capripneumoniae (MccP) from lung tissue, nasal swab and plural exudates. Sera samples were tested for the presence of CCPP antibodies using CFT.
The overall seroprevalence recorded in the study was 18.61%. The corresponding seroprevalences for sedentary and pastoral
production systems were 27.78% and 15.46% respectively. Regarding districts, the prevalence in Hammar was 15.63% while that
of Bena-Tsemay 15.29%. In Arbaminch and Boreda the percent of seroreactors were 23.01 and 32.23% respectively. Out of 44 pastoral
and 111 sedentary flocks, 50.45% of pastoral and 65.91% of sedentary flocks had at least one seroreactor goat per flock respectively.
Both in the univariable and multivariable logistic regression analysis, seropositivity was found to have strong association
with sedentary production system (P < 0.05, OR = 2.24) and adult age (P < 0.05, OR = 1.77). In microbiological study, two
broth cultures from thoracic fluid and two broth cultures from lung tissue samples were found to be positive for Mycoplasma capricolum capripneumoniae (MccP). In conclusion, both the serological study and bacteriological isolation confirmed the disease CCPP being an important disease
that demands serious attention in both production systems. 相似文献
215.
Carlos A. Guerra Marc J. Metzger Joachim Maes Teresa Pinto-Correia 《Landscape Ecology》2016,31(2):271-290
Context
Policy decisions form a major driver of land use change, with important implications for socially and environmentally susceptible regions. It is well known that there can be major unintended consequences, especially where policies are not tailored to regionally specific contexts.Objectives
In this paper we assess the implications of 60 years of agricultural policies on soil erosion prevention (SEP) by vegetation, an essential regulating ecosystem service in Mediterranean Europe.Methods
To assess these implications we produced and analysed a time series of land cover/use and environmental conditions datasets (from 1951 to 2012) in relation to changing agricultural policies for a specific region in the southern Portugal. A set of indicators related to SEP allowed us to identify that land use intensification as increased soil erosion in the last 60 years.Results
Particularly in the last 35 years, as a consequence of headage payments for cattle, the agricultural policy had a significant effect in the density and renewal of the tree cover, resulting in drastic effects for the provision of the SEP service. These are more significant after 1986, coinciding with the implementation of several Common Agricultural Policy instruments focused on increasing the modernization and productivity capacity of farm systems.Conclusions
The results show some unintended effects of agricultural policy mechanisms on ecosystem service provision and highlight the need for context-based policies, tailored to the environmental constrains and potentials of each region.216.
In Central Europe vast wetland areas have been converted into agricultural land over the past few centuries. Long-term spatially
explicit reconstructions of wetland cover changes at regional scale are rare but such information is vital for setting appropriate
wetland conservation and restoration goals. In this study wetland cover change over the past 150 years was analyzed for the
Canton Zurich (Switzerland) using information from historical and current topographical maps. Mapping instructions changed
significantly over time, i.e., wetlands were mapped more conservatively on older maps. Therefore a technique was developed
to account for changes in mapping instructions and to reconstruct a series of comparable maps spanning 1850–2000. Wetland
cover dramatically decreased from 13,759 ha in 1850 (more than 8% of the total study area) to 1,233 ha in 2000 (less than
1%). Largest loss is observed for the first half of the twentieth century when more than 50% of the total wetland loss occurred.
In 1850, almost all wetland patches were connected in two large networks defined by a 500 m buffer around all wetland patches
to account for typical dispersal distances of wetland animals. Despite extensive wetland loss, this networks remained largely
intact until 1950, but then collapsed into many medium and small networks consisting of only few wetland patches. In addition
to the direct loss of wetland habitats increased habitat fragmentation is limiting metapopulation dynamics and hindering genetic
exchange between populations. Amphibians and other wetland animals are particularly prone to habitat fragmentation because
of their limited migration abilities. This may lead to time-delayed extinction in the future because current species occurrence
might rather reflect historical than current wetland cover and habitat configuration. Future restoration efforts should focus
on reestablishing connectivity between remaining smaller wetland networks. 相似文献
217.
Quantifying landscape pattern and ecosystem service value changes in four rapidly urbanizing hill stations of Southeast Asia 总被引:1,自引:0,他引:1
Context
Hill stations are known for their favorable cool climate and natural environments which generate valuable ecosystem services that benefit the local population, tourists and visitors. However, rapid urbanization threatens the sustainability of these highly valued fragile landscapes.Objectives
We aim to characterize and quantify the changes in the landscape patterns and ecosystem service values (ESVs) of Baguio (Philippines), Bogor (Indonesia), Dalat (Vietnam), and Pyin Oo Lwin (Myanmar), and discuss their implications to landscape sustainability.Methods
We used remote sensing imagery to map land-use/cover (2001 and 2014), and spatial metrics and gradient analysis to characterize the changes in landscape pattern. We employed a benefit transfer method to estimate the changes in ESV and human-to-ESV ratio. A land-change model was used to simulate different scenarios of future built-up expansions (2014–2030).Results
The landscapes of Dalat and Pyin Oo Lwin are becoming more fragmented, while those of Baguio and Bogor are getting more aggregated. Dalat had the highest decrease (absolute change) in ESV and H-ESV ratio, while Bogor had the highest percentage decrease (2001–2014).Conclusions
Rapid urbanization has been a major factor in the landscape transformation of Baguio, Bogor, Dalat and Pyin Oo Lwin. If the current built-up expansion rate will speed up, the decline in future ESV and H-ESV ratio (2014–2030) will be higher than if the rate will continue or slow down. Unless the concept of landscape sustainability is taken seriously in landscape and urban planning, the respective ‘values’ of these precious hill stations will become less and less.218.
Although the role of habitat fragmentation in species declines is well recognised, the effect of habitat quality on species
distributions is often studied using presence–absence models that ignore metapopulation dynamics. We compared three approaches
to model the presence–absence of North Island robins in 400 sites among 74 fragments of native forest in a 15,000-ha agricultural
landscape in New Zealand. The first approach only considered local habitat characteristics, the second approach only considered
metapopulation factors (patch size and isolation), and the third approach combined these two types of factors. The distribution
of North Island robins was best predicted by patch isolation, as their probability of occurrence was negatively correlated
with isolation from neighbouring patches and from the closest major forests, which probably acted as a source of immigrants.
The inclusion of habitat factors gave only a slight increase in predictive power and indicated that robins were more likely
to occur in areas with tall canopy, tall understory and low density of young trees. We modelled the effect of isolation using
an index of functional patch connectivity based on dispersal behaviour of radio-tracked juveniles, and this functional index
greatly improved the models in comparison to classical indices relying on Euclidean distances. This study highlights the need
to incorporate functional indices of isolation in presence–absence models in fragmented landscapes, as species occurrence
can otherwise be a misleading predictor of habitat quality and lead to wrong interpretations and management recommendations. 相似文献
219.
Motoaki Tojo Ken Watanabe Kenichi Kida Yingjie Li Shuhei Numata 《Journal of General Plant Pathology》2007,73(2):121-124
Severe mottle necrosis (Shirogusare-byo in Japanese) was found on mature tubers of sweet potato (Ipomoea batatas) in Ibaraki Prefecture in October 2004. The causal organism was identified as Pythium scleroteichum hitherto unknown in Japan. Sweet potato cultivar Purple Sweet Lord was more susceptible than cultivars Beniazuma, Benimasari,
Koukei-14, and Tamayutaka to the pathogen at 25°C, while this difference in the susceptibility was not clear at 15°C. 相似文献
220.
María Eugenia Salgado Salomón Carolina Barroetaveña Mario Rajchenberg 《New Forests》2011,41(2):191-205
We investigated if Pinus ponderosa plantations in Patagonia are able to produce viable mycorrhizal inocula towards adjacent grasslands, which only harbor endomycorrhizal
vegetation. We hypothesized that these inocula have the potential to contribute to the establishment of naturally disseminated
seedlings. Also, we determined the main fungal taxa involved in this process. Seven plantations in the onset of their reproductive
phase and located in the Patagonian native forest/steppe ecotone (Argentina) were selected. Soil samplings were obtained at
nine points along a 450 m long, W-E transect established in each plantation. Soil bioassays were performed in a greenhouse,
with P. ponderosa seedlings acting as hosts for mycorrhizal inocula present in soil samples, during 12 months. Mycorrhization percentage, morphotype
richness and morphotype composition was determined through morphological evaluation. Viable ecto- and ectendomycorrhizal inocula
were found disseminated outside plantations. The amount of mycorrhizal inoculum followed a decreasing function with distance
to plantation edges. Mycorrhizal fungal genus Rhizopogon and “E-strain” mycorrhizal types appeared as pioneering taxa regarding seedlings colonization, being the most persistent
and frequent symbionts found. Plantations, thus, facilitate the surrounding terrain for newcoming seedlings through the dispersion
of mycorrhizal fungal inocula. 相似文献