Wheat blue dwarf disease (WBD) was first reported in China in the 1960s. It has caused severe losses on several occasions in winter wheat (Triticum aestivum) in northwestern China, and the nature of the pathogenic agent has been unknown. Here we have shown that WBD was caused by a 16SrI-C phytoplasma transmitted by Psammotettix striatus. This finding was based on molecular diagnostics, insect transmission trials, and host-range determination. Portions of the 16S rRNA and ribosomal protein (rp) genes, rpsS (rps19), rplV (rpl22), and rpsC (rps3), were amplified from DNA samples of WBD-infected wheat seedlings by polymerase chain reaction (PCR) utilizing phytoplasma specific primer pairs. The nucleotide sequences of these amplicons showed high identity to these genes from phytoplasma strains in the aster yellows group (16SrI). Pairwise nucleotide sequence identities of WBD 16S rDNA compared to representative genes of 16SrI group strains ranged from 98.9 to 99.9%, whereas compared to 17 other phytoplasma groups (16SrII to 16SrXVIII), sequence identity ranged from 88.6 to 96.0%. Similarly, the sequence identities of rps19, rpl22, and rps3 between WBD and 16SrI group strains varied from 96.6 to 99.7%, but only 60.3 to 65% between WBD and other phytoplasma groups. Phylogenetic analyses were carried out on sequences from 16S rRNA and ribosomal protein genes (rps19, rpl22, and rps3), respectively, and both results indicated that WBD phytoplasma was a member of the 16SrI group and most closely related to subgroup 16SrI-C. WBD-infected P. striatus were present in wheat fields with WBD, and phytoplasma infection was verified by PCR detection followed by DNA sequencing. Insect transmission trials confirmed that P. striatus transmitted the WBD phytoplasmal agent from infected wheat to healthy wheat seedlings and seven other different plant species in the greenhouse. A survey of various weed species near WBD-infected wheat fields found 10 plant species in seven families to be positive for the presence of WBD phytoplasma.
Using data from a major online peer-to-peer lending platform, we document that, due to time pressure, investors appear to focus on interest rates and only partially account for credit ratings in their decisions. The effect is stronger for mobile-based investors than for PC-based ones. Our evidence suggests that this variation is caused by the difference in information content on the interfaces rather than differences in the devices’ physical attributes per se. Investors improve their decisions by slowing down and paying more attention to credit ratings after experiencing a loan default firsthand, but not after observing others experiencing defaults.
The purpose of the research presented here was to empirically assess resident perceptions of tourism development around the Changbai Mountain Biosphere Reserve (CMBR), a protected area straddling the China and North Korea border. Several theoretical approaches to the assessment of local resident attitudes towards tourism were reviewed and integrated into a novel factor-cluster assessment of residents in Erdaobaihe, the community most adjacent to CMBR. This analysis quantitatively grouped residents based on their perceptions of tourism’s economic, social, cultural, and environmental consequences for the town. An exploratory factor analysis of resident perceptual items first revealed six perception domains, and a subsequent cluster analysis then identified four distinct groups of residents based on these perceptions. A descriptive profile of each cluster and the significant differences among clusters are provided. Advancing our theoretical understanding of resident perspectives of tourism development, this cluster-based segmentation approach, demonstrated here, holds much promise for elaborating on the many ways that residents respond to new and long-standing forms of tourism in their communities. These theoretical and methodological contributions will be applicable to scholars as well as tourism practitioners and policy makers.
Nature-based tourism attractiveness (NBTA) has yet to be assessed by coupling empirical measurement of supply and demand indicators with simultaneous assessment of tourist and tourism expert perspectives. Based on a guiding principle that the overall attractiveness of a tourism destination should combine the evaluation of existing resources or attractions and their perceived attractiveness, the purpose of this study is to develop and apply a novel methodological approach for assessing tourism attractiveness of nature-based destinations. This approach developed here combines an Analytic Hierarchy Process (AHP) with a Fuzzy Comprehensive Evaluation Method (FCEM). The resulting Fuzzy-AHP approach to NBTA was tested at the Changbai Mountain Biosphere Reserve, a popular nature-based tourism destination in China. The findings confirm that this Fuzzy-AHP approach is a more reliable and comprehensive method for evaluating the destination attractiveness than pre-existing approaches. In addition to theoretical contributions related to the merging of various approaches to assessing destination attractiveness and the development of a tool specific to nature-based tourism destinations, this work will be of interest to decision makers seeking more effective tools for planning, marketing, and developing nature-based tourism destinations.
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