RESUMO
@#Abstract: Objective To understand the changes of newly emerging and re-emerging snail areas in Anhui from 2017 to 2021 and analyze its related influencing factors, so as to provide scientific basis for formulating snail control strategies. Methods According to the historical snail survey data, the information of newly emerging and re-emerging snails from 2017 to 2021 were collected, the causes for the formation of newly emerging and re-emerging snails flourish environments were investigated and analyzed retrospectively. Results During 2017-2021, in Anhui, the area with newly emerging snails was respectively 840.41 hm2, 559.14 hm2 (66.53%) in lake and marshland areas and 281.27 hm2 (33.47%) in hilly areas; the area of re-emerging snails was respectively 1 176.87 hm2, 669.39 hm2 (56.88%) in lake and marshland areas and 507.48 hm2 (43.12%) in hilly and mountainous areas. The sum of newly emerging snail area in Chizhou, Anqing and Wuhu accounted for 89.35% of all, the sum of re-emerging snail area accounted for 88.82%. In 2021, the areas with newly emerging and re-emerging snails peaked at 611.52 hm2 and 976.84 hm2, respectively. The newly emerging and re-emerging snail habitats were mainly distributed in the transmission interruption areas, accounting for 65.54% and 84.30%, respectively. The newly emerging and re-emerging snail habitats were mainly found in fluvial marsh, accounting for 65.54% and 52.12%, respectively. In recent 5 years, the longest time interval of re-emerging snails was more than 50 years. The main causes of newly emerging snails were natural factors such as flood disaster and snail drift along river system. Natural factors, such as flood disaster and snail drift along river system, were the main reasons for the newly emerging snail habitats, accounting for 71.44% and 21.75%, respectively. Human factors, such as soil extraction from snail habitats, construction of water conservancy facilities, farmland abandonment and seedling transplanting, could also lead to the newly emerging snail habitats. Flood disaster was the main cause of re-emerging snail habitats, accounting for 72.29%. In addition, the re-emerging snail habitats were caused by historical snail residue, soil collection in snail habitats for construction projects, land abandonment, seedling transplanting, prohibition of snail control in ecological protection areas, and construction of water conservancy facilities. Conclusions Flood disaster is an important factor for snail newly emerging and re-emerging. Human factors such as engineering construction and seedling transplanting are also easy to cause snail newly emerging and re-emerging. In order to timely detect and deal with newly emerging and re-emerging snail habitats and prevent snail diffusion, it is necessary to investigate snail distribution after flood disaster, the routine monitoring of historical snail habitats should be strengthened; in engineering construction and seedling transplanting, the disposal of soil with snails should be done well.
RESUMO
Crepidiastrum sonchifolium, a flowering plant in the daisy family (Asteraceae), is native to East Asia. In Korea, this plant is a locally cultivated vegetable, and its market size is gradually growing. Since the plants with downy mildew infection were initially found at a private farm of Chuncheon city, the occurrences have continued in commercial farms of other regions, highlighting that this disease is spreading throughout Korea. The pathogen was attributed to a member of the genus Bremia that contains many specialized species, each of which displays a narrow host spectrum on Asteraceae. Based on morphological and molecular phylogenetic analyses, along with the high host specificity recently proven for Bremia species, the identity of the causal agent was confirmed as a so far undescribed species of Bremia. Here, we introduce Bremia itoana sp. nov., specific to C. sonchifolium.