[Studies on colonization risk and potential geographical distribution of as an intermediate host of in Mainland China].

Objective: To predict the colonization risk and potential geographical distribution of in the Mainland China based on the past period temperature data.

Methods: The survival extreme high temperatures and low temperatures of eggs, young and adult snails and the average effective accumulated temperature of generation development were determined in laboratory conditions. The temperature data in January and July from 1955 to 2010 were collected from the national meteorological monitoring sites in the southern part of China, including Chongqing, Zhejiang, Yunnan, Sichuan, Jiangxi, Hunan, Hainan, Guizhou, Guangdong, Guangxi and Fujian provinces (11 provinces). A database of ambient temperature related to was established based on the Geographic Information System (GIS). The colonization risk and potential geographical distribution of in the southern part of China were analyzed and predicted by ArcGIS 10.1 software.

Results: The half lethal low temperatures of eggs, young and adult snails were 6.80, 6.34 ℃ and 6.60 ℃ respectively; the half lethal high temperatures of eggs, young and adult snails were 35.99, 33.59 ℃ and 32.20 ℃, respectively. The developmental threshold temperature was 7.16 ℃; the average effective accumulated temperature of generation development was (1 970.07 ± 455.10) days-degree. The GIS overlay analysis of the half lethal low and high temperatures of showed that the local temperature conditions in all Hainan and part regions in Yunnan, Guangxi, Guangdong and Fujian were conformed to the survival temperature of snails. The regions, where the average effective accumulated temperature was more than the average effective accumulated temperature of generation development of , were Guangdong and Hainan, and part regions of other 9 provinces. The overlay analysis of GIS maps of the survival extreme high temperatures and low temperatures of with the GIS map of the average effective accumulated temperature of generation development in 2010 showed that the whole region of Hainan and part regions of Guangdong, Guangxi, Yunnan and Fujian were potential geographical distribution regions of colonization risk of . The overlay analysis of GIS maps of the survival extreme high temperatures and low temperatures of with the GIS map of the average effective accumulated temperature of generation development from 1955 to 2010 showed that the potential geographical distribution regions of was expanding from the whole region of Hainan and part regions of Guangdong in 1955 to the whole region of Hainan and part regions of Guangdong, Guangxi, Yunnan and Fujian in 2010.

Conclusions: If snails were introduced into the Mainland China, the potential geographical distribution regions would be the whole region of Hainan and part regions of Guangdong, Guangxi and Yunnan. The changes of risk range and risk intensity present the trends of expanding and increasing from the south to the north gradually.