Risk Assessment On Alien Invasive Species And Construction Of The Risk Analysis Framework

Scientific Risk analysis on alien invasive species (AIS) is a first crucial step in constructing an early-warning system and preventing biological invasions. On the basis of the several sequential transitions in the biological invasion process, Solenopsis invicta, Erwinia amylovora and Bactrocera dorsalis were considered as pattern organisms and risk assessments were implemented.Monte-Carlo simulation was used for the evaluation of the risk probabilities of invasion of the fire blight disease caused by Erwinia amylovora via imported apple fruits by considering that the proportion of infected fruits varying on the production area and the year. Four beta distributions were established to describe the probability distributions of the proportion of infected fruits for 4 different scenarios, respectively. Pert distributions were employed for estimation of the numbers of the imported apple fruits. The estimation of the expected invasion time was 14 years in the fourth scenario, in which described there were no phytosanitary requirements for fire blight. The invasion risk increased with the gain of the imported number.By using geographic information system (GIS), potential establishment areas of Solenopsis invicta Buren in China were predicted. Days above the threshold temperature, the number of degree-days, annual precipitation and altitude were used as the main factors determining its distribution. The potential establishment area was divided into four categories, namely the most suitable area, suitable area, mildly suitable area, and unsuitable area by utilizing the spatial interpolation function in GIS software.Based upon the knowledge of Erwinia amylovora's biophysical characteristics and environmental data, GIS has been applied to determine areas where Erwinia amylovora can potentially invade China where the pest has not been introduced. Temperature and precipitation, during the blossoming period, are considered to be two critical factors affecting Erwinia amylovora's suitable climatic zones. This spatial modeling approach was validated from a case study in Europe, where the occurrence has been proven. The model prediction agreed with the occurrence of the bacteria recorded in Europe and the same procedure has been applied to produce a potential establishment area in China's two preferential apple cultivation regions, Bohai Bay region and Huangtu Altiplano region. It has been found that areas belonging to the high-risk category are more or less the main apple producing areas, accounting for their great economic importance in China.On the basis of the data about current distribution of Bactrocera dorsalis in China and 14 environmental and geological covariates in Asia region, the resulting GARP geographic predictions were exported as ASCâ…¡raster grid files into ArcGIS9.0 for further analysis. Projections for Bactrocera dorsalis to Asia indicate that some Asian countries and regions correspond closely with the known worldwide distribution regions where EPPO (European and Mediterranean Plant Protection Organization) has reported. Using the same sets of ecological dimensions and taking into account the model agreement, the ecological niche model was projected onto the landscape of provinces, municipalities and separate counties in China. Host fruit plants are cultivated with high densities in both suitable and sub-suitable establishment areas of Bactrocera dorsalis.To assess the risk of geographic range extension of Erwinia amylovora, we present a predictive approach based on current climate to determine areas where fire blight can potentially invade in the world by using climate matching software (CLIMEX Version 2.0). Geographic data of Erwinia amylovora were used to fit parameters in risk assessment model. The model prediction agreed with the field observations recorded in the United States and Europe, and allowed us to apply the same procedure to produce maps of the potential risks for the world. Values for the ecoclimatic index (EI), a measure of overall climatic suitability, were between 0 and 100. The CLIMEX model suggests that it could extend its range into temperate regions throughout Asia, Africa, Australia, Oceania and South America, indicating a substantial threat to the country's apple production.General theoretics, patterns and technical principles were extracted from above risk assessments and different risk assessment scheme on biological invasions were constructed concerning pathogens and insects. An early-warning technology and risk assessment protocol were produced, providing scientific foundation for constructing AIS informational management system, listing potential problematic black/grey/white pest catalogues and implementing comprehensive quarantine measures.