Research On Diffusion Rule Of Leptinotarsa Decemlineata Based On GIS In Xinjiang, China

Colorado potato beetle (CPB), Leptinotarsa decemlineata, is an important destructive pest on potato crops worldwide. It was originated in United States or Mexico and invaded into more than40different countries across North America, Europe, Australia and Asia. This invasive pest was dispersed from Kazakhstan into Xinjiang Autonomous Region of China and it was first discovered on potato crops in Ili River Valley area in1993. Since then, it has been widely spread to all over northern of Tianshan Mountain region. CPB has self-independent migration capacity, and reproducable, diapause, near-perfect survival strategy, which make it spread to further east and the risks of invading into Gansu and Inner Mongolia Autonomous Region, the main potato producing areas, are increasing. Meanwhile, it also has an increased risk of the CPB from our neighboring occurred countries spread into Heilongjiang, Jilin provinces in the northeastern China. The diffusion mechanism of alien species in new environment and its interaction between biological and non-biological factors is an important determinant of the spatial distribution pattern and the rate of diffusion. Understanding the relationship of spatial distribution pattern of CPB and environmental factors will be more effective for CPB prevention and control. Therefore, we initiated the study on the diffusion rule of Leptinotarsa decemlineata in Xinjiang. And the purpose of the current study was to understand the role of environment factors in CPB diffusion, and how to more effective to prevent and control of CPB in China. Based on the principle and method of ecological and biological knowledge as well as the use of "3S" information technology, population spatial pattern analysis, as well as temperature, moisture, topography, host, airflow and other factors in its distribution, diffusionin the role of research in order to provide a scientific basis We studied on invasion history of CPB invaded Xinjiang, and spatial pattern of population dynamatic in field. Especially, the relationship of its diffusion and host-plant, temperature, river, air flow and other environmental factors, was major study topics. The research was supported by Special Fund of Agro-Scientific Research in Public Interest (200803024and201103026), the Science and Technology Innovation Foundation for Graduate Students of Southwest University (ky2011007). The study goes well and the main results are summarized as follows:1. Invasion history research and analysis of CPB occurrence in XinjiangIn this study, by the use of ArcGIS software, and combination of biological and ecological characteristics of CPB, space distribution pattern and invasion history of CPB had been successfully obtained in the northern Xinjiang. The results found that the CPB has occurred in35counties and cities of the northern region of Xinjiang in China since1993invasion. The forefront of CPB distribution remains in west of Sangequanzi village, Boshitan town. Mori county, its distribution has not been further expanded. By historical research on the origin of CPB invasion reveals its diffusion historical process. In1995, across the the Tacheng Basin is a turning point in the spread of its spread. Meanwhile, in the diffusion process, spatial range expansion speed is more consistent. By the using of ArcGIS software to analysis the damage degree of CPB in2010. the results showed that the region of CPB colonized earily, such as the Qapqal county, Yining county and dissemination diffusion forward areas Qitai and Mori county, were the most serious damaged. The other regions showed moderate or mild damage. At the same time, the desert region nearly200km between Mori and Barkol county was a natural barrier to block the spread of CPB.2. Research on population biology and ecology of CPB in field2.1Population dynamics in fieldThe CPB’s distribution regions in northern Xinjiang of China has been basically stable, as of now, it has been successfully controled in west of Boshitan town. Mori county. Changji Hui Autonomous Prefecture, where is far from the border of Xinjiang and Gansu at about550km. According to the investigation results in2010-2012, there were deep damage by CPB in Qapqal county, Yining city of Yili Prefecture, Wenquan county of Bole Prefecture, Ermin county of Tacheng Prefecture. Altay city of Altay region, Qitai county. Mori county of Changji Prefecture, other regions were less secious damage. And the damage level was just2degree or3degree. In2008-2010, field population dynamics of CPB in Urumqi county was taken, where was frontier distribution region of CPB. The investigation results were:After2008, the damage of CPB was significantly weakened. At the same time,7monitoring stations of CPB was established in Mori county, and CPB occurrence analysis showed that there were no CPB distribution in three monitoring points of east region of the county, while in the four monitoring points near and west of the county, the charactersitic of CPB damage were sporadic, only a small number of larvae. The population density’of CPB in distribution forefront was lower based on the effective integrated control.2.2Analysis of distribution pattern and affecting factors of overwintering CPBIn this paper, the spatial pattern of overwintering CPB was studied by the use of1DW interpolation tools in ArcGIS software. The overwintering CPBs were collected near in potato emergence point after unearth and they usually go to find host-plants nutritional supplement, and there was an aggregation trends. It was closely related to air temperature and soil moisture during the overwintering adult unearthed period. And with low temperature and low humidity conditions were discourage its emergence significantly. The rise of temperature in spring was directly related to CPB unearth. And the soil temperature usually had an impact on adult survival rate. When spring (April) temperature was stabilized at above15℃, overwintering adults began to unearthed, and the amount of daily emergence was changed with the variation of daily mean temperature fluctuations. Besides, it was also affected by rain, the water, include precipitation and irrigation water during unearthed time, which had an significant relationship of soil temperature and humidity. Soil moisture in the depth of10-20cm, has a direct impact on CPB unearthed. Too high or too low were neither not helpful for overwintering adults unearthed.2.3Diffusion rule of CPB adults in field’With the use of "mark-release-recapture" method, diffusion characterisc of CPB adults of different generations were studied in a potato field in2012. The diffusion speeds of overwintering generation and second generation adults were significantly higher than the first generation of CPB, and there was no significantly difference between the overwintering generation and second generation adults. In the difference of gender of CPB, female CPB spread more quickly than male ones, the volecity of female was2.64±0.25m/d, and the male was1.33±0.28m/d. On the direction of diffusion, the CPB adults diffused slowly on the direction of more insects recapture.3. Key factors impact on spatial distribution pattern of CPBCombine with the distribution data of CPB in current occurrence regions and their24of geographical environment factors, four key main factors:temperature, moisture, terrain and human activity were choosen to analysis.Temperature factor:Combined with the historical climate data of Xinjiang, spatial analysis function of ArcGIS software was used to create a distribution map of the daily mean maximum temperatures of the Xinjiang in summer. With the increasing of temperature, the eclosion rate of CPB larvae was gradually decreased, and the developmental duration was gradually extended. When the temperature reaches39℃, the emergence rate approached zero, the critical high temperature of CPB eclosion tolerance was39℃, and at the same time, the tolerance duration at the temperature of39℃was72h. Summer temperature in Turpan area can rise above39℃and last for more than a month. The extremely heat prevents CPB from colonizing in local areas and limits CPB’s dispersal eastward. It is necessary, however, to strengthen the inspection and quarantine measures to prevent spreading of CPB eastward through human-facilitated transmission. This precautionary measure is critical for the sustainable production of potatoes and other Solanaceae crops. The winter low temperature and soil temperature for the outcome of the CPB overwinter stagnation sterile play a key role, if the days of soil temperature is below-8℃more than10days, it will affect CPB overwintermg.Moisture factor:the CPB existing area of distribution of annual precipitation is about200mm, first discovered the CPB colonization areas precipitation, with direction from west to east, the proliferation of annual precipitation began to reduce. The annual precipitation is less than200mm in Mori county, east of Barkol, Hami in eastern Xinjiang region. The southern border areas precipitation is lower. Reduced rainfall lead to lack of water has a certain role in restricting the spread of CPB distribution.Topographical factors:the barrier effect of the Tianshan Mountains in the Xinjiang region, the CPB distribution was limited to narrow mountain and piedmont shallow mountain belts or plain areas. Distribution by altitude and terrain factors, at the same time. Tianshan barrier effect was further eastward spread of natural barriers. Its spatial distribution in different altitude ranges, according to the characteristics of Xinjiang topography, CPB mainly distributed in concentrated area at an altitude of more than1400m. The current of CPB distribution was affected by altitude and other topographical factors, the effect of Tianshan barrier will be cutted off CPB "s further eastward.Host plant factor:Our study focused on:i) examining the appeal of different host plants to CPB adults in the laboratory; ii) CPB consumption levels during different development stages, including four larval instars and adults; and iii) a field survey of host selectivity among different host plants. The results indicated that there were significant differences (p<0.001) in attraction among the four plants. In order of appeal to CPB, they were (from highest to lowest):potato>henbane>eggplant>tomato. Significant differences (p<0.001) also existed among the four plant species in the amount of leaf consumption by CPBs. Consumption levels were ranked as follows (from highest to lowest):potato>henbane>eggplant>tomato. The field host-selectivity survey also found significant differences (p<0.01) among the four host plants; there were many more CPBs in fields of henbane and potato than in fields of eggplant and tomato. Based on the combined results of these laboratory and field experiments, we concluded that potato and henbane are the most suitable host plants for CPBs, consistent with an analysis done in the first year of their invasion of China in the1990s.4. Analysis of river and the atmospheric circulation on the spread of CPB based on GISAs the CPB spread along riparian habitats from south to north, the damage degree of impact gradually declined, so that the northern towns and those areas received less impact. The Directional Distribution (Standard Deviational Ellipse) tool of ArcGIS was used to determine whether its distribution of the CPB exhibits a directional trend while it compared with the river flow in Shawan county. The results suggested the spread direction of CPB and the river flows coincide; which were both go from south to north. The damage levels from CPB were documented by calculated a series of nested buffer zones. The series of five1-km-wide nested buffer zones were created along Manas rivers in study area. The results showed that CPB damage was significantly different in each buffer zone:buffer zone2> buffer zone4> buffer zone5>buffer zone1>buffer zone3. Habitats along rivers also showed significantly different impacts from CPB:Jinggou River> Anjihai River> Manas River> Xi’an Canal.The direction and velocity of airflow were analysised in northwest and northeast China from April to September in2009in850hPa with the method of atmospheric background field analysis by using GrADS software. The results showed that:in northwest China, the direction of airflow was from west to east only in seldom season, and its velocity was too slow to carry CPB diffusion, as a result, the air flow was not considered as a type of CPB spread and it does not lead to CPB diffuse into the Hexi Corridor in Gansu from its current frontier distribution regions-Boshitan Town, Mori county. In northeast China, during the spring and autumn, the direction of airflow was the same as the direction of CPB invade into China. It was helpful for CPB diffusion from the coastal region of Russia into Heilongjiang and Jilin Province, northeast China. At the same time, the direction of air flow was suitable with the CPB migratory into China, and the wind speed of airflow was also very strong, with the help of airflow, the CPB was able to invade into China. It is important to strengthen the monitoring of the epidemic effectively strong potato cultivation in the region of Heilongjiang border areas.In summary, combined with the biological and ecological characteristics of the CPB. and use of ArcGIS software, this dissertation studied on the relationship between population spatial distribution patterns and environmental factors in Xinjiang. Clear the overwintering generation adults’distribution rule was aggregated after the emergence, as well as the impact of soil temperature, moisture content, and precipitation in spring on overwintering unearthed time and daily amounts. And based on investigation of CPB populations in the northern region, invasion history of CPB and its diffusion mechanisms were knowed. Be controlled in Xinjiang was interaction of temperature, moisture, topography, host plant. Geographical barrier of the Tianshan Mountains and lack of host plants caused CPB’s diffusion was temporarily interrupted. But with the help of the river flow, as well as human activities and other external factors, CPB self-diffusion in the northeast China region in view of the activities of the air flow was significantly stronger in the northwest region. By the facts, monitoring and forecasting of CPB should be earnestly strengthened in northeast China than northwest in China. CPB was ability to further spread eastward into the Hexi Corridor in Gansu Province is unlikely. The results of this study to further clarify the CPB potential distribution of the scientific basis as well as the mechanism of environmental impact, as well as the comprehensive prevention and control.