福寿螺地理种群的耐寒性及其在中国的适生区预测

The golden apple snail [Pomacea canaliculata (Lamarck)], a worst exotic invasive pest introduced in southern China around 1980s, is gradually expanding its range into the country's northern areas in recent years. Temperature, especially low temperature, is a major influential factor for survival, distribution, reproduction and spread of the apple snails. However, currently there is no detailed information on low- temperature adaptability, northern extending boundary and overwintering mechanism of the apple snails. In this study, effects of temperature fluctuations, photoperiod- temperature changes, soil temperature-moisture conditions, feeding-plant species, mating behavior on supercooling point, nutrients content and activity of the protective enzymes for the apple snails will be examined in laboratory. Differences in cold resistance ability of geographic populations, gender and developmental stages of the apple snails will be investigated, with the aim of revealing the influential factor for successful overwintering as well as strategies of cold acclimation and winter hardiness. On this basis, the bioclimatic niche model (CLIMEX), maximum entropy model (Maxent), regional system dynamics model (STELLA), along with geographic information system (GIS) techniques will be employed from different scale space to explore the suitable geographic distributions of the apple snails. Model predictions will be assessed by field experiments and surveys. Moreover, models under present conditions will be projected using three general circulation models (GCMs) under two types of representative concentration pathways (RCP 4.5 and RCP8.5) to examine variations of northern overwintering boundary, annual number of generations and the area changes in overwintering regions in two periods (2020s, 2050s). The results will provide valuable information for assessing the risk of apple snails pose to China and for prioritizing early detection and prevention strategies.

福寿螺是当前入侵我国华南地区并逐渐向其以北地区扩散的外来有害生物。温度尤其是低温，是影响福寿螺发生、分布、繁殖和扩散的重要环境因素，但目前对福寿螺的低温适应性、扩散北界及越冬机制等缺乏系统性研究。项目通过温度波动、光周期-温度、土壤温湿度、食物、越冬前交配影响福寿螺过冷却点、营养物质含量以及保护酶活性等的试验，剖析不同地理种群、性别和螺态的福寿螺耐寒能力的差异，揭示福寿螺越冬的影响因素及低温适应的行为、生理生态学策略。在此基础上，利用生物气候模型（CLIMEX）、最大熵模型（Maxent）、区域性福寿螺种群动态模型（STELLA）并结合GIS 技术，从不同的空间尺度研究福寿螺在我国的适生性，并经田间试验和实地调查加以验证。研究也将结合多情景、多模型以及多时段的未来气候数据，预测未来福寿螺的越冬界限、发生世代和扩散趋势，以期为福寿螺的生态风险评估、防控策略的制定等提供科学依据。

福寿螺是入侵我国华南地区、对水稻及其他水生植物及水体环境产生严重危害的外来淡水螺类软体动物。温度尤其是冬季低温是福寿螺种群发生、分布和扩散的关键因素。本项目选择了5个福寿螺入侵区的稻田生境为研究区，设计了5个福寿螺耐寒性室内控制实验、1个自然条件下的越冬及出土情况调查方案及适生性研究方案，从形态学、解剖学、行为学和生理生态学等角度研究了福寿螺种群在控制条件和野外环境下对低温的适应策略，明确了不同地理种群、性别及螺态的福寿螺耐寒性的差异，揭示了福寿螺低温适应和越冬的生理生态学策略。另一方面，项目以福寿螺信息数据库为基础，借助生物分布预测模型和GIS技术，明确了福寿螺在我国的越冬北界及适生范围，预知未来气候情景下福寿螺的扩散趋势及适生区变化。结果发现，入侵我国的福寿螺已经形成了不同温度耐受性的地理种群。福寿螺的耐寒性是多种因素如地理环境、气候的季节性变化、食物因素、越冬生境等作用的结果。这些环境因素与福寿螺的发育阶段、生物学状态等因素对福寿螺耐寒性的影响最终都是通过干扰福寿螺螺体含水量、耐寒性生理物质的组成及转换等来实现的。福寿螺在我国存活、爆发的地点范围在南方多个省份呈现向周边地区不断扩散的态势。预计到2050年，适宜福寿螺种群繁殖及越冬的区域范围将扩大，最南端的适宜程度有所减弱，而地处长江流域中、东部的大片地区的适生程度增强。与越冬福寿螺种群相比，适宜福寿螺种群繁殖的区域范围预计将进一步向北延伸至四川盆地西部边缘和河南部分地区。此外，研究证实了小管福寿螺和斑点福寿螺在入侵过程中无环境生态位漂移的情况发生，且处于较为稳定的状态。.项目已发表科研论文共13篇；获授权发明专利2项；软件著作登记权2项；提交了福寿螺为害及防控相关的调研报告共2份。研究结果为福寿螺综合防控措施的制定、生态风险评估和预警等提供了重要基础资料，也为了解和掌握福寿螺的越冬北界及扩散规律提供了科学参考。