烟稻轮作对入侵生物福寿螺的生态毒理效应及控制机制

Golden apple snail Pomacea canaliculata (Lamarck 1822), is a cosmopolitan harmful alien invasive species. It was introduced to China for nearly four decades and has caused incalculable rice production losses in the south China. Botanical molluscicide as an environmental friendly technology for controlling P. canaliculata, has drawn worldwide attention in academia. Nicotine is richly contained in tobacco Nicotiana tobacum and as an important potential resource for molluscicide manufacturing, as well as an autotoxin in tobacco continuous cropping, so implementing tobacco rotation is an important measure to ensure sustainable development in tobacco field. Besides, our previous studies showed paddy-upland rotation is an effective way to reduce the amount of P. canaliculata in rice field. Then, relative to general rice-vegetable rotation, whether rice-tobacco rotation has better performance in controlling P. canaliculata through dual functions of dry-farming and nicotine? To our knowledge, the research about rice-tobacco rotation on control of P. canaliculata has never been reported. For this, we plan to employ indoor simulation experiments, field-plot experiments and follow-up field survey to study the ecotoxicological effects of tobacco residue decomposition, root exudates, tobacco extracts and nicotine standard on P. canaliculata, based on the responses of the snails in survival, growth, reproduction, behavior, morphology and physiology. Meanwhile, in-situ control effects and mechanisms of rice-tobacco rotation on field populations of P. canaliculata will be explored, which would provide basic information and scientific basis for development and application of correlation techniques.

福寿螺作为一种世界性入侵生物，引入我国近40年，对南方水稻生产造成严重危害。植物源杀螺剂作为一种环境友好型技术，受到国内外研究者的广泛关注。烟草中烟碱含量丰富，是制造杀螺剂的重要潜在资源，同时亦是引发烟草连作障碍的自毒物质之一，故进行烟草轮作是保证烟区可持续发展的重要措施。此外，我们前期研究表明，水旱轮作能够有效减少稻田福寿螺的发生量。那么，相对于常规稻菜轮作模式，烟稻轮作能否通过“旱作”和“烟碱”双重作用实现更佳的控螺效果？目前，国内外尚未见有关烟稻轮作控制福寿螺的研究报道。为此，本项目拟通过室内模拟实验、野外大田小区试验和实地跟踪调查，基于福寿螺生存、生长、繁殖、行为、形态和生理响应，探究烟草残体腐解物、根系分泌物、烟草浸提液和烟碱标品对福寿螺的生态毒理效应，以及烟稻轮作对稻田福寿螺种群的原位防控效果及作用机制，旨在为后续开展相关技术的研发应用提供基础资料及参考依据。

外来入侵生物福寿螺对我国南方水稻生产造成严重危害，水旱轮作是控制稻田螺害的重要手段之一。考虑到烟草中富含的烟碱是传统的植物源杀虫剂，为此我们通过室内模拟实验、田间小区试验和野外调查探究了烟稻轮作对稻田福寿螺种群的控制效果及作用机制。研究表明：1）烟稻轮作能够显著降低稻田福寿螺的发生量，并能提高水稻产量，且效果优于大豆-水稻轮作、玉米-水稻轮作；2）烟草浸提液能够有效抑制福寿螺的发生，抑制效果从强到弱依次是烟叶、烟梗、烟茎、烟根；3）烟叶浸提液对成螺的毒杀效果强于幼螺，对成年雄螺的毒杀效果强于雌螺，1 g/L烟叶浸提液可致使90%以上的福寿螺在4 d内死亡，0.5 g/L烟叶浸提液下福寿螺难以摄食和交配，0.2 g/L烟叶浸提液即可致使福寿螺繁殖显著受抑制；4）烟叶可直接风干粉碎还田，用量达1-2 g/L时可取得显著杀螺效果，且不会抑制水稻苗的正常生长；5）烟叶腐解物能够有效控制福寿螺危害，但不宜选择鲜叶腐解，其可能抑制水稻苗生长；6）烟草根系分泌物能够有效毒杀福寿螺，但只能起一定的辅助作用；7）烟草和生石灰复配表现出优于单一使用烟草或生石灰的杀螺效果，复配比例为4:1时，杀螺效果最优；8）烟草有机固态肥和水溶肥在推荐用量范围内均能有效毒杀福寿螺；9）相对于其他茄科作物，福寿螺对烟叶有取食偏好性，但取食烟叶可能导致螺死亡。研究结果表明烟稻轮作能通过“旱作”和“烟碱”双重作用实现较常规稻菜轮作更佳的控螺效果及烟草废弃物可作为潜在植物源杀螺剂开发利用。