Spiders are important bio-control agents of rice insect pests such as plant- and leafhoppers. To investigate temporal changes in spider prey and variations in prey due to landscape structure around rice fields, carbon and nitrogen stable isotopes of rice field arthropods were analysed over three consecutive sampling dates during the rice cropping season. Initial isotope composition of gnats and midges emerging from submersed rice fields indicates a larval algae diet, while later values suggest a switch to rice-derived carbon. Initial δ13C values of plant- and leafhoppers were higher in fields of rice-heterogeneous landscapes, indicating migration from source populations feeding on C4 grasses into rice fields; later, their δ13C values approached those of rice. Isotope values of web-building and cursorial spiders in the earliest samples indicate aquatic gnat and midge prey. The later shift toward terrestrial herbivore prey was more pronounced for small than for larger species and in rice paddies near permanent vegetation, indicating use of prey from the surrounding landscape. The results suggest that rice field spiders are supported by three different carbon pools: (1) aquatic carbon originating from algae and (2) legacy carbon from previous growing cycles, both incorporated via between-season predation on gnats and midges, and (3) carbon from the current rice season incorporated via herbivore prey. In conclusion, fostering aquatic midge and gnat larvae, e.g. via mulching, and integrating rice fields into rice-heterogeneous landscapes likely strengthens biological control of pest species in rice paddies by supporting high populations of spiders between cropping seasons.

中文翻译：

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稻田生态系统中的蜘蛛从水族转变为陆地猎物，并使用不同来源的碳库。

蜘蛛是水稻害虫如植物和叶蝉的重要生物防治剂。为了调查稻田周围景观结构引起的蜘蛛猎物的时间变化和猎物的变化，在稻作季节的三个连续采样日对稻田节肢动物的碳和氮稳定同位素进行了分析。从淹没的稻田中出现的和mid的初始同位素组成表明其幼虫藻类饮食，而后来的值则表明已转为稻源碳。稻草异质景观田中植物和叶蝉的初始δ13C值较高，表明从以C4草为食的源种群向稻田中的迁移。之后，它们的δ13C值接近水稻。最早样本中的网状构造和游标蜘蛛的同位素值表示水生和mid类猎物。较小的物种比较大的物种以及在永久植被附近的稻田中，后来向陆生草食动物猎物的转移更为明显，表明使用了周围景观的猎物。结果表明，稻田蜘蛛受到三个不同碳库的支持：（1）来自藻类的水生碳和（2）先前生长周期的遗留碳，两者都是通过对between和mid的季节间捕食而结合在一起的；（3）通过食草动物的猎物吸收了当前稻米季节的碳。总之，例如通过覆盖来养殖水生蚊虫和类幼虫，