Prey selection by generalist predators can be highly dynamic depending on the prey community structure. However, the dynamics of prey selection at the stage of prey entrapping are rarely investigated in trap-building predators, probably because their traps have been previously considered to intercept mobile prey proportionally to its availability in environment. Here we investigated the dynamics of prey selection by the orb-weaving spider Gasteracantha hasselti (Araneidae) depending on the composition of the available prey in tropical lowland forests located in north-eastern Thailand. We found that Gasteracantha captured a wide variety of prey but selected, on average, mostly Coleoptera and Diptera. The selectivity of Gasteracantha’s webs for Coleoptera was constant across the changes in overall prey availability and prey composition. The web selectivity for Hemiptera decreased rapidly with increasing relative densities of Hemiptera in the environment. The selectivity for Diptera and Hymenoptera increased and decreased, respectively, with their absolute densities in the environment. The relative selectivity of Gasteracantha’s traps for a particular prey type was driven by the presence and density of the highly selected prey rather than overall prey density. The results show that the selectivity of Gasteracantha’s traps for prey had both fixed and dynamic components and the dynamic component was determined by the relative as well as absolute densities of the particular prey types in the environment.

中文翻译：

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捕食者 Gasteracantha hasselti 的猎物选择动态

通才捕食者对猎物的选择可能是高度动态的，具体取决于猎物群落结构。然而，捕食阶段的猎物选择动态很少在构建陷阱的捕食者中进行研究，这可能是因为他们的陷阱以前被认为可以拦截与其在环境中的可用性成比例的移动猎物。在这里，我们研究了圆织蜘蛛选择猎物的动态鹅掌楸（蜘蛛科）取决于位于泰国东北部的热带低地森林中可用猎物的组成。我们发现虎斑鱼捕获的猎物种类繁多，但平均而言，主要是鞘翅目和双翅目。的选择性虎斑鱼在整体猎物可用性和猎物组成的变化中，鞘翅目的网络是不变的。随着环境中半翅目相对密度的增加，半翅目的网选择性迅速下降。双翅目和膜翅目的选择性随着它们在环境中的绝对密度而分别增加和减少。相对选择性虎斑鱼特定猎物类型的陷阱是由高度选择的猎物的存在和密度驱动的，而不是整体猎物密度。结果表明，选择性虎斑鱼的猎物陷阱既有固定成分也有动态成分，动态成分由环境中特定猎物类型的相对密度和绝对密度决定。