Data from: Simplifying understory complexity in oil palm plantations is associated with a reduction in the density of a cleptoparasitic spider, Argyrodes miniaceus (Araneae: Theridiidae), in host (Araneae: Nephilinae) webs

Expansion of oil palm agriculture is currently one of the main drivers of habitat modification in Southeast Asia. Habitat modification can have significant effects on biodiversity, ecosystem function, and interactions between species by altering species abundances or the available resources in an ecosystem. Increasing complexity within modified habitats has the potential to maintain biodiversity and preserve species interactions. We investigated trophic interactions between Argyrodes miniaceus, a cleptoparasitic spider, and its Nephila spp. spider hosts in mature oil palm plantations in Sumatra, Indonesia. A. miniaceus co-occupy the webs of Nephila spp. females and survive by stealing prey items caught in the web. We examined the effects of experimentally manipulated understory vegetation complexity on the density and abundance of A. miniaceus in Nephila spp. webs. Experimental understory treatments included enhanced complexity, standard complexity, and reduced complexity understory vegetation, which had been established as part of the ongoing Biodiversity and Ecosystem Function in Tropical Agriculture (BEFTA) Project. A. miniaceus density ranged from 14.4 to 31.4 spiders per square meter of web, with significantly lower densities found in reduced vegetation complexity treatments compared with both enhanced and standard treatment plots. A. miniaceus abundance per plot was also significantly lower in reduced complexity than in standard and enhanced complexity plots. Synthesis and applications: Maintenance of understory vegetation complexity contributes to the preservation of spider host–cleptoparasite relationships in oil palm plantations. Understory structural complexity in these simplified agroecosystems therefore helps to support abundant spider populations, a functionally important taxon in agricultural landscapes. In addition, management for more structurally complex agricultural habitats can support more complex trophic interactions in tropical agroecosystems.

当前，油棕种植业的扩张是东南亚地区生境改造的主要驱动因素之一。生境改造可通过改变生态系统中的物种种群密度或可利用资源，对生物多样性、生态系统功能以及物种间相互作用产生显著影响。改造后的生境若提升其复杂性，则有望维持生物多样性并保护物种间的相互作用。
我们在印度尼西亚苏门答腊的成熟油棕种植园中，探究了盗寄生蜘蛛Argyrodes miniaceus与其寄主络新妇属（Nephila spp.）蜘蛛之间的营养相互作用。该蜘蛛会寄居在雌性络新妇属蜘蛛的蛛网中，并通过窃取蛛网内捕获的猎物存活。我们研究了人工调控林下植被复杂性对络新妇属蜘蛛蛛网中Argyrodes miniaceus种群密度与个体丰度的影响。本次实验设置的林下植被处理组涵盖复杂性提升组、常规组与复杂性降低组，所有处理组均隶属于正在推进的热带农业生物多样性与生态系统功能（Biodiversity and Ecosystem Function in Tropical Agriculture, BEFTA）项目。
Argyrodes miniaceus的种群密度范围为每平方米蛛网14.4至31.4只，其中复杂性降低处理组的种群密度显著低于复杂性提升组与常规处理组。各实验样地内Argyrodes miniaceus的个体总数同样在复杂性降低处理组中显著低于常规组与复杂性提升组。
总结与应用：维持林下植被复杂性，有助于保护油棕种植园中的蜘蛛寄主-盗寄生者关系。在这类简化的农业生态系统中，林下结构复杂性有助于维持丰富的蜘蛛种群——蜘蛛是农业景观中具有重要生态功能的类群。此外，通过构建结构更复杂的农业生境，可助力热带农业生态系统中更复杂的营养相互作用的维持。