Intraspecific aggregations and colonial structures in orb-weaver spiders can reduce the per capita amount of silk to be spun, allow the use of habitats which are unavailable for solitary species, and increase protection and foraging efficiency. However, conflicts between colony members can occur during web construction, repair, and prey capture, contributing to group dissociation under conditions of low prey availability and/or in specific stages of spider maturation. While small juveniles are benefited by the joint action of many spiders during prey immobilization, older and large individuals are able to capture all available prey by themselves. For those large individuals, interactions with neighbours may compromise the amount of available resources. In this context, we evaluated the frequency of foraging events involving cooperative hunting and conflicts between residents and intruders in very young and older juveniles of Parawixia bistriata, a colonial orb-weaver spider. We recorded foraging behaviour in natural conditions and identified the main groups of insects intercepted at the webs and captured by the spiders. We then used two prey types (Lepidoptera and Orthoptera), with distinct behaviours when intercepted, in an experiment to test the influence of prey type and mass on cooperative and aggressive interactions. Most captures occurred without the participation of other individuals, and the main prey types were small Diptera and Coleoptera. Cooperative behaviour seems to occur especially between young spiderlings, but depending on prey type and size, it also occurs in late instars. The frequency of conflicts was similar in both periods of observation (November and December), with young and older individuals in colonies. Our results indicate that prey type is an important factor determining the frequency of interactions during foraging events in colonies of P. bistriata and that large spiders usually obtain success in conflicts. We suggest that these conflicts over large items may constitute a relevant variable involved in colony dissociation before spiders’ maturation.

中文翻译：

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在殖民蜘蛛Parawixia bistriata（Araneae：Araneidae）的殖民地捕获猎物期间的合作与冲突

球形编织蜘蛛中的种内聚集和殖民地结构可以减少纺出的人均丝绸数量，允许使用单生种无法获得的栖息地，并提高保护和觅食的效率。但是，在网状结构构建，修复和捕获猎物的过程中，可能会发生群体成员之间的冲突，这在猎物利用率低和/或蜘蛛成熟的特定阶段导致群体解离。在固定猎物期间，许多蜘蛛的联合行动使小型少年受益，而较大的个体则能够自己捕获所有可用的猎物。对于那些大个子，与邻居的互动可能会损害可用资源的数量。在这种情况下，偏竹，一种殖民的球形织布工蜘蛛。我们记录了自然条件下的觅食行为，并确定了在网上被拦截并被蜘蛛捕获的主要昆虫。然后，我们在实验中测试了两种类型的猎物（鳞翅目和直翅目），它们在被截取时具有不同的行为，以测试猎物类型和质量对协作性和攻击性相互作用的影响。大多数捕获发生在没有其他人参与的情况下，主要猎物类型为小型双翅目和鞘翅目。合作行为似乎尤其发生在幼小的幼鸟之间，但是取决于猎物的类型和大小，它也发生在晚熟的幼虫中。在两个观察期间（11​​月和12月），冲突的发生频率相似，殖民地中的年轻人和老年人。P. bistriata和大型蜘蛛通常在冲突中获得成功。我们建议这些大项目上的冲突可能构成蜘蛛成熟之前进行菌落分离的相关变量。