Behavioral manipulation of the orb-weaver spider Argiope argentata (Araneae: Araneidae) by Acrotaphus chedelae (Hymenoptera: Ichneumonidae)

We observed the first case of host-behavioral manipulation of an orb-weaver spider Argiope argentata induced by a parasitoid wasp of the genus Acrotaphus. The modified web is similar of those constructed by other orb weavers attacked by wasps of the close related genus Hymenoepimecis. The stick spirals and radii are absent and the web is composed of a three-dimensional structure of non adhesive threads. The discovery of the ability to induce changes in host's web-building behavior in Acrotaphus is indicative that this trait may be primitively present in the clade that includes the genus Hymenoepimecis.