Host behavioural manipulation of two orb-weaver spiders by parasitoid wasps

Proximate mechanism of behavioral manipulation of an orb-weaver spider host by a parasitoid wasp

“…morretes , P . janzeni , has been previously reported from Costa Rica [27] and the Brazilian Atlantic rainforest [21,28]. The parasitoid of C .…”

“…To describe the structure of molting, cocoon, and normal webs, we followed [21]. We quantified structural web changes in the field by first covering the webs with water, then photographing them.…”

“…We quantified structural web changes in the field by first covering the webs with water, then photographing them. We evaluated changes in radii and spiral number, which are variables previously utilized to describe web alterations resulting from spider host and larval parasitoid interactions [20, 21]. Molting webs were identified by the presence of exoskeletons adhered to the webs.…”

“…After the spider builds this modified structure, the larva kills its host, and builds its cocoon attached to the silk threads spun by the host. Cocoon webs appear to be more resistant to rupture [18,20,21] and have fewer components (e.g., radii and sticky spirals in orb webs) that are utilized for prey interception and retention. Variations of this general pattern include the addition of barrier threads [22], shorter radii, doubled number of lines in each radius, construction of a reinforced frame [19], reinforcement of the retreat by addition of more threads [14] or a veil sheltering the cavity containing spider and larva [23].…”

“…Variations of this general pattern include the addition of barrier threads [22], shorter radii, doubled number of lines in each radius, construction of a reinforced frame [19], reinforcement of the retreat by addition of more threads [14] or a veil sheltering the cavity containing spider and larva [23]. These alterations are not a by-product of infection [20,21], but appear to be directly induced by the parasitoid larva. This hypothesis is supported by the fact that removing the larva after the construction of the modified web results in the spider gradually building webs that progressively resembles normal webs [19].…”