Risky behaviors by the host could favor araneophagy of the spitting spider Scytodes globula on the hacklemesh weaver Metaltella simoni

Abstract

Versatile predatory tactics might favor success during intra-guild predation. In the case of spiders, the preditory spitting spiders (Scytodidae) invade webs and feed on certain weaver spiders. Based on preliminary observations of Scytodes globula, we tested if this spider species as predator could feed on the sympatric hacklemesh weaver Metaltella simoni (Amphinectidae) as host, or if the host spider could prevent the attack. We exposed adult females of M. simoni on 2-week-old webs to adult female spitting spiders. The spitting spider preyed on the host spider in 28 % of the 72 trials in which the two spider species interacted. Leaving the retreat, approaching the predator, and touching the invader apparently made the host spider vulnerable to predation in 55 % of those interactions; therefore, those were considered risky behaviors. To the contrary, the host spider had a success rate of 67 % of surviving predation by performing defensive behaviors (moving hind legs, performing defensive displays). In four trials, the invader performed a defensive spit to deter the attack of the host spider, which points to the versatility of this trait. We found no effect of body size ratio of the spiders on the outcome of the interactions. The host spider left the retreat after the spitting spider entered its web, suggesting that the spitting spider could be performing aggressive mimicry, but notion is supported by only indirect evidence and needs further exploration. In summary, behavioral interplay mediated the outcome of the interactions between the two coexisting predators assessed in our study.