Predatory chemical cues decrease attack time and increase metabolic rate in an orb-web spider

ABSTRACT Animals are able to assess the risk of predation and respond accordingly via behavioural and physiological changes. Web-building spiders are in the unique situation where they reside in the middle of their web and are therefore relatively exposed to predators. Thus, these spiders might moderate either their web-building behaviour or their behaviour on the web when exposed to the threat of predation. In this study, we experimentally explored how chemical cues from a predator influence foraging behaviour and metabolic rate in females of the orb-web spider Argiope keyserlingi. We found that female spiders restricted their foraging time budget when exposed to the predator cues from a praying mantid: they responded 11% and 17% quicker to a vibratory stimulus compared with control and non-predator cues, respectively, and spent less time handling the prey. Moreover, spiders were less likely to rebuild the web under predator cues. Female A. keyserlingi exposed to the praying mantid cue significantly elevated their metabolic rate compared with the control group. Our findings revealed short-term modifications over the 2 week trials in foraging behaviour and the physiology of female spiders in response to predator cues. This study suggests that under predator cues the spiders move quicker and this could be facilitated by elevation in metabolic rate. Reduced foraging activity and less frequent web repair/rebuilding would also reduce the spiders9 exposure to praying mantid predators.