Age-dependent stabilimentum-associated predator avoidance behaviours in orb-weaving spiders

In this study, we investigated stabilimentum-associated predator-avoidance behaviours of an orb-weaving spider, Argiope versicolor, by addressing two questions: (1) Is there any difference in predator-avoidance behaviour between juveniles and adults? (2) Is a predator-avoidance behaviour stabilimentum-specific? Two types of artificial stimuli, tactile stimulation and air movement, were used, and both elicited four avoidance behavioural responses in A. versicolor: 'shuttling', 'pumping', 'dropping', and 'shifting'. Overall, juveniles were more likely than adults to respond to the stimuli. Adults frequently responded to disturbance by dropping and pumping, whereas juveniles by shuttling and shifting. More importantly, A. versicolor adopted stabilimentum-specific predator-avoidance tactics. Juveniles shuttled more often on discoid-stabilimentum-decorated webs than on undecorated webs, whereas adult females dropped from undecorated webs more frequently than from cruciform-stabilimentum-decorated webs. Moreover, adults pumped their webs more often on webs with cruciform stabilimenta than on webs without cruciform stabilimenta.