Influence of past and current social contexts on hunting behaviour in spiderlings

When foraging in a group, individuals adjust their behaviours to the actions of others in order to optimize their pay-offs. While many studies have examined the influence of group composition on behavioural strategies, relatively few have investigated how the presence or absence of conspecifics influences the expression of behaviours during hunting. Another aspect that has received little attention concerns the impact of prior social experience on the expression of predatory behaviour. Here, we studied how past and present social contexts influenced predatory behaviour in juveniles of the spider Agelena labyrinthica which, like most solitary species, exhibit a transient gregarious phase prior to dispersal. We tested, alone or in pairs, spiderlings that have been maintained in isolation or in groups for 24 h prior to behavioural assays. During the tests, we introduced a live prey to an experimental arena and we measured the latencies associated with the different phases of the hunting sequence. We found that spiders maintained in isolation captured prey faster than those kept in groups and that the presence of a sibling increased the latency of prey capture compared with individuals hunting alone. Such a social context effect adds another dimension to the already complex combination of factors that determine the success of spider foraging. Overall, our study reveals an influence of the social dimension, past and present, on hunting behaviour that may have been underestimated in carnivores. SIGNIFICANCE STATEMENT: It is generally considered that hunting in group increases individual benefits compared with solitary hunting. However, relatively few studies have compared hunting performance between individuals hunting alone or in group to assess how the presence of conspecifics impacts the expression of predatory behaviours. Another aspect that has been little explored concerns the role of the social context previously experienced on hunting behaviour. This study examined the influence of past or present social context on hunting behaviour in juveniles of a solitary spider during their gregarious phase. We showed that spiderlings maintained in isolation or tested alone were faster at catching prey than congeners reared socially or tested in groups. This study highlights a cost to sociality that has so far received little attention, and which could be an important element to consider in understanding transitions to permanent sociality.