Foraging site selection behavior by a sit-and-wait predator: the role of biotic and abiotic cues

The placement of spider webs is an excellent model system for the study of habitat utilization by natural enemies, which can have impacts on their effectiveness as biological control agents. However, the behavioral mechanisms driving the selection of web sites by spiders are not fully understood. Field studies have shown that web-building spiders utilize foraging sites with specific structural features and high prey availability. Based on this work, site selection behavior by web-building spiders is thought to be driven directly by micro-habitat structural features, because certain structural features are required to support the web, and these may also provide information about the availability of prey in the micro-habitat. While direct cues from the prey are known to play an important role in the decision to remain in or abandon a foraging site, their role in the initial selection of a site is thought to be minimal. However, behavioral responses to prey cues during initial site selection have not been investigated in web-building spiders. In a laboratory two-choice experiment, sheet-weaving spiders (Araneae: Linyphiidae) were allowed to choose between foraging sites with and without available prey. Spiders showed preference for sites with available prey, both in terms of searching behavior and initial site selection. This study demonstrates that, contrary to current thinking, prey cues do influence the initial selection of foraging sites by spiders. This work has important implications for the study of foraging behavior in sit-and-wait predators, and for the potential impacts of alternative prey on pest-suppression capacity of natural enemies.