Effects of phytochemicals on predatory decision making in a spider

Animals with small nervous systems may be prone to limitations in processing ability when confrontedwith a diversity of stimuli, especially if these involve multiple sensory modalities. We investigated theeffect of the odour of the plantLantana camaraand its dominant volatile compound,b-caryophyllene, onthe prey choice decisions ofEvarcha culicivora,a jumping spider (Salticidae) that frequently visitsL. camaraas a site to mate and to obtain nectar.Evarcha culicivoraexpresses a strong preference forblood-fed femaleAnophelesmosquitoes as prey. We tested juvenile and adultE.culicivorain experimentsinvolving live prey, lures made from dead prey and virtual prey, when presented with no odour, odourfromL. camaraandb-caryophyllene. We found that, in the presence of the plant-related odours,E. culicivora's prey preference was no longer expressed. This effect seems to be a consequence of theplant-related odours reducing the extent to whichE. culicivorarelies on a pre-attack pause and visualfixation routine (‘stationing’) when seeing prey. Stationing may be critical for adequate visual scanning,and thus correct identification of the prey, as we found that the longer the spider was stationed in frontof prey before being subjected to a disruption, the more stronglyE.culicivoraexpressed a preference forblood-fed female mosquitoes. This seems to be an unusual example of a specific modulation of visuallybased prey choice behaviour being mediated by an environmental chemical cue not pertinent to the prey.©2021 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved