Little has been done to compare the relative importance of various mechanis
ms through which prey assess the potential risk from natural enemies. We us
ed predator-naive spider mites (Tetranychus urticae, Tetranychidae) to (1)
compare the responses of prey to chemical cues from enemy and non-enemy spe
cies and (2) investigate the source of these cues. In the laboratory, we ob
served the distribution of T. urticae in response to cues from nine mite sp
ecies, including (1) predators of spider mites. (2) predators/parasites of
other animals, and (3) fungivores/pollen-feeders. When given a choice over
24 h, spider mites foraged and oviposited in fewer numbers on leaf discs th
at were previously exposed to predatory or parasitic mites (including speci
es incapable of attacking spider mites) than on clean leaf discs (unexposed
to mites). Interestingly, previous exposure of leaf arenas to fungivores a
nd pollen-feeders had no significant effect on spider mite distribution. We
then observed the response of T. urticae to cues from two species of preda
tor that had been reared on a diet of either spider mites or pollen, ir: ur
ticae showed stronger avoidance of leaf discs that were previously exposed
to spider-mite-fed predators than of discs exposed to pollen-fed predators.
Nevertheless, for one predator species (Amblyseius andersoni), T. urticae
still preferred to forage and oviposit on clean (unexposed) discs than on d
iscs exposed to pollen-fed predators. Protein-derived metabolic wastes of p
redatory or parasitic mites may provide a general cue about potential preda
tion risk for T. urticae. However, T. urticae also avoided areas exposed to
pollen-fed predators, suggesting there may be other sources of enemy recog
nition by the spider mites. We discuss the ecological and evolutionary mech
anisms that may influence the scope of information through which animals as
sess predation risk.