P. Grostal et M. Dicke, Direct and indirect cues of predation risk influence behavior and reproduction of prey: a case for acarine interactions, BEH ECOLOGY, 10(4), 1999, pp. 422-427
Little is known about the flow of chemical information from higher to lower
levels within the animal food chain. However this information may determin
e the behavior and distribution of many animals (e.g., that of potential pr
ey) when exposed to direct and indirect cues of predation risk. We used her
bivorous spider mites, Tetranychus urticae Koch (Tetranychidae) as a model
to examine the foraging and oviposition decisions that prey make when expos
ed to these cues. We conducted laboratory tests to determine if the previou
s presence of predators (direct cues) on leaf discs or the presence of inju
red conspecifics (indirect cues) alters the distribution of adults and eggs
of T. urticae. When given a choice, after 24 h, fewer adults and eggs were
found on leaf discs that had previously contained specialist spider mite p
redators, Phytoseiulus persimilis Athias-Henriot (Phytoseiidae), than on di
scs unexposed to predators. Also, more T. urticae emigrated from predator-e
xposed discs than from unexposed discs or from those that had previously co
ntained nonpredatory mites (Tyrophagus putrescentiae, Acaridae). Finally, f
ewer T. urticae foraged and laid eggs on predator-exposed discs or on those
with artificially damaged conspecifics (eggs or dead adults) than on discs
with intact conspecifics. Tetranychus urticae probably recognizes infochem
icals (kairomones) from its predators or cues from injured spider mites and
consequently avoids feeding or ovipositing in areas exposed to these cues.
Recognition and avoidance of kairomones from specialist predators by this
prey are likely to be hereditary, but avoidance of injured conspecifics may
be an adaptation to avoid predators that are not inherently recognized. We
discuss the behavioral and ecological implications of our findings.