Mothers forewarn offspring about predators: a transgenerational maternal effect on behavior.

Predation risk has long been known to exert a strong influence on behavior, but no study to date has determined whether predators influence offspring antipredator behavior via maternal effects. Here, we provide a unique example of a transgenerational maternal effect in antipredator behavior that takes the form of a "warning" about predators that female fall field crickets Gryllus pennsylvanicus transmit to their offspring. Specifically, the offspring of gravid crickets exposed to a wolf spider Hogna helluo exhibit greater antipredator immobility in response to Hogna chemical cues than do offspring of nonexposed females. These "forewarned" crickets exhibit greater survival in the presence of Hogna than do those not forewarned. Accordingly, gravid crickets from areas with significant Hogna populations produce offspring that are more responsive to Hogna cues than do those from nearby Hogna-free areas. Such transgenerational maternal effects may be more common than currently realized.