Previous exposures to cues from conspecifics and ladybird beetles prime antipredator responses in pea aphids Acyrthosiphon pisum (Hemiptera: Aphididae)

When prey encounter predators, they exhibit antipredator responses to reduce their risk of predation. Delayed responses can be fatal. Because prey can assess the risk of predation using predation-related cues, previous exposures to these cues could affect subsequent antipredator responses. We tested this possibility using the pea aphid Acyrthosiphon pisum Harris (Hemiptera: Aphididae) and its predator the Asian ladybird beetle, Harmonia axyridis Pallas (Coleoptera: Coccinellidae). Aphids disperse from their host plants after sensing predators. We investigated whether previous exposures to cues from conspecifics and ladybird beetles affected the dispersal rates of aphids encountering predators. The cues contained visual, chemical, and vibrational information from aphids and ladybird beetles. Aphids that had previously been exposed to these cues increased dispersal rates and, consequently, suffered less predation than unexposed aphids. To clarify how aphids increased their dispersal rate, we examined their feeding times. Aphids that had been exposed to cues reduced feeding times compared with unexposed conspecifics. Therefore, we further tested whether the predator-induced dispersal of non-feeding aphids was greater than that of feeding conspecifics and found correlated differences. Previous exposures to cues from conspecifics and predators may allow prey to tune their antipredator responses to predation risk prior to further predator encounters.