Maternal exposure to predation risk increases winged morph and antipredator dispersal of the pea aphid, Acyrthosiphon pisum (Hemiptera: Aphididae)

Prey mothers at risk of predation sometimes change the morphology and/or antipredator behaviour of their offspring to reduce predation risk. When maternal exposure to predation risk changes the morphology of some offspring, it is unclear whether and how the other offspring, which have normal morphology, exhibit antipredator behaviour. We aimed to clarify these behaviours using pea aphids, Acyrthosiphon pisum Harris (Hemiptera: Aphididae), and aphidophagous Asian ladybird beetles, Harmonia axyridis Pallas (Coleoptera: Coccinellidae), which induce aphids to release the alarm pheromone (E)-beta-farnesene (EBF) and to exhibit antipredator responses. Pea aphids exposed to EBF reduced reproduction through changes in the number of wingless offspring, producing more winged offspring than unexposed conspecifics. Wingless aphids whose mothers had been exposed to EBF showed higher dispersal from host plants with predators than the offspring of unexposed mothers. These results suggest that pea aphids at risk of predation increase their offspring survival by increasing the number of winged offspring and antipredator dispersal of wingless offspring.