Alterations in foraging behavior of Coccinella septempunctata and Propylea japonica mediated by a novel defended prey affect their predatory potential

Generalist aphidophagous coccinellids have to cope with novel prey aphids in environments that are changing rapidly because of anthropogenic activity. The goldenrod aphid, U roleucon nigrotuberculatum ( O live) ( H emiptera: A phididae), is a noxious prey, which was recently introduced into Japan. It is a major prey for the native Japanese predators C occinella septempunctata bruckii M ulsant and P ropylea japonica ( T hunberg) (both C oleoptera: C occinellidae) in early summer on patches of solidago, S olidago altissima L. ( A steraceae). Prey preference of these coccinellids between this aphid and a native suitable prey aphid, M egoura crassicauda M ordvilko ( H emiptera: A phididae), as well as their foraging behavior were studied for a better understanding of the negative impacts of the noxious novel aphid. C occinella septempunctata initially preferred the novel prey, but later switched to the native prey, M . crassicauda ; P . japonica had no preference for either prey. Feeding time of the first instars of C . septempunctata on U . nigrotuberculatum was significantly longer than that of P . japonica . The foraging bouts of fourth instars of C . septempunctata were significantly longer on U . nigrotuberculatum than on M . crassicauda , whereas only the feeding time of fourth instars of P . japonica on U . nigrotuberculatum was significantly longer than on M . crassicauda . Both coccinellids consumed less of U . nigrotuberculatum than of M . crassicauda . Thus, solidago patches infested by U . nigrotuberculatum may present an ecological trap, especially for C . septempunctata .