Differences between species and instars of Phratora leaf beetles (Coleoptera, Chrysomelidae) in the probability of being preyed on

Abstract

The defence against predators of two closely related leaf beetle species was compared. Phratora vitellinae (Linnaeus) is known to use plant precursors in producing defensive compounds but P. polaris (Sparre Schneider) obviously synthesizes its defensive compounds from the first on its own, which is known to be true for all the other Phratora species studied except P. vitellinae. In predation experiments P. vitellinae was significantly less eaten by spiders than P. polaris. First instar larvae of P. polaris were more susceptible to spiders than older larvae. This may be explained by instar specific defensive behaviour of the larvae.