Defensive adaptations of eggs and adults of Gastrophysa cyanea (Coleoptera: Chrysomeliade)

Egg clusters and adults of Gastrophysa cyanea are conspicuous and, like their larvae, are chemically protected. The eggs owe their bright yellow color primarily to beta -carotene and, in addition, contain substantial quantities of oleic acid. At natural concentrations oleic acid effectively deters many species of ants from feeding. The use of fatty acids as deterrents against ants is discussed as a possible widespread phenomenon among insects. During defensive confrontations, adults of G. cyanea exhibit avoidance behavior and may also feign death. In addition, the adults may autohemmorhage or secrete a fluid from elytral or pronotal pores in response to traumatic stimuli. The secretions are effective against ants and contain a mixture of hydrocarbons as well as terpenoid components. The pattern of ontogenetic modification in the defensive chemical repertoire of G. cyanea is discussed.