An alternate route to insect pharmacophagy: The loose receptor hypothesis

The phagostimulatory response of some diabroticite cucumber beetles toward triterpene cucurbitacins is used as a model in support of an alternative hy pothesis explaining the evolution of pharmacophagous feeding behavior in in sects. Whereas the use of noxious compounds from nonhost sources for purpos es other than nutrition or host-plant recognition (pharmacophagy) has histo rically been explained in terms of the ancestral host hypothesis, we sugges t that the less than perfect specificity of the binding properties of some peripheral receptors provides an opportunity for novel compounds sharing th e configuration and polarity of target molecules to elicit a feeding respon se by coincidence rather than adaptive design.