Marking of Native Phytophagous Insects with Rubidium: a Proposed Technique1

Rubidium applied foliarly to host plants of phytophagous insects functions as a marker that is acquired during feeding and is readily detectable by atomic absorption spectroscopy. This marker has the advantage that it can be incorporated into the insects normal habitat with minimal affect on the environment. Native insects then acquire the mark through normal feeding activity, and are thus marked in a manner that does not adversely affect either their biology or their behavior. Rubidium, as an element, is unique in its potential for this approach to marking because of its low biological toxicity and low concentration in native flora and fauna. Both plants and insects tolerate enrichment of rubidium for marking purposes.