RUBIDIUM AS A MARKER FOR MEXICAN BEAN BEETLES, EPILACHNA-VARIVESTIS (COLEOPTERA-COCCINELLIDAE)

Mexican bean beetles, E. varivestis Mulsant, were marked with Rb by allowing larvae and adults to feed on foliage of bean plants treated with a rubidium chloride solution. Detection of Rb was effected by atomic absorption spectroscopy. Adults which had fed for 4 days on rubidium-chloride-treated plants then transferred to untreated plants contained elevated levels of Rb up to 34 days. The presence of Rb was not detectable in the progeny of treated beetles at levels significantly different from controls. Consumption of rubidium-chloride-treated foliage produced no observable detrimental effects on the beetles. The technique allowed them to acquire a relatively permanent label through their normal feeding activity.