Labeling Plants and Their Insect Fauna with Rubidium

Abstract

Single applications of aqueous sprays of rubidium chloride (RbCl) were made at rates of 0.625–10 kg/ha to cotton, grain sorghum, and hyacinth bean, Dolichos lab-lab L., to label the plants and insects on them with elevated levels of Rb. However, at all rates tested there was overlapping of the concentration of Rb in insects collected from treated plants with the Rb content of those from untreated plants. Some entomophagous insect species were labeled with Rb, indicating the Rb moved through the food chain from producers through primary to secondary consumers.