A Simple Autoradiographic Method for distinguishing Insects labelled with Phosphorus-32 and Sulphur-35

Abstract

THE use of radioactive tracers for labelling insects is finding many applications in field studies on dispersion and survival. In particular, the introduction of autoradiography for detecting tagged insects¹ has presented entomologists working in remote areas with a simple and practical tool. In studying the longevity of marked populations, however, this technique suffers from the disadvantage that it records only the presence or absence of radioactivity in recaptured insects. No variation in the marking of different releases is possible, and a second release can only be made when all the survivors of the first have disappeared. When the numbers released depend upon the scale of laboratory rearing, as in the case of insects such as Anopheles gambiae, this may appreciably retard the accumulation of results. To surmount this difficulty the following method, that enables the separation by autoradiography of insects labelled with one of two or possibly more different isotopes, has been devised.