THE FATE OF RADIOPHOSPHORUS INGESTED BY HABROBRACON FEMALES ,

Abstract

These expts. involved nearly 300 wasps. After a single feeding of P32 in honey, the biological half life in Habrobracon is attained between 4 and 5 days. A major channel whereby the isotope is eliminated is shown to be the egg. Comparisons of the radioactivity of laying and non-laying wasps were made and direct evidence of egg radioactivity is presented. Furthermore, excretory studies are included which employ a new technique of rearing in a gelatin capsule, subsequently digested and exposed to GM counting. Radioactivity of eggs reaches a peak the 2d day after feeding; after the 3d day it drops sharply to a relatively low plateau. Variability in the radioactivity from egg to egg may prove to be less each succeeding day. Although it is an important factor in the regulation of total activity, quantitative egg laying has not been found significant in determining P32 distr. A mobile, adjustable situation is indicated. In percentage of total, the abdomen contains almost 90% during the 1st day, about 65% for 4 succeeding days, when the content falls to near 50%. Gamete-incorporated radiophosphorus appears adequate to be pertinent to interpretations of hatchability of eggs laid the 1st 5 days. Subsequently, initial exposure and accrued total dosage may have greater significance.