EXCRETION OF CADMIUM AND ZINC DURING MOLTING IN THE GRASSHOPPER OMOCESTUS-VIRIDULUS (ORTHOPTERA)

Nymphs of Omocestus viridulus (Orthoptera) were reared on grass leaves containing known amounts of Cd-109 or Zn-65. After the animals moulte d to adults, contents of these metals were measured in the grasshopper s, in the cast of exuviae and in the feces produced during rearing. Dr y weights of adult bodies and exuviae were lower for Cd-109-treated gr asshoppers than for those given Zn-65. Exuviae accounted for only a mi nor part of the excreted Cd-109 and Zn-65. The Cd-109 was assimilated from food to a much smaller extent than was Zn-65. After 15 d of reari ng, similar to 50% of the ingested Zn-65, but only 10% of the ingested Cd-109, remained in the grasshoppers. Because the amount of Cd-109 in the grasshopper nymphs decreased with time, whereas that of the exuvi ae were constant, content in exuviae constituted a larger portion of t he total content of Cd-109 With increasing time between feeding of Cd- 109 and moulting. For Zn-65 there was no such trend.