TOXICOLOGY OF CUPRIC SALTS IN HONEYBEES .2. FEEDING-BEHAVIOR FOR DIFFERENT ORGANIC SALTS AND COMPARATIVE TOXICOKINETICS OF DIETARY GLUCONATE AND SULFATE

Worker honeybees were fed with 2M sucrose syrups pure or containing a range of added concentrations of various cupric salts. The rate of ing estion of the different syrups decreased in the following order: gluco nate > asparaginate > glutamate > sulfate = glycinate > citrate. Decre asing dose-related responses were observed for aspartate, isoleucinate and sulfate, in pollensupplied or more markedly in pollen-deprivated groups, and for gluconate under pollen deprivation conditions only. Ra tes of ingestion for glycinate, glutamate, asparaginate and lactate we re not improved by mixing an equal part of gluconate with these soluti ons. Glucoheptonate and pyroglutamate showed ingestion rates between a sparaginate and glutamate. The accumulation and release of copper meta l in the whole body of bees was studied for sulfate and gluconate with or without pollen supply. A saturation phenomenon appeared in each ca se, but with higher levels for sulfate, thus limiting the concentratio ns retained. by the bee's body, whatever the concentrations they were fed with. The kinetics of copper release from bees fed with syrups con taining no added copper exhibited a sigmoidal curve, as did the percen tages of copper elimination at various doses of gluconate or sulfate, reaching maxima of 97.5-98.5 %. The corresponding EC50 values decrease d from 6.4 to 5.8 mM and from 7.4 to 5.6 mM respectively when 0.44 to 1.1 mM of each salt was administered indicating low risks of excessive accumulation.