Effects of l-canavanine on arginine catabolism in manduca sexta (sphingidae: lepidoptera)

Abstract

1. 1. Hemolymph ornithine concentrations in tobacco horn worm larvae fed a 2.5 mM l -canavanine plus 25 mM l -arginine-supplemented artificial diet (CAAM) were higher than those in larvae fed diets supplemented with 2.5 mM canavanine (CAV), 25 mM arginine (ARG), or controls (CON). 2. 2. Ornithine concentrations in CAV-treated larvae were significantly greater than the control or ARG treatment, but less than the CAAM treatment during the latter part of the wandering larval stage and during the pharate pupal stage. 3. 3. Urea concentrations were greater during the active feeding stage with the CAAM- and ARG-treated larvae having significantly higher levels than control or CAV-treated larvae. 4. 4. Urea concentrations in all treatments never exceeded 36.5% of the ornithine concentration. 5. 5. Canavanine concentrations were higher in CAV-treated larvae than in CAAM-treated larvae. 6. 6. During active feeding, arginine concentrations for all treatments were similar, but were lower in CAV- and CAAM-treated larvae during the pharate pupal stage.