METABOLISM OF L-CANAVANINE AND L-CANALINE IN THE TOBACCO BUDWORM, HELIOTHIS-VIRESCENS [NOCTUIDAE]

The metabolism of L-canavanine and L-canaline were investigated in larvae of the tobacco budworm, Heliothis virescens [Noctuidae]. H. virescens larvae were treated with L-[1,2,3,4-C-14]canavanine or L-[U-C-14]canaline with sufficient cold carrier to provide 5 mg g-1 canavanine or a molar equivalent of canaline (3.81 mg g-1). The preponderant catabolite in both canavanine- and canaline-treated larvae was [C-14]homoserine. Other minor metabolites derived from canavanine included [C-14]aspartate/asparagine, [C-14]glutamate/glutamine, [C-14]2-aminobutyrate, [C-14]ornithine, [C-14]proline, and [C-14]isoleucine. Canaline yielded [C-14]glutamate/glutamine, [C-14]aspartate/asparagine, and [C-14]-2-aminobutyrate. Our current studies support the belief that this destructive insect tolerates L-canavanine and L-canaline because of its ability to reductively cleave these potentially insecticidal natural products to L-homoserine and guanidine or ammonia, respectively.