Metabolism of carbon-14-labeled hempa by adult boll weevils.

When uniformly carbon-14-labeled hempa, alone or in combination with busulfan, is ingested by the adult boll weevil (Anthonomus grandis Boheman) during a six-day feeding period, hempa is metabolized rapidly and excreted with its decomposition products. The primary metabolic pathway involves the sequentialN-demethylation of hempa to the inactive penta-, tetra-, and trimethyl derivatives. Radiocarbon liberated during metabolism is expired as14CO2 or is incorporated into natural constituents. Of the radioactive products that are present in adult boll weevils immediately upon transfer from the hempa-containing diet, only 0.6 µg each is in the form of hempa; after 24 hours of feeding on untreated diet, this is reduced to 0.06 µg. In view of the known low acute- and chronic toxicity of hempa to mammals and its low mutagenicity in mammalian systems, it is concluded that the proposed release of 100 chemosterilized weevils per acre would produce only negligible potential environmental contamination and that possible risks could be further reduced by releasing the insects 24 hours or more after treatment.