REDIRECTION OF METABOLISM IN THE FLESH FLY, SARCOPHAGA-BULLATA, FOLLOWING ENVENOMATION BY THE ECTOPARASITOID NASONIA-VITRIPENNIS AND CORRELATION OF METABOLIC EFFECTS WITH THE DIAPAUSE STATUS OF THE HOST

The rate the O-2 consumption in nondiapausing, pharate adults of sarco phaga bullata steadily increased as development progressed toward adul t eclosion, and this elevation was accompanied by increases in the tot al body content of pyruvate and oxaloacetate and decreases in carbohyd rate (trehalose and glycogen), lipid and protein. In contrast, when no ndiapausing pharate adults were envenomated by the ectoparasitoid Naso nia vitripennis, the rate of O-2 consumption dropped sharply and the t otal body content of oxaloacetate, trehalose and glycogen steadily dec lined. Hemolymph amino acid concentrations, most notably alanine, incr eased following envenomation, but this did not appear to be the result of increased protein hydrolysis or pyruvate metabolism. Pyruvate leve ls initially increased following envenomation but declined rapidly 3-4 days later. The decline of this keto acid occurred concurrently with an increase in total body lipid, suggesting an increase in the rate of host lipogenesis. In diapausing hosts, the rate of O-2 consumption wa s 1/10-1/15 of the lowest rate observed in nondiapausing hosts, total body protein and lipid levels were much higher, pyruvate content was l ower, and oxaloacetate was not detectable. Envenomation did not alter the rate of O-2 consumption or levels of trehalose, glycogen, lipid, a lanine or protein. Pyruvate briefly increased, but the onset and durat ion of this elevation did not coincide with the changes observed in ph arate adults that were envenomated. The failure of diapausing hosts to respond to envenomation by redirecting metabolism may account for the lower production of adult parasitoids on such hosts.