Nutrition of Glossina morsitans: metabolism of U-14C glucose during pregnancy.

A Glossina morsitans female can synthesize alanine, aspartic acid, cystine, glutamic acid, glycine, proline, and serine, and also lipids, from d-[U-¹⁴C] glucose during pregnancy and utilize these products for nourishment of the growing intra-uterine larva. The third instar larva shortly after formation of the puparium can also synthesize these nutrients from glucose and is thus similar to the adult female fly in this respect. It is possible that some glucose taken up by the larva via the maternal uterine glands is converted to the above nutrients. Although the specific nutritional requirements of the growing larva are largely provided by its female parent, the larva has active synthetic systems for the regulation and maintenance of its inherent metabolic steady state. This is reflected in the synthesis of large amounts of glutamic acid in the larva whereas in the adult the emphasis appears to be on the synthesis of proline.Most of the injected glucose and its synthetic products are utilized to provide energy for biosynthetic activity. Uric acid is the main nitrogenous end product of catabolism of non-essential amino acids. A small proportion of such amino acids and glucose are also excreted.Embryonic development which lasts for about 4 days following ovulation is sustained by nutrients within the egg. Following eclosion, the first instar larva begins to feed upon uterine gland secretions. This instar lasts for about 1 day. Ecdysis to the second instar, which lasts for 1 to 2 days, is associated with a three- to fourfold increase in the rate of nutrient uptake. Most rapid feeding begins when the third instar develops. These results are discussed in terms of larval growth in relation to feeding by the adult female parent.