1. A method is described for rearing a sieve tube sucking aphid, N. circumflexus, for at least 10 generations on a totally synthetic, sterile diet. 2. Without addition of iron, zinc, manganese, copper, and calcium to the diet the reproduction of first generation aphids is greatly reduced. Second generation aphids are sterile. 3. Adding the trace elements individually, concentrations for optimal growth of first generation aphids were determined with: 460 μg Fe, 220 μg Mn, 190 μg Zn, 850 μg Ca, and 100 μg Cu (per 100 ml diet). 4. Addition of iron and zinc to the food increased aphid weights three times and reproduction rates considerably. Lack of both caused total sterility in the third generation. 5. Omission of manganese decreased growth and reproduction of the aphids in the second generation, and caused sterility in the fourth. Zinc acts as a Synergist to manganese. 6. Deprivation of calcium reduced aphid growth more and more from the first to the third generation. The fertility in the second generation was considerably decreased and malformed larvae deposited in the third. Calcium acts as an antagonist to zinc and manganese. 7. A deficiency of copper became apparent in the second generation, causing reduced growth and fertility from this to the fifth generation up to total sterility in the sixth. 8. If all trace metals are included in the diet growth and reproduction of first generation aphids are equal to those on Vicia faba. Both is reduced to 90% in second generation aphids on the diet, but remaining constant in all subsequent generations. 9. The intracellular symbionts of aphids fed on diets lacking trace elements show typical degenerations. Finally, the mycetocytes of second generation aphids are free of symbionts. 10. The microorganisms show a reaction on the addition of trace metals to the aphids food. The degeneration is delayed by gradually adding individual metals. For example, iron and zinc are necessary for maintaining a normal supply of symbionts in second generation aphids. If all elements are added to the diet, no alterations occur. Then, the supply of symbionts of tenth generation aphids on the diet is the same like that of naturally fed aphids. © 1968 Springer-Verlag.
