The ingestion of nitrogen and solid matter from Vicia faba by Aphis fabae Scop

SUMMARY Aphis fabae were reared on two varieties of field bean (Vicia faba) on which they differ in fecundity, and the total amounts of solids and nitrogen ingested and assimilated during larval life and during the reproductive and early post-reproductive life were estimated. Larvae ingested 0·7?0·8mg. solids containing 0·02?0·03mg. nitrogen in 7 days of larval life; they ingested and excreted more solids and nitrogen from one variety. Adult virginoparae ingested 4·4?4·9mg. solids containing 0·08?0·09mg. nitrogen during the reproductive life of 3 weeks; they ingested almost equal amounts of solids from each variety and, like the larvae, assimilated about 20%; their dry weights increased slowly during reproductive life and rapidly during early post-reproductive life. Adults assimilated 70% and larvae 50% of the nitrogen ingested and, although larvae assimilated and excreted significantly more nitrogen on one variety, the adults assimilated more nitrogen on the other variety, on which they produced significantly more larvae. The nitrogen content of the sap of both varieties seems more than adequate for the aphids to grow and reproduce and did not determine fecundity.