SOME MINERAL REQUIREMENTS OF THE PEA APHID,ACYRTHOSIPHON PISUM(HOMOPTERA: APHIDIDAE)

Abstract Performance of the pea aphid, Acyrthosiphon pisum (Harris), on a holidic diet containing different metal ions was studied by individually incorporating into the diet a salt of the metal ion to be tested. The performance of the pea aphid was markedly improved when the diet contained iron; the first-generation adults reproduced, and the second-generation nymphs moulted twice or thrice, but did not reach the adult stage. Molybdenum, boron, and copper, at certain concentrations, induced the production of some live nymphs, but manganese, zinc, calcium, and cobalt did not. However, the presence of zinc, cobalt and calcium, at most of the concentrations used, slightly improved growth and reduced mortality. Furthermore, the presence of calcium appeared essential for development to the adult stage. Tolerance to all these metals was fairly high, but sodium molybdate at a concentration of 50.0 mg, and sodium borate at concentrations of 40–100 mg/100 ml of diet, appeared to reach toxic levels.Iron was found to be essential for reproduction and a range of 53–211 μg of elemental iron per 100 ml of diet appeared to be optimum. It is suggested that a synergistic effect between at least some of these metals is required for continuous reproduction of the pea aphid.