Published online by Cambridge University Press: 31 May 2012
Metopolophium dirhodum (Walker), a grain aphid, contained 25.58% dry matter, of which 31.65% was fat, 2.58% sugar, and 39.44% protein. Foliage of the host for M. dirhodum, oats (Avena sativa L.), contained one-third the amount of dry matter, less than one-third as much fat, slightly less sugar, and about three-fifths the amount of protein as M. dirhodum. Phosphorus content was the same in M. dirhodum and its host, whereas oat foliage contained five times as much potassium, and twice as much calcium and magnesium as M. dirhodum. The limiting amino acid in both grain aphid and oat foliage was methionine. Protein scores, which are estimates of protein quality, were slightly lower for oat foliage than for M. dirhodum but both are valuable sources of food for predatory insects and other animals.