the leaf nitrogen content is generally accepted as an indicator of food quality and as a factor affecting host selection by phytophagous insects. the alate pea aphids (acyrthosiphon pisum harris, aphididae) were given a choice among non-nodulated pea plants (pisum sativum l.) supplied with one of four nitrate-n levels (0, 3, 15 and 30 mm). when whole plants were exposed to aphids for 7 days, th...
