The Nitrogen Content of Different Varieties of Peas as a Factor Affecting Infestations byMacrosiphum pisi(Kltb.) (Homoptera: Aphididae). A Preliminary Report

The influence of varietal differences in plants on infestation by aphids has received considerable attention in control studies. Painter (14), in 1941, concluded that the composition of the available food in the host plant plays possibly the most important role in determining the relative resistance to aphid attacks. In biological studies onAphis rumicisL., Davidson (8) found that factors that influence the physiological activity of the plant affect also the progress of aphid infestation. The same author (6) also pointed out that aphids exhibit a wide range of fecundity on different hosts. “The sap of certain varieties of beans”, writes Davidson, “appears to have a direct inhibiting effect upon the reproductive capacity of the aphids, whereas that of other varieties seems to have the opposite effect.”