The Effect of Nitrogen Fertilization on Biology and Intrinsic Rate of Increase of Schizaphis graminum R. (Hom.: Aphididae)

The amount of nitrogen fertilizer is an effective factor on the growth، development as well as reproduction of phytophagous insects. To investigate the effect of nitrogen fertilization on green aphid، Schizaphis graminum، wheat considering as a significant host for aphid was treated with four nitrogen levels. Nitrogen fertilization treatments included zero (check) 50، 100، and 150% of recommended levels. Rearing containers were placed into environmental chamber (25±1ºC، 70±10% RH، and 16:8 L: D photoperiod). The results showed that increase in nitrogen fertilization resulted in increase in the percentage of soluble nitrogen concentration in plants (%). The aphids feeding on plants receiving higher nitrogen fertilizer (150%) had longer reproduction period، maturity period as well as greater fecundity and longer longevity، although nitrogen fertilization had no effect pre-reproduction period and post-reprodution period. Intrinsic rate of increase of aphid was calculated on various treatments using Wyatt and White method. The intrinsic rate of increase in treatments of 0، 50، 100، 150% were determined as 0. 246، 0. 266، 0. 263، and 0. 267 (female/female/day)، respectively. The results demonstrated that green aphids feeding on fertilized plants showed to have greater reproduction abilities of aphids comparing check treatment (%).