Aphis gossypii Glover is one of the major pests of cucumber in Iran. The effects of different concentrations of nitrogen (N1 = 0, N2 = 30, N3 = 60, N4 = 90 and N5 = 120 kg/ha), phosphorus (P1 = 0, P2 = 15 and P3 = 22.5 kg/ha) and silicon (Si1 = 0, Si2 = 100 and Si3 = 200 kg/ha) on life table parameters of apterous morph of A. gossypii were studied. This study was conducted as factorial experiment based on RCD with nine replications in a growth chamber at temperature of 25 ± 3 °C, 60 ± 5%

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... e humidity (RH) and a photoperiod of 16: 8 h (light: dark). The experiments were carried out using clip-cages that were fixed on leaves of cucumber growing in pots. According to the results, total fecundity of A. gossypii significantly was different among treatments and it was the highest on N1P2Si2 (64.33 offspring) and the lowest on N3P2Si1 (22.67 offspring). The lowest and the highest values of R0 were observed on N3P2Si1and N4P2Si2, respectively. The shortest mean generation time (T) was found on N4P1Si3 and the longest was on N5P3Si1. Furthermore, the lowest and the highest values of r were obtained on N5P3Si2 (0.27 day-1) and N5P1Si1 (0.41 day-1). Our results showed that in simultaneous application, the phosphorus had a more impact on life history and performance of cotton aphid.