J Razmijou - Department of Plant Protection, Faculty of Agriculture and Natural Resources, University of Mohaghegh Ardabili, Ardabil, Iran
L Mottaghinia - Department of Plant Protection, Faculty of Agriculture and Natural Resources, University of Mohaghegh Ardabili, Ardabil, Iran
N Miraei - Department of Plant Protection, Faculty of Agriculture and Natural Resources, University of Mohaghegh Ardabili, Ardabil, Iran

The melon aphid, Aphis gossypii Glover (Hem., Aphididae) is a cosmopolitan and polyphagous species, which is known as an important pest of cucumber. Different cultivars of a plant can influence the demographic parameters of pests. In this research, the population growth parameters of the melon aphid were studied on nine different cucumber cultivars including Isfahan, Bahman, Bonanza, Beit alpha, Talsia, Davus, Sakata, Suprina, and Yalda. The experiments were carried out in Petri dishes at 25 ± 2 °C, 65 ± 5% RH and 16L : 8D in a growth chamber. Standard errors of the population growth parameters were calculated by the Jackknife method and the data were analyzed by SPSS software. Various cucumber cultivars significantly affected the population growth parameters of A. gossypii. The net reproductive rate (R0) of the aphid varied from 47.16 to 109.78 female / female / generation which was lowest on Bonanza and highest on Sakata cultivar. The intrinsic rate of natural increase (rm) of the melon aphid were ranged from 0.4359 to 0.5320 day-1 on different cultivars. It was lowest on Bonanza and highest on Sakata, Talsia and Beit alpha cultivars. The lowest and highest values of finite rate of increase (λ) were obtained on Bonanza and Sakata cultivars, respectively. Mean generation time (T) of the aphid were varied from 8.07 to 8.97 d. The doubling time (DT) was highest on Bonanza and lowest on Sakata cultivar. The results showed that among the investigated cultivars, Bonanza was the least suitable cultivar for A. gossypii.

Cucumber; demography; intrinsic rate of natural increase; melon aphid; resistant cultivar