Preference and performance of Sipha elegans on three wheat cultivars: Response to leaf pubescence

The impact of leaf trichome density of three wheat cultivars (Pishtaz, Ghods and Falat) on preferenceand performance of Sipha elegans was evaluated in the greenhouse condition at 60±5 RH, 20±5 °C and12:12 h (day/night). Trichome density by SEM (Scanning Electron Microscopic) images and microscopicslides was compared. Results showed that Pishtaz cultivar had the maximum density of trichomes,whereas Ghods and Falat cultivars had lower trichomes density, respectively. In choice test, preference ofS. elegans on Pishtaz cultivar was significantly higher than other cultivars in all assessments (P<0.05). Inno choice test, the number of aphids at different hours counting (48 and 72 h) on Pishtaz cultivar wassignificantly more than other cultivars (P=0.01 and P<0.01 after 48 and 72 h, respectively). There was nosignificant difference of intrinsic rate of natural increase (rm) among three wheat cultivars (P>0.05), but itwas the highest on Pishtaz cultivar (0.184 female/female/day). Doubling time (DT), mean generationtime (T) and finite rate of increases (l), also did not show significant difference between the cultivars.However, net reproductive rate (R0) was the highest on Falat cultivar (35.9 female/female/generation) andit was significantly differ to that on the other cultivars. According to these results, S. elegans showed thehighest preference and performance on Phishtaz cultivar, with maximum trichomes density that representsthe susceptibility of this cultivar to the activity of S. elegans than the other cultivars.