The effect of common bean cultivars on life table parameters of Tetranychus urticae (Acari: Tetranychidae)

Abstract

It is well recognized that the quality of host plants affects the development and survival of herbivorous arthropods. The life table parameters of Tetranychus urticae Koch, on six cultivars of common bean ( Phaseolus vulgaris L.) Khomein, chiti Ks21189, red Akhtar, red Ks31169, white Pak and white G11867 were studied at constant laboratory conditions (27±2oC, 70±5% RH and 16 L:8 D h), during 2009–2011. Results showed that the immature developmental times of males and females were significantly influenced by bean cultivars. Tetranychus urticae laid significantly more eggs per day on red Akhtar cultivar (16.16) compared with the other cultivars. The mean generation time affected by different cultivars and it’s ranged varied from 23.37 to 34.82 days. Percentage the egg hatching of TSSM ranged varied from 88.25% to 94.20%. The highest intrinsic rate of increase ( r m ), was recorded on red Akhtar (0.269±0.031day -1 ) and the lowest value was obtained on white Pak (0.129±0.048day -1 ). In addition, net reproductive rate ( R 0 ) and finite rate of increase ( λ ) of the TSSM had the highest value on red Akhtar (62.38±1.05 female offspring and 1.30±1.02 day -1 , respectively). The lowest values of these parameters were recorded on white Pak as 27.37±1.40 female offspring and 1.13±1.10 day -1 , respectively. Doubling time ( DT ) varied significantly on different cultivars and its shortest and longest values were obtained on red Akhtar and white Pak, respectively. Our findings revealed that white beans (Pak and G11867) were less suitable cultivars, suggesting that they are more resistant to the TSSM than the other cultivars.