Performance of Tetranychus urticae (Acari: Tetranychidae) on six cotton varieties with varying degree of leaf pubescence

Abstract

In this study, we investigated the effect of leaf hairiness, based on non-glandular trichome density, of six cotton varieties (Gloria, Lima, Carla, DP-396, Edessa and ST-468) on the development, reproduction and population parameters of Tetranychus urticae (Acari: Tetranychidae) under controlled conditions. According to trichome densities (mean number/cm2) on the abaxial surface of cotton leaves: Edessa (583.8) and ST-468 (569.9) were grouped as high density; DP-396 (394.9) and Carla (367.5), medium density; Lima (20.4) and Gloria (13.3), low density. As a result, total development periods of T. urticae in Gloria, Lima, Carla, DP-396, Edessa and ST-468 varieties were 9.7, 9.8, 10.6, 10.6, 11.9 and 11.8 days, respectively. The developmental periods of immature stages and total preadults increased significantly with increasing leaf trichome density. The longest oviposition period of T. urticae was detected in Gloria (27.5 days) and Lima (25.1 days) and the shortest was in Edessa (16.4 days) and ST-468 (17.4 days). The highest total fecundity was determined in Gloria (135.6 eggs) and Lima (131.4 eggs) varieties. The highest intrinsic rate of increase (r), finite rate of increase (l) and net reproductive rate (R0) were obtained in Gloria, Lima, Carla and DP-396, the lowest in Edessa and ST-468 varieties. The longest mean generation time (T) was detected in Edessa (19.0 days) and ST-468 (18.6 days). The result of this study showed that cotton varieties with high trichome density negatively affected the development, reproduction and population parameters of T. urticae.