Effects of leaf properties of some cotton varieties on the biology, reproduction of Tetranychus urticae (Acari: Tetranychidae) and performance of predatory mite, Phytoseiulus persimilis (Acari: Phytoseiidae)

Sülek N. Aydın Adnan Menderes University, Graduate School of Natural and Applied Sciences, Plant Protection Program, Master Thesis, Aydın, 2021. Objective: In this study, the effect of leaf characteristics of some cotton varieties (Gloria, Lima, Carla, DP-396, Edessa and ST-468) on the biology and reproduction of Tetranychus urticae (Acari: Tetranychidae) and the performance of the predatory mite Phytoseiulus persimilis (Acari: Phytoseidae) were investigated. Material and Methods: The study was carried out on different cotton varieties in Petri dishes at 25 ± 1 oC temperature, 65 ± 5% relative humidity and 16 hours lighting in a climate chamber. Results: Total development periods of T. urticae on Gloria, Lima, Carla, DP-396, Edessa and ST-468 varieties were 9.70, 9.84, 10.57, 10.64, 11.91 and 11.80 days, respectively. The developmental periods of immature stages and total preadults increased significantly with increasing leaf hairiness. The longest oviposition period of T. urticae was detected in low hairy varieties, Gloria (27.5 days) and Lima (25.1 days) and the shortest was in high hairy varieties, 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 () and net reproductive rate (R0) were obtained in low hairy (Gloria and Lima) and medium hairy (Carla, DP 396), the lowest in high hairy (Edessa, ST-468) cotton varieties. The longest mean generation time (T) was detected in high hairy varieties, Edessa (19.03 days) and ST-468 (18.61 days). The predation rate of P. persimilis feeding on T. urticae eggs was not statistically different among the cotton varieties depending on different prey densities. The predation rate of P. persimilis, however, was numerically highest in low hairy varieties Gloria and Lima when T. urticae protonymphs were given as prey. In addition, the highest attack rate () of the predator to eggs and protonymphs was detected in Gloria (low hairy variety). Conclusion: The result of this study showed that leaf hairiness in cotton varieties affected the development, reproduction and population parameters of T. urticae and the predation rate of P. persimilis (for protonymphs). Keywords: Cotton, morphological structure, hairiness, Tetranychus urticae, Phytoseiulus persimilis, life history parameters, consumption rate