Demographic Traits of Tetranychus urticae (Acari: Tetranychidae) on Leaf Discs and Whole Leaves

Life tables of two spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae), were studied on leaf discs and whole leaves of the common bean plant, Phaseolus vulgaris L. Data were analyzed based oil the age-stage, two-sex life table theory. Durations of deutonymph stage, total preadult stage,and preoviposition period of mites reared oil whole leaves (1.22, 7.6,and 0.29 d, respectively) were significantly shorter than those reared on leaf discs (1.73, 8.2, and 0.89 d, respectively). The lifetime fecundities were 22.81 and 12.05 offspring on whole leaves and leaf discs, respectively. Although hooked trichomes on the lower surface of the can leaf contribute to adult mortality, spider mites successfully survive and reproduce oil bean plants. The intrinsic rate of increase oil whole leaves (0.235 d(-1)) was higher than that oil leaf discs (0.159 d(-1)). Higher intrinsic rate and fecundity found in mites reared on whole leaves may be due to the higher nutritional quality of whole leaves over leaf discs. We suggest that whole leaves should be used in future studies to better simulate realistic life-history characteristics. The advantages of using age-stage, two-sex life tables over female age-specific life tables are discussed.