Demographic Comparison of the Tetranychus urticae Koch. (Acari: Tetranychidae) Reared on Different Cultivars of Strawberry.

The twospotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae), is an important pest of strawberry (Fragaria × ananassa Duch.) grown in greenhouses and outdoors. In this study, we evaluated the resistance status of five common strawberry cultivars ('Aromas', 'Kurdistan', 'Missionary', 'Paros', and 'Queen Elisa') under laboratory conditions. The developmental times of the preadult and adult stages, total longevity, reproduction, and life table parameters were analyzed according to the age-stage, two-sex life table theory, which provides the most comprehensive description on the survival, stage differentiation, and reproduction of a population. Preadult development was the shortest on Kurdistan and longest on Aromas (17.70 d vs. 21.00 d). The greatest number of oviposition days occurred on Missionary (28.65 d), whereas the fewest were on Queen Elisa (21.58 d). The intrinsic rate of natural increase (r) and finite rate of increase (λ) varied among the cultivars. The highest values were found on Kurdistan (r = 0.1436d-1, λ=1.1544d-1), while the lowest values were on the Aromas cultivar (r = 0.1081d-1, λ=1.1141d-1). The longest mean generation time (T) of T. urticae occurred on Aromas. Based on the results of the present study, the cultivar Aromas was considered the most resistant to T. urticae and least favored strawberry cultivar for the development and reproduction of the mite. Demographic data of twospotted spider mite on these five strawberry cultivars can be used to improve our understanding of the population dynamics of the pest and thereby develop effective pest management strategies against T. urticae in both integrated and organic strawberry production.