Susceptibility of Tetranychus uticae Koch (Acari: Tetranychidae) on seven strawberry cultivars

ABSTRACT: The two-spotted spider mite, Tetranychus urticae Koch is one of the cosmopolitan pests, which attack many agricultural and greenhouse plants. The suitability of seven strawberry cultivars (Marak, Yalova, Aliso, Gaviota, Sequoia, Camarosa and Chandler) for the development, reproduction and preference of T. urticae were investigated. To antixenosis mechanisms of resistance, 400 adult mites were released in the center of seven cultivars. Mites were counted 24 and 48 hours after releasing. Sequoia and Marak could be defined as preferred and Gaviota was the least preferred by the spider mite. Antibiosis test was studied on leaflet of the same cultivars. Life table parameters of T. urticae was studied in the laboratory conditions (27±1?C, 60±5% RH and 16L: 8D photoperiod). Data were analyzed based on the age-stage, two-sex life table theory. Proportion of mite surviving to adult ranged from 48% to 84%. Duration of protonymph and deutonymph stages reared on different cultivars showed a significant difference. Total longevity of mites reared on Chandler (10.58 days) were significantly longer than those reared on other cultivars, whereas female longevity was the same on the seven strawberry cultivars. The life time fecundities of T. urticae on Marak and Sequoia (26.70, 45.43 eggs/female, respectively) were lower than those on other cultivars. Lowest intrinsic rate of increase found in mites reared on Marak and Sequioa. Higher intrinsic rate (0.28 day-1) and fecundity found in mite reared on Chandler, it may be due to the higher nutritional quality and low density of trichome. Marak and Sequoia were least suitable cultivars for T. urticae.