Effects of previously damaged strawberry plants on Tetranychus urticae Koch (Acari: Tetranychidae)
2003 - Volume: 43 Issue: 1-2 pages: 59-65
We report the effect of initial damage on subsequent populations of Tetranychus urticae Koch in two strawberry cultivars. In Selva, the damage levels assayed were 622.50 and 2458.75 mite-days/plant. In Milsei Tudla, they were 1157.80, 2339.15 and 4101.20 mite-days/plant. After the damage, the plants were kept free of mites during 15 days. Excised leaves of Selva and whole plants of Milsei Tudla were infested with 10 females, counting the offspring at different intervals. In Selva, the number of eggs and immatures of T. urticae and the egg-days/female-days ratio were higher in plants exposed to the highest level of damage. This effect was not detected in Milsei Tudla. The stage survival rates and the duration of stages were unaffected by previous damage in both cultivars. The demographic pattern found in Selva suggests that induced susceptibility against T. urticae is due primarily to differences in fecundity.
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