Environmental factors affecting the life-tables of Tetranychus urticae (Acari : Tetranychidae). III : Host-plant nutrition

First, the literature of the last two decades on nutritional effects of host plants on spider mites is briefly reviewed. Second, experiments are described that subjected micro-propagated apple trees to four different levels of each macronutrient N, P and K. Spider mites (Tetranychus urticae Koch) feeding on leaf disks of these plants were checked for their developmental time, egg production and longevity. Plant analysis revealed that the concentration of N, P and K corresponded to the respective treatments. From these mite data, life-tables were constructed and statistically analyzed by the Jackknife technique. The life-table analysis showed a gradual decline in the intrinsic rate of natural increase (r sub(m)) with N and P deficiency.