Functional response and population parameters of Phytoseiulus persimilis (Acari : Phytoseiidae) Athias-Henriot on Tetranychus urticae (Acari : Tetranychidae) Koch.

The functional response and population parameters of Phytoseiulus persimili s Athias-Henriot, a phytoseiid predator on eggs, larvae and nymphs of Tetra nychus uriticae Koch were investigated. The predation trials were conducted on greenhouse bean leaf discs over a period of 24-h at 28+/-2 degreesC and 60% RH. The functional response was of Type II according to Holling's (195 9) model. The rate of instantaneous discovery (a') was 1.0175 for eggs, 0.9 785 for larvae and 1.1068, for nymphs, while handling time (Th) was 0.00821 , 0.0044 and 0.01498 for the same stages. Other parameter estimates in this study are a net reproduction rate (Ro) of 41.1081, intrinsic growth rate ( r(m)) of 0.4099, finite growth rate (lambda) 1.5068 and generational time ( Tg) 9.0639.