Population parameters of Sitophilus granarius (L.) were measured under various conditions of temperature and relative humidity. The range of five examined temperatures ( 15 to 35°C) had a remarkably stronger effect on all examined parameters than applied range of two relative humidities (75%; 85 or 95%). The highest intrinsic rate of natural increase (rm) and the highest finite rate of increase (lambda) were recorded when temperatures of 25 and 30'C were used. The generation time (T) ranged from approximately 10 weeks at 30"C and 75 or 85% RH to approximately 22 weeks when l 5°C was used. At 35°C there were no survivors of any immature stages of S. granarius regardless of relative humidity, so population parameters could not be counted. A brief narrative is presented on the potential of these environmental variables for control applications.

Bionomy of spruce spider mite (SSM) (Oligonychus ununguis Jacobi) on five species/cultivars of spruce and two species of cypress was studied under laboratory conditions during rwo consecutive growing seasons. The study showed influence of host-plant food on development time, fecundity and longevity of SSM. The comparison of intrinsic rate of natural increase (r,J indicates the highest reproduction potential of SSM on Picea pungens (0.18), P. abies 'Nidiformis' (0.17), and P. glauca 'Conica' (0.14). SSM had much lowest rm on P. omorica (O.OS) and P abies 'Virgata' (O.Ol). The reproductive potential of SSM on rested species of cypresses was similar: 0.12 and 0.10 on Chamaecyparis lawsoniana 'Golden Wonder" and C. pisifera 'Nana Aureovariegata', respectively. The results obtained clearly indicate that the population parameters can be a proper indicator ofrelative susceptibility/resistance of commercially available species/cultivars of spruce and cypress plants to SSM.