Abstract
The reproductivity of a fenpropathrin-resistant strain (FS-strain) of Tetranychus urticae (KOCH) was compared with that of a susceptible strain of the same origin (INM-strain) at temperatures of 20°C, 25°C and 30°C. The number of eggs produced by the FS-strain was lower than the number produced the INM-strain, especially at 30°C. There was no significant difference for hatchability of eggs, total development time and survival rate of immature stages and adults between strains. The intrinsic rate of natural increase (rm) was lower in the FS-strain than in the INM-strain at each temperature. These results suggest a lower fitness value for the FS-strain than for the original INM-strain.
