Influence of temperature on life-table parameters of Stethorus gilvifrons (Mulsant) (Coleoptera : Coccinellidae) fed on Tetranychus urticae Koch

The influence of temperature on life-table parameters, fecundity and survivorship of the predatory ladybird, Stethorus gilvifrons, fed on Tetranychus urticae was determined at seven constant temperatures of 15 degrees C, 20 degrees C, 25 degrees C, 28 degrees C, 30 degrees C, 35 degrees C and 40 degrees C. No development was observed at 40 degrees C, thus being regarded as the threshold for the development of S. gilvifrons. The results indicate a significant decrease in male and female longevity with increasing temperature from 15 degrees C to 35 degrees C. The longest and shortest longevity were 18.40 and 12.75 days for males and 17.40 and 8.80 days for females, respectively. The intrinsic rate of natural increase (r(m)) and the net reproductive rate (R(0)) of S. gilvifrons linearly increased with increasing temperatures from 15 degrees C to 35 degrees C, while the mean generation time (T) and doubling time (DT) decreased linearly within this temperature range. The highest values of r(m) (0.240 females/female/day) and R(0) (59.27 females/female) and the lowest mean generation time (17.01 days) and DT (2.88 days) were recorded at 35 degrees C. The maximum (185.50 eggs) and minimum (25.50 eggs) measurement of total fecundity was also recorded at 35 degrees C and 15 degrees C, respectively. The results indicate that temperature greatly affected fecundity, survivorship and life-table parameters of S. gilvifrons, and that 35 degrees C is a suitable temperature for population growth of this predator.