Abstract
Two mealybug species, Planococcus kraunhiae and Pseudococcus comstocki, were reared on germinated broad bean seeds to determine the developmental thresholds and thermal constants in each developmental stage and preovipositional period at six temperatures. Since few Pl. kraunhiae and Ps. comstocki individuals developed into adults at 30°C and 32°C, respectively, their upper temperature limit is around 30°C. The lower developmental threshold temperature (T0) and thermal constant (K) for the entire developmental period were 12.2°C and 331 degree-days (DD) for Pl. kraunhiae, and 10.8°C and 346 DD for Ps. comstocki. T0 in the preovipositional period were 8.1°C and 225 DD for Pl. kraunhiae, and 10.7°C and 163 DD for Ps. comstocki. Fecundity was highest at 24°C in both species. Pl. kraunhiae laid an average of 526 eggs, and Ps. comstocki 498 eggs. The intrinsic rates of the natural increase in Pl. kraunhiae and Ps. comstocki were 0.117 at 24°C and 0.151 at 28°C, respectively.
