Rate of Increase of Populations of Cabbage, Green Peach, and Turnip Aphids1 at Constant Temperatures

The maximum finite rate of increase for apterous populations of the cabbage aphid, Brevicoryne brassicae (L.) was 1.14 times per day at 20°C; for the green peach aphid, Myzus persicae (Sulzer), 1.32 times at 25°C; and for the turnip aphid, Hyadaphis pseudobrassicae (Davis), 1.45 times per day at 25°C. The cabbage aphid had the smallest rate of increase at all temperatures, the green peach aphid the greatest rate between 5° and 15 °C, and the turnip aphid the greatest rate between 20° and 30°C. No aphids reproduced at 35°C, only the population of turnip aphids increased at 30°C, and only the population of the green peach aphids increased at 5°C. Other populations decreased at 5° and 30°C. The components of the rate of increase (nymphal development, age-specific survival and fecundity, length of generation, and net reproductive rate) were determined for each aphid at each temperature. Their effect on the rate of increase was examined, as was the age at which 95% of the contribution to the next generation was made. The proportion of each stage in a population with a stable age distribution was also examined. Equations for predicting the rate of increase, and models comparing the relative growth of populations of the three species with time are presented.