Abstract
The effects of temperature on the life history traits of Rhopalosiphum maidis (Fitch) were determined at 6, 10, 15, 20, 25, 30, and 35±1°C on corn leaves, Zea mays (L.). At 35°C, only a few nymphs survived and completed development, but all failed to reproduce. Total immature stages from birth to adult decreased as temperature increased from 51.7 d at 6°C to 5.2 d at 30°C, but became 8.0 d at 35°C. Overall immature development required 119.05 degree-days above 4.44°C. Adult longevity was as high as 26.7 d at 15°C, but significantly declined at 30 and 35°C. The average adult fecundity was as high as 45 offspring at 15 and 20°C, but dropped to 1.8 at 6°C and 8.6 at 30°C. In general, as temperatures increased, age-specific survivorship (lx) declined more quickly, but age-specific fecundity (mx) peaked earlier. At 25°C, the age-specific net maternity (vx=lxmx) was the highest in the early reproductive period, resulting in the highest intrinsic rates of increase (rm=0.329). At 20–30°C, the values of rm were significantly higher than those at lower temperatures. The results indicate that corn leaf aphids probably are better adapted in population growth to a wider range of high temperatures in warm regions.
