INFLUENCE OF TEMPERATURE AND DAYLENGTH ON POPULATION DEVELOPMENT OF APHIS-GOSSYPII ON CUCURBITA-PEPO

The life table parameters of Aphis gossypii Glover were evaluated in t ow sets of experiments on Cucurbita pepo. The first set was conducted at six constant temperatures (5-degrees-C increments from 10-35-degree s-C) with 12 h photophase. The second set of experiments was conducted at 6, 12, and 18 h photophase at 25-degrees-C. Nymphal survivorship w as 100 % at 15, 20, 25 and 30-degrees-C. However, it was 80 and 0 % at 10 and 35-degrees-C, respectively. The optimum temperature for body l ength was 10-degrees-C, and body length decreased with increasing temp erature. A. gossypii attained its optimum growth and reproduction at 2 5-degrees-C. At this temperature, the net reproductive rate (79.7), in trinsic rate of increase (0.496) and finite rate of increase (1.6) wer e largest while generation time (6.6 d) and population doubling time ( 1.4 d) were smallest. Temperatures above and below 25-degrees-C reduce d the net reproductive rate, and the intrinsic and finite rates of inc rease. The intrinsic and finite rates of increase of A. gossypii reare d at 18 h photophase (0.53 and 1.7) were significantly higher than at 12 (0.43 and 1.5) and 6 h daylength (0.49 and 1.6).