Influence of temperature on bionomics of cotton aphid, Aphis gossypii, on cotton

Life table parameters of Aphis gossypii Glover (Homoptera: Aphididae) on Go ssypium hirsutum L. were determined at six temperatures (10, 15, 20, 25, 30 , and 35 +/- 0.5 degrees C) in the laboratory. Relationships of life table parameters with temperature were described with mathematical equations. Dev elopment was fastest at 30 OC, with a pre-larviposition period of 4.6 d. Su rvival to adult was greatest at 25 degrees C (81%). Fecundity was highest a t 95 degrees C, with a total fecundity of 28.3 nymphs per female and a mean reproductive rate of 3.1 nymphs per female per day. Threshold temperatures for development in the first through fourth instar and the adult were 8.2, 8.0, 7.2, 6.2 and 7.9 degrees C, respectively. The durations of these stag es, expressed as temperature sums above these thresholds, were 24.2, 23.7, 23.0, 25.5 and 168.8 degree-days (D degrees), respectively. A. gossypii ach ieved its maximum net reproductive number (24.4 nymphs per female) and grea test intrinsic rate of increase (0.386 d(-1)) at 25 degrees C. The high rel ative rate of population increase at 25 degrees C results in a daily popula tion increase of 47% and a doubling time of only 1.8 d, illustrating the tr emendous growth capacity of A. gossypii populations under favourable condit ions. Compared to literature sources, our sourer of A. gossypii, fed on cot ton, showed a comparatively great heat tolerance.