Effect of Constant Temperature on Development and Reproduction of the Cotton Aphid (Aphis gossypii) (Glover) (Hemiptera: Aphididae) on Gossypium hirsutum in Laboratory Conditions

Temperature-dependent development, survivorship and reproduction of the cotton aphid, Aphis gossypii on Gossypium hirsutum were evaluated at six constant temperatures (10 0 , 15 0 , 20 0 , 25 0 , 30 0 and 35 0 C). The clean statistical breaks between developmental durations of all immature stages of aphids held at 10 0 and 15 0 C indicate that at lower temperatures, all immature aphid stages (1 st to 4 th instars) are affected similarly by temperature changes. In viewing the survivorship curves ( l x ) for aphids held at the six constant temperatures, a general trend is evident. As temperature increased, survivorship progressively fell more precipitously, indicating increasing aphid mortality at a younger age. At 10 0 , 15 0 , 20 0 , 25 0 , 30 0 and 35 0 C, aphid survivorship dropped below 80% at 39, 29, 33, 21, 20, and 14 days of life, respectively. Gross reproductive rate (GRR) an indicator of lifetime fecundity, ranged from 9.8 for aphids held at 10 0 C to 58.9 for aphids held at 30 0 C. A general rise in GRR was observed with rising temperature to 30 0 C. The optimum temperature is closer to 25 0 C. The results of this study agree with previous studies that the optimum aphid development temperature (held constant) in a laboratory study is 25 0 to 30 0 C.