Effect of temperature on the biology of Acyrthosiphon gossypii Mordvilko (Homoptera: Aphididae) on cotton

Acyrthosiphon gossypii is a widespread, major pest of cotton in central Asia. Effects of specific temperatures on A. gossypii development and survival are unknown and would be useful in helping interpret population dynamics and devising management tactics for this pest. In this paper, the effect of temperature on the life table of A. gossypii reared on cotton was evaluated under laboratory conditions using temperatures of 18, 21, 24, 27, and 30 °C. The developmental rate of immatures increased exponentially from 18 to an optimum around 27 °C and then declined. The estimated lower developmental threshold was 8.0 °C, and 107.5 degree days were required for development from the first instar to adult. The percentage survival of immature stages varied from 81 to 91 % within the range of 18-27 °C. Survival declined to 27 % at 30 °C. The average longevity of adult females was 15.7, 11.7, 8.2, 5.2, and 2.8 days, and the average number of offspring produced per female was 46, 38, 20, 14, and 0, at temperatures of 18, 21, 24, 27, and 30 °C, respectively. From 21-27 °C, the intrinsic rate of increase of A. gossypii was significantly higher than at 18 °C, indicating that 21–27 °C was within the optimal range for the growth of A. gossypii, and that 30 °C constant is beyond the upper limit for reproduction. The observations will form the basis of a forecasting system and could account for the decline of the species on cotton in central Asia as well as other regions during hot summer months.