Abstract :
The present investigation aimed to study the effect of four constant temperatures (17, 22, 27 and 32°C) on the developmental rates of different stages of cotton leafworm, Spodoptera littoralis. The incubation period, larval duration, pupal duration, pre-oviposition period and duration of generation were estimated. The time required for development was decreased as the temperature increased. The threshold temperatures were 11.8°C for egg, 7.56 °C for larvae, 12.27 °C for pupae, 12.58°C for the pre-oviposition period, and 10.5 °C for a generation. The average thermal requirements needed for completing the development were 40.1, 283.76, 149.5, 23.96 and 480.6 degree-days for egg, larvae, pupae, pre-oviposition period and generation; respectively.
Keyword :
Temperatures, leafworm, Spodoptera littoralis. thermal requirements