Effect of fluctuating and constant temperatures on different population growth parameters of Chilo partellus (Swinhoe) infesting sorghum was studied in the laboratory. On the basis of intrinsic rate of natural increase (rm) values, the optimum constant and fluctuating temperatures for the multiplication of this pest was 30 ± 1°C and 31.0 to 35.8°C, respectively. But the favourable range of temperature varied from 27.5 to 30.0°C under both constant and fluctuating temperature conditions. Mean length of generation (T) at this range of temperature varied from 38 to 41 days. It seems that Chilo partellus may not persist at or above 40°C and below 20°C, as the rm values at these temperatures were negligible or zero. This information can be used in working out the strategy for controlling Chilo partellus.
