Effect of different temperaures, thermal, threshlod units on developmentof silvery moth, Autographa gamma Linn.

Developments of the silver Y moth Autographa gamma Linn (Lepidpterra : Noctuidae) was studied at constant temperatures 20, 25 and 30˚C˚ ±1ْْ ˚C . Development of immature stages was accelerated as the tested temperatures increased .Total developmental time of larval duration averaged 25.26, 19.14 and 12.08 days at 20, 25 and 300Crespectively. Generation period ranged between 46.34and 23.81days depending on rearing temperature. Adult female survived slightly longer than male. Fecundity was higher at (30˚C) than 20˚C. Female of A. gamma deposited 106.67eggs at 30 ˚C, while this number drastically decreased to 18.55 eggs at 20 ˚C. However, egg hatchability was %72.41; 66.04 and 63.64 at 20,25and 30 ˚C respectively.The threshold of development (t0) degree- day (DDs ) was estimated to be 7.5˚C, 10.83˚C and 3.020C for eggs, larvae and pupae, respectively. Based on estimated preferred temperature30,25 and 20 C˚ heat units (U.T. ) 79.2, 362.5and 247.8 are required to complied the development of egg, larval and pupal stages. Development of one generation may acquire 726.4 Degree-days.