History and Objectives: Life span and its increasing in human and its decreasing in pathogenic and harmful organisms has attracted many scientists including genetic. Not enough effort has been made in clarifying the genetics of life span, in some of the previous studies and not enough attention has been made in controlling the environmental effects in others. A different method was performed in this study, focusing on genetics of life span in Drosophila melanogaster at university of Shahrekord (1997-1998).

Materials and Methods: This study in Drosophila melanogaster involved parental, F1, F2 and backcross generations (B1 and B2), derived from crosses between 2 long lived (Mean, 39.5 days) and short lived (Mean, 30.8 days) inbred lines. By performing the variance weighted least square method, the genetic parameters were calculated and the results were tested by using T-test and Chi-Square test.

Results: From 6 genetic parameters employed in experimental model, 5 were significant (P<0.001). These genetic parameters controlling the character were additive [d] and dominance [h] as well as digenic non-allelic interaction components such as additive×additive [i] and dominance×dominance [l]. The accuracy of the 5 parametric model was accepted by obtaining the X² [1]=0.3120 and 0.75>P>0.25.

Conclusion: It was concluded that genetic parameters such as [d], [h], [i] and [l], resulted from nuclear genes actions are involved in controlling the life span. The trigenic interaction and similar complex factors such as extra-nuclear control does not make any significant contribution in genetics of the character. Further studies are needed in clarifying the nuclear genes controlling the character.