Abstract :
drosophila larvare of diffrent speces were subjected to this in order study the structure of cephalopharyngeal armature and mouth more hooks dentition in correlation with their food resources (food habitat) which are more likely genetically controlled. A comparative study of third instar larvae was carried out using a large stock of mass bred population cage which established from fourteen isofemale inbred lines of Drosophila melanogaster Seraleone strain, and eight spccies of Drosophila melanogaster species subgroup, since these species were breeding in laboratory for several generations feeding on yeasted oatomeal medium under room conditions at about 25 ± 1 C°, in addition to the five fungal breeding wild type spccies. The statistical analysis of the results revealed: 1- there was high significant differences in teeth number among the three larval stages of D. melanogaster species which evolutionary reflects the natural development related with the food acquisition for each larval stage. 2- There was a highly significant heterogeneity of variance between the lines, the interesting here was that the average among the lines variance is substantially greater than the sample variance for the mass bred population. 3- Non- parametric test indicated that the differences between the eight species of D. melanogaster spccies subgroup were highly significant, since these species differ in their geographical distribution. 4- The ccphalopharyngeal seclerites and the mouth hooks of the five fungal breeding spccies were more robust and the dentition was larger , so the difference between the five means were significantly high , which may be due to their food resources difference. 5- Inbreeding effects on the stability of mouth tooth number were investigated by comparing the expressing of character in the large cage population and 15 isofemale inbreed strains.
