MORPHOLOGICAL ADAPTATION TO DIFFERENT ARTIFICIAL OVIPOSITION SUBSTRATES IN THE ACULEUS OF CERATITIS-CAPITATA (DIPTERA, TEPHRITIDAE)

Artificial oviposition substrates with various perforation diameters were used to study changes in aculeus anatomy of Ceratitis capitata (Wiedemann). A laboratory strain, selected to oviposit into a small-mesh substrate with mean perforation diameter (MPD) of 0.19 mm, was compared with parental stock (line 1) which was adapted to oviposit into perforated plastic containers with 0.31 mm MPD. The aculeus widths of the laboratory strain were significantly narrower than those of the parental stock in the 12th and 22nd generations. To confirm these results, two additional strains were established from the parental stock by using different MPD substrates (0.19 and 0.27 mm). Aculeus widths were studied for each of 10 generations in these strains. Aculei were significantly narrower in both additional lines than in the parental stock. When laboratory strains were compared with wild flies, the aculei of wild strains were significantly narrower than those of laboratory flies. The significance of directional selection for the narrowed aculei in laboratory flies is discussed with reference to the aculeus widths of wild flies.