Effect of phenylalanine and tyrosine analogues on Bactrocera oleae Gmelin (Dipt., Tephritidae) reproduction

The effect of nine phenylalanine and tyrosine analogues at various concentr ations upon the reproduction of adult olive fruit fly Bactrocera oleae Gmel in (Diptera, Tephritidae), was tested. Fecundity (eggs/female/day) and perc entage egg hatchability was significantly reduced by the following anti-ami no acids (in parentheses are indicated the antagonized amino acid): p-fluor o-DL-phenylalanine (phe), p-amino-DL- and -L-phenylalanine (tyr), 3-amino-L -tyrosine (tyr) and L-mimosine (tyr), at concentrations of 0.1, 0.25, 0.05 and 0.5% in the diet, respectively. Hatchability was also affected by two o ther analogues of phenylalanine and tyrosine, p-bromo-DL-phenylalanine at a concentration of 10% and m-fluoro-DL-tyrosine at a concentration of 1.5%. Insect survival was affected only by p-fluorophenylalanine and 3-amino-L-ty rosine at concentrations 0.25 and 6%, respectively. No significant differen ces were observed between the survival of the two sexes. Finally, beta -2-t hienyl-DL-alanine (phe) and a-methyl-DL-p-tyrosine (tyr) did not affect any of the parameters tested. Electron microscopy examination of the follicles and the egg-shell structure of eggs laid by females fed with diets contain ing p-amino-L-phenylalanine and 3-amino-L-tyrosine, revealed abnormalities related to the eggshell fine structure.