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

The effect of nine phenylalanine and tyrosine analogues at various concentrations upon the reproduction of adult olive fruit fly Bactrocera oleae Gmelin (Diptera, Tephritidae), was tested. Fecundity (eggs/female/day) and percentage egg hatchability was significantly reduced by the following anti-amino acids (in parentheses are indicated the antagonized amino acid): p-fluoro-DL-phenylalanine (phe), p-amino-DE- 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 other 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-tyrosine at concentrations 0.25 and 6%, respectively. No significant differences were observed between the survival of the two sexes. Finally, β-2-thienyl-DL-alanine (phe) and α-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 containing p-amino-L-phenylalanine and 3-amino-L-tyrosine, revealed abnormalities related to the eggshell fine structure

Survival, fecundity and fertility of Bactrocera oleae, as affected by amino acid analogues

The effect of twenty five amino acid analogues at various concentrations upon the adult olive fruit fly Bactrocera oleae Gmelin (Diptera: Tephritidae), was tested. Insect survival was significantly shortened by the following amino acid analogues: (in parentheses are indicated the antagonized amino acids) D-cycloserine (alanine), L-glutamic acid-γ-hydrazide (glutamine), DL-allyl-glycine (cysteine), L-canavanine (arginine), L-methionine-DL-sulfoximine (methionine) and 3,4-dehydro-DL-proline (proline). Fecundity was significantly reduced by the same analogues plus aminoethanesulfonic acid (glycine), taurine (alanine), L-norvaline (leucine), a-methyl-DL-serine (serine), DL-hydroxyglutamic acid (glutamic acid), (S)-2-(aminoethyl)-L-cysteine (lysine), a-methyl-DL-methionine (methionine) and a-methyl-DL-histidine (histidine). All the above amino acid analogues also depressed egg-hatching with the exception of taurine, DL-hydroxyglutamic acid, DL-allyl glycine, a-methyl-DL-methionine and a-methyl-DL-histidine. Finally, y-glutamyl-p-nitroanilide (glutamic acid), crotyl-glycine (methionine), DL-7-azatryptophan and 5-methyl-DL-tryptophan (tryptophan), DL-1,2,4 triazole-3-alanine (histidine) and DL-pipecolic acid (proline) did not affect any of the parameters tested

Egg laying suppression in Drosophila melanogaster (Diptera: Drosophilidae) and Dacus (Bactrocera) oleae (Diptera: Tephritidae) by phloroglucinol, a peroxidase inhibitor

Eggshell peroxidase (ESP) is responsible for the hardening process in several Diptera, including Drosophila melanogaster Meigen and Bactrocera oleae Gmelin. Its action can be inhibited by phloroglucinol, a natural phenolic substance, during the formation of the egg-shell. We used phloroglucinol, in the diet of adults of D. melanogaster and B. oleae, at concentrations of 1 mM, 10 mM, 25 mM, 50 mM, 100 mM and 400 mM to study its effect on egg laying. In both insects, 1 mM had no effect. At concentrations above 10 mM, egg laying of D. melanogaster was gradually affected leading to the deposition of empty shells and chorion-less eggs, while in B. oleae, it was gradually suppressed and only amorphous masses were laid. The effect of phloroglucinol at the tested concentrations was reversible. It is concluded that phloroglucinol added at appropriate, non-lethal concentrations, affected egg-laying of D. melanogaster and B. oleae in different ways, related to differences in the ovipositor diameter relative to egg size. In B. oleae, it is relatively narrow, causing breakage of the phloroglucinol-induced non-elastic egg-shell, since covalent crosslinking of the chorion proteins is prevented. In D. melanogaster, chorion-less eggs and separate chorions are laid, due to egg dechorionation. A possible field application of these results is discussed