NEW POTENTIAL INHIBITORS OF PHEROMONAL ATTRACTION IN THE ORIENTAL FRUIT MOTH, CYDIA-MOLESTA

New analogues of (Z)-dodec-8-en-1-yl acetate (Z8-12:OAc, 1), the main sex pheromone component of the Oriental fruit moth, Cydia molesta, wer e designed by formally transferring the terminal propyl group from the C-9 to the C-7 position to form vinyl-branched (2, 3) or, after isome rization, ethylidene-branched 4) structures and by replacing the -CH=C H- grouping by the -S-CH2- moiety (5, 6). Their biological activities were studied both electrophysiologically and behaviourally (laboratory mating and wind tunnel experiments). All the structural modifications resulted in analogues whose electroantennographic activities were low er than that of 1 following the order 1 much greater than 6 approximat e to 5 much greater than 2 approximate to 4 approximate to 3. The sing le sensillum recording activities indicated that all the analogues sti mulate the same Z8-12:OAc receptor neurone, In behavioural experiments , the analogues were generally found to reduce the ability of males to find a pheromone source, however, to different degrees. The highest i nhibitory effect (90%) was observed for the thia analogues 5 and 6. Th e results support the view that the inhibitory properties of the analo gues should not be entirely associated with their pheromone-mimicking capabilities.