OLEA-EUROPAEA CHEMICALS REPELLENT TO DACUS-OLEAE FEMALES

The egg dispersion strategy of the olive fruit fly Dacus oleae, which is dependent on chemicals from the fruit, was investigated. In particu lar, the exact role of o-diphenolic compounds, such as the typical oli ve glucosides, oleuropein and deniethyloleuropein, and their derivativ es was clarified. It appears that the strong chemotactile repulsive ef fect exerted by the water fraction of crushed olives is due mainly to (E)-2-hexenal. Several compounds, such as beta-3,4-dihydroxyphenyletha nol and other oleuropein derivatives, which exert a strong chemotactil e repulsion, were newly identified or confirmed either in fresh olive juice or in olive mill waste water. This result confirms that the smal l droplets of olive juice, regurgitated just after egg laying by the D . oleae female all around the oviposition hole, actually prevent other females from ovipositing on the same fruit.