The efficacy of an improved form of the mass‐trapping method for the control of the olive fruit fly, Bactrocera oleae (Gmelin) was tested for 4 years in a pilot test at Tanagra Voeotia, Greece. Improvements consisted of the extension of the active life of the toxic trap used, active life referring both to its attracting and killing properties, as well as in trap deployment, which combined efficacy and low cost. The method was compared to bait sprays applied from the ground, which constitutes the current standard method for the control of this pest. Both pest population density and fruit infestation levels, the main parameters used for the evaluation of the two methods were considerably lower during all 4 years of tests in the orchards protected by mass trapping compared with those in the orchards protected by bait sprays. Furthermore no complementary measures were required in the mass‐trapping orchards for acceptable crop protection, which was not the case under certain conditions, prior to the introduction of the recent improvements. The cost of the mass‐trapping method was approximately US$ 0.40 per tree per year compared with US$ 0.35 for bait sprays (figures of the Greek Ministry of Agriculture). However, the mass‐trapping method reduces the amount of insecticide used for olive protection by 99.5% (15 mg a.i. per tree per year as opposed to 3 g in the case of bait sprays). A considerable reduction in the cost of the mass‐trapping method is expected with the extension of its use and the mass production of materials used, especially traps.

1,7-Dioxaspiro[5.5]undecane (olean), the major component of the female sex attractant pheromone blend of the olive fruit flyDacus oleae (Gmelin) was shown to be released as a racemate. The response of males and females to pure (R)-(-) and (S)-(+)-enantiomers was tested under laboratory and field conditions. Males in laboratory and field tests responded only to (R)-(-)-olean, which functions as a sex attractant. Females responded only to (S)-(+)-olean in laboratory tests but not in the field. There are indications that the latter enantiomer fuctions as a short-range arrestant throughout the day and as an aphrodisiac in the process of mating.

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Male olive fruit fly attraction to the four synthetic components of the female sex attractant pheromone was studied under laboratory and field conditions. In laboratory tests males responded to all four components tested separately. Component I, (1,7-dioxaspiro[5.5]undecane) was more attractive than any of the remaining three components alone, but a combination of all four was more attractive than component I alone. In field tests with polyethylene vials as pheromone dispensers, the complete mixture, although not statistically significant, was constantly more attractive to males than component I alone. A tendency of enhancement of attraction of component I by combining it with component II (α-pinene) or III (n-nonanal) was also observed. In field tests with rubber septa as pheromone dispensers only component I was attractive. Mixtures containing component I were also attractive but not more attractive than component I alone. Evaporation rate and ratio of components as they come out of the dispenser appear to be critical for male response.

A 2‐year pilot test in Kassandra (Northern Greece) showed that the olive fly infestation was maintained at low levels by a technique that combined 2 bait sprays followed by weekly releases of gamma sterilized flies reared artificially in the lab. The 1st spray was with Lebaycid while the 2nd, 3 weeks later, with Dimecron®. Releases started 2 weeks after the 2nd spray. The release area was about 0.4 km2 with ca. 600 olives trees. Two control olive groves were located near the release area, the nearest at a distance of ca. 1,000 m from its periphery. Sterilized flies were released from the ground. In the 1st year, flies were irradiated at the adult stage while in the 2nd at the pupal stage in nitrogen. Releases started before fruits became suitable for oviposition and stopped in November when cold weather diminished fly activity. Of major importance was found to be the timing of spray and releases. In the 1st year a major problem was fungal infestations accentuated by the excessive stinging of fruits from released females. In the 2nd year we had no such problem since insects were sterilized at the pupal stage and thus did not produce eggs. Zusammenfassung Untersuchungen zur Kontrolle der Olivenfliege, Dacus oleae (Cmel.) Zweijährige Versuche auf der Halbimel Kassandra (Nord‐Griechenland) haben gezeigt, daß der Olivenfliegenbefall niedrig gehalten werden konnte, wenn eine Technik angewendet wurde, die aus zwei Insektizid‐Köder‐Spritzungen und wöchentliche Freilassungen von künstlich gezüchteten sterilen Fliegen (Co60 γ‐Strahlen) bestand. Der erste Insektizid‐Einsatz erfolgt mit Lebaycid, der zweite mit Dimecron®. Die Freilassung von Fliegen folgte 2 Wochen nach dem zweiten Insektizid‐Einsatz. Das Versuchsfeld hatte 600 Bäume und war 0,4 km2 groß. Zur Kontrolle dienten 2 Olivenhaine, die über 1000 m vom Freilassungsgebiet entfernt waren. Die sterilen Fliegen wurden aus dem Boden freigelassen. Im ersten Versuchsjahr wurden die Fliegen als Jungadulten, im zweiten als späte Puppen in Stickstoff bestrahlt. Die Freilassung von Fliegen begann, ehe die Olivenfrüchte befallsreif waren und endete im November, wenn das kalte Wetter die Flugaktivität der Fliegen beendete. Sehr wichtig für den Erfolg war die Bestimmung der richtigen Zeit für den Insektizid‐Einsatz und die Freilassung. Im ersten Jahr bildete ein pilzlicher Befall der Früchte ein Problem, der im Zusammenhang mit den zahlreichen Stichen stand, welche die freigelassenen Weibchen in die Früchte bohrten. Im zweiten Jahr bestand dieses Problem nicht, weil die Fliegen als spate Puppen bestrahlt wurden und die Weibchen keine Eier produzierten, so daß die Anstiche wesentlich reduziert wurden.