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Project description
Control of the Olive Fruit Fly (OLFF), Bactrocera oleae, through post-harvest fruit sanitation and spinosad baits (GF-120). (02BU007)
Program UC IPM competitive research grants program
Principal
investigator 		R.A. Van Steenwyk, E.S.P.M., UC Berkeley
Host/habitat Olives; Tree Crops
Pest Olive Fruit Fly Bactrocera oleae
Discipline Entomology
Review
panel 		Biorational Use of Biotic Agents
 Start year (duration)  2002 (Three Years)
Objectives Investigate the effect of post-harvest applications of ethephon on olive fruit and leaf drop.

Investigate the effect of fruit development on OLFF oviposition and survival.

Investigate the efficacy and assist in the registration of spinosad bait (GF-120) on olives.

Investigate the effect of post-harvest ethephon applications on spring emergence of OLFF.

Investigate OLFF population dynamics following applications of ethephon and GF-120.

Final report GF-120 at a 1: 1.5 dilution significantly suppressed OLFF with repeated applications of a weekly schedule at the Mission San Jose under high OLFF pressure in 2004. The experiment should be considered a rigorous test of the material since there was significant reduction in OLFF infestation under extreme population pressure.

Laboratory insecticide trials indicated that full rate cover sprays of Malathion, Success, and all pyrethroids, plus NuLure provided good control of OLFF at 1/2 and 1 DOE. GF-120 also provided good control of OLFF at 1/2 and 1 DOE.

In a field trial, the high rate of Danitol provided effective control of OLFF at 0 DAT. At 3 DAT, both rates of Danitol and GF-120 were similar. By 7 DAT, only Danitol provided partial control. However, inclement weather resulted in termination of the study before the materials could be properly evaluated.

The postharvest application of Ethrel accelerated fruit drop at 600 ppm. However, the higher rates of application also led to leaf drop. It appears that buffering Ethrel decreases phytotoxicity to acceptable levels. Fruit drop needs to be improved to provide effective control.

Fruit that is present for the spring OLFF flight can be oviposited. However, once fruit falls to the ground, it is highly unlikely that OLFF will oviposit on the fallen fruit or that the fruit will produce a viable OLFF.

Third-year
progress 		Unharvested fruit from the previous year can become infested in early spring and produce a spring generation that bridges the olive fruit fly (OLFF) population until the new crop becomes susceptible to attack. However, OLFF will not oviposit on fruit on the ground. Shaking the trees with an almond shaker or blowing the trees with an air-blast sprayer in late winter to early spring removed a majority of unharvested fruit. The postharvest application of 600 ppm Ethrel initially accelerated fruit drop. However, by the end of the evaluations there was little difference in fruit drop between ethephon and control treatments, and ethephon also led to excessive leaf drop. GF-120 at a 1: 2.0 dilution applied twice in the spring suppressed OLFF populations. Also, GF-120 at a 1: 1.5 dilution significantly suppressed OLFF with repeated applications on a weekly schedule in season under a very high OLFF population. Laboratory insecticide trials indicated that full rate cover sprays of malathion, Success, and all pyrethroids plus NuLure provided good control of OLFF at 1/2 and 1 day of exposure (DOE). GF-120 also provided good control of OLFF at 1/2 and 1 DOE. In a field trial, the high rate of Danitol provided effective control of OLFF at 0 days after treatment (DAT). At 3 DAT, both rates of Danitol and GF-120 were similar. By 7 DAT, only Danitol provided partial control.

Second-year
progress 		The postharvest application of Ethrel at 2400, 600 and 300 ppm ethephon significantly accelerated fruit drop, particularly at the 2400 ppm rate. However, there was significantly higher leaf drop over control, particularly at the 2400 ppm rate. The addition of sodium bicarbonate buffer to the Ethrel appeared to have suppressed leaf drop but also fruit drop. Uninfested fruit exposed to OLFF in the field become infested in direct relationship to the adult fly population. Uninfested fruit placed on the ground rapidly desiccated or rotted and apparently did not become infested. Evaluations of the dilution rate of GF-120 indicated that there was no significant difference among three dilutions (1:9, 1:4 and 1:1.5 GF-120:water), although the 1:9 dilution gave numerically consistent lower infestation levels than 1:4 or 1:1.5 dilutions.

First-year
progress 		The post-harvest application of Ethrel significantly accelerated fruit drop, particularly at the higher rates of application (1200 and 2400 ppm ethephon). However, the higher rates of application also led to considerable leaf drop. Research will concentrate on methods of increased fruit drop without increased leaf drop. The repeated applications of GF-120 significantly suppressed OLFF infestation under the extremely high population pressure. The experiment should be considered a rigorous test of the material. Laboratory evaluations of Sevin and Supracide showed that they were ineffective in controlling OLFF. Thus, the only effective registered insecticide for control of OLFF is GF-120.

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