Olive Fly (Bactrocera oleae Gmelin) Population Dynamics in Terceira Olive Groves (Portugal)

In the Azores Archipelago (Portugal), the olive tree only grows on two islands, Terceira and Pico. According to the 2008 area production census, Terceira Island has about 12 hectares of olive tree production, limited to the Porto Martins village area, and all olive production is for direct consumption (table olives). The main phyto-sanitary problems that are causing damage in Terceira olive productions are: olive fly (Bactrocera oleae Gmelin.), olive moth (Prays oleae Bern.), black scale (Saissetia oleae Oliv.) and a new phytosanitary problem that was detected only in 2008, the olive psylla Euphyllura olivina Costa. The olive fly (B. oleae) is the key pest of this culture in Terceira Island due to fruit damage. Next in rank is the olive moth (P. oleae). For monitoring and risk analysis purposes, during July 2009, several traps with food attractant (diamonic phosphate) were placed in two distinct orchards. One was treated and the other was completely without any kind of treatment. The traps were checked every 15 days and the B. oleae adult captures were recorded at that time interval. According to the collected data, from July to November 2009, the adult B. oleae population peak occurred during September and November. The fruit damage analysis regarding the B. oleae adult activity in 2009 indicated that there is was 86% of fruit infestation/damage in the treated olive orchard versus 99% of fruit infestation/damage in the non-treated olive orchard. The collected field data allowed the development of charts to visually identify the time periods of the major adult population of B. oleae. These results will allow better decision making to reduce the high levels of infestation as well as the high number of phytosanitary treatments that are on-going during olive production season.