Parasitism of Bactrocera oleae (Diptera; Tephritidae) by Psyttalia concolor (Hymenoptera; Braconidae) in the Balearic Islands (Spain)
Psyttalia concolor (Hymenoptera; Braconidae) was introduced to Spain in the early 1970s to control the olive fruit fly Bactrocera oleae. Previous studies showed that P. concolor was poorly adapted to temperate zones, such as the Balearics. In this study, we demonstrate a high rate of natural parasitism of B. oleae by P. concolor in Majorca (Balearic Islands). Surveys were carried out from August to September 2007 in two organically-farmed olive orchards and two insecticide-managed orchards. A total of 250 olive fruits were examined weekly from each of the orchards. Olives were kept under laboratory conditions until the emergence of B. oleae pupae, which were collected and placed in Petri dishes until the emergence of B. oleae and/or P. concolor adults. In addition, red sticky spheres and yellow sticky panel traps were placed in every orchard for monitoring adults of P. concolor. Red spheres captured more individuals of the parasitoid when compared with the yellow panels. Seasonal average parasitism levels of B. oleae pupae by P. concolor were high (22.4% and 23.4%) in the two organically-farmed orchards and 0% in the insecticide treated orchards. The high rates of parasitism by P. concolor found in the organically-farmed olive orchards supports the use of this parasitoid for the biological control of B. oleae in the Balearic Islands.