Oviposition response and development of the egg-pupal parasitoid Fopius arisanus on Bactrocera oleae, a tephritid fruit fly pest of olive in the Mediterranean basin

To date, information is wanting with regard to the use of new exotic parasitoids against olive fruit fly, Bactrocera (=Dacus) oleae (Gmelin) (Diptera: Tephritidae), a serious pest of olives Olea europaea L., in the Mediterranean basin. We investigated the oviposition response and developmental biology on B. oleae of Fopius (=Biosteres) arisanus (Sonan) (=Opius oophilus Fullaway) (Hymenoptera: Braconidae), an egg-pupal parasitoid of tephritid fruit flies, never tested before as a potential parasitoid of this host. Our results showed that olive fruits infested with B. oleae eggs exerted a relevant attraction to gravid F. arisanus and represented a stimulus for oviposition. Nevertheless they were not as attractive to female parasitoids as the Mediterranean fruit fly, Ceratitis capitata Wiedemann (Diptera: Tephritidae), eggs infested papaya fruits (Carica papaya L.). In our experimental conditions, F. arisanus completed development in B. oleae within 33 ± 1.7 days (males) and 35 ± 1.6 (females). Increases in host egg to female parasitoid ratios of 1:1, 5:1, 10:1 and 20:1 corresponded with decreases in the percentage of B. oleae parasitisation and host killing but corresponded also with increases in absolute parasitisation. Our findings are discussed in light of possibilities of utilising F. arisanus for biological control of olive fruit fly.