Insecticidal activity of strains of Bacillus thuringiensis on larvae and adults of Bactrocera oleae gmelin (Dipt. Tephritidae)

The olive hy Bactrocera oleae, is the key pest on olives in the Mediterrane an area. The pest can destroy in some cases, up to 70% of the olive product ion. Its control relies mainly on chemical treatments, sometimes applied by aircraft over vast areas,with their subsequent ecological and toxicologica l side effects. Bacillus thuringiensis is a spore-forming soil bacterium wh ich produces a protein crystal toxic to some insects, including the orders of Lepidoptera, Diptera, and Coleoptera and other invertebrates. The aim of this study was to search for isolates toxic to B. oleae. Several hundred B . thuringiensis isolates were obtained from olive groves and olive presses in different areas of Greece, Sardinia (Italy), and Spain and from cooperat ing scientists throughout the world. Some isolates were found toxic only to adults or larvae and some to both stages of the olive fly In addition, the most toxic isolates were assayed on Opius concolor Szepl. (Hym, Braconidae ), the most important parasitoid of the olive fruit fly. Only 3 isolates ou t of 14 gave significant mortality against this parasitoid. Several of the most toxic crystalliferous isolates may contain novel toxins since they gav e no PCR products when probed with primers specified for 39 known toxin gen es. (C) 1999 Academic Press.