HOST-USE PATTERNS OF CAPITULUM-FEEDING INSECTS OF YELLOW STARTHISTLE - RESULTS FROM A GARDEN PLOT IN GREECE

More than 15 species of capitulum-feeding insects colonized a randomized garden plot of yellow starthistle, globe artichoke, cultivated safflower, and Cirsium creticum (Lam.) D'Urv. in northern Greece in 1985. Among these insects were seven potential bio-control agents of yellow starthistle: the cynipid wasp, Isocolus sp.; the tephritid flies, Chaetorellia australis Hering, Terellia uncinata White, and Urophora sirunaseva (Hering); and the curculionid beetles, Bangasternus orientalis (Capiomont), Eustenopus villosus (Boheman), and Larinus curtus (Hochhuth). These potential agents only attacked yellow starthistle plants, which were grown from seed collected in Greece and the United States. This host specificity data was used to justify the subsequent release of C. australis and E. villosus in the United States. The relative intensity of interspecific interactions among capitulum-feeding insects of yellow starthistle is discussed, as well as the potential effectiveness of E. villosus as a biocontrol agent. This study points to the usefulness of the open field test in host specificity determination of insects for biological control of weeds.