Resistance among populations of yellow starthistle to thistle-head insects: results from garden plots in Italy.

摘要: Abstract Variation in resistance to thistle-head insects was studied plants of Centaurea solstitialis L. (yellow starthistle) derived from Nearctic and Palearctic populations grown common gardens near Rome, Italy. Significant variation found the percentage insect-damaged flowerheads among plant populations, with aggregate rates herbivory higher on local (Italian) population. Two tephritid flies, Acanthiophilus helianthi (Rossi) Chaetorellia succinia (Costa), accounted for most damage all populations. In addition, more species exploited capitula Italian (eight vs three six other populations). That only were suitable host Urophora jaculata Rondani suggests a host-plant factor responsible failure this fly become established yellow starthistle California. These results indicate that are not equally susceptible by insects. On hand, adults two potential biocontrol agents, U. quadrifasciata (Meigen) Terellia uncinata White, emerged American plants; thus, there is reason believe these flies would establish related differences size. The overall consistent findings ecologists noncrop vary significantly their individual herbivore groups insect herbivores. also point usefulness open field approach host-specificity determination biological control weeds.