01819nas a2200157   4500008004100000245011100041210006900152300001200221490000600233520118000239653004801419100001901467700002101486700002301507856013101530       1995                        eng d00aOpen-field host-specificity testing for potential biological control agents  of <i>Onopordum </i>thistles.0 aOpenfield hostspecificity testing for potential biological contr  a158-1660 v53 aOpen-field host-specificity tests conducted in Greece and  France demonstrated an absolute preference for Onopordum spp. over Cynara  spp. by four potential biological control agents of Onopordum thistles that  are weeds in Australia, the seed weevils, Larinus latus and L. cynarae, the  seedfly, Tephritis postica, and the stem-boring weevil, Lixus cardui. A fifth  species, the planthopper, Tettigometra sulfurea, showed a strong  ovipositional preference for Onopordum spp., while nymphs hatching from eggs  laid on Cynara spp. did not develop to adulthood. The genus Cynara is  critical to host testing as it is the most closely related genus to Onopordum  and contains economic crop plants. Rejection of Cynara spp. by the potential  control agents justified the expense of continuing host-specificity testing  against an expanded series of plants and has led to the authorization for  field release of two of the above species, L. latus and L. cardui. Where key  plant species can be identified they should be tested first, to reduce the  wastage of resources that occurs when long test programs ultimately lead to  rejection of candidate agents for biological control.10aColeoptera Curculionidae Diptera Orthoptera1 aBriese, D., T.1 aSheppard, A., W.1 aReifenberg, J., M.  uhttps://icgf.myspecies.info/content/open-field-host-specificity-testing-potential-biological-control-agents-onopordum-thistles