IMPORTANCE OF PHENOLIC GLUCOSIDES IN HOST SELECTION OF SHOOT GALLING SAWFLY, EUURA-AMERINAE, ON SALIX PENTANDRA

The effects of phenolic glucosides on the oviposition behavior of Euura amerinae L. (Hymenoptera: Tenthredinidae) were tested in multiple oviposition experiments using different shoot length categories of Salix pentandra L. (with different amounts of phenolic glucosides) and in experiments with pure phenolic glucosides (salidroside, arbutin, salicin, 90% salicortin, 90% 2'-O-acetylsalicortin) or composite total fractions of phenolic glucosides from three willow species (S. pentandra, S. myrsinifolia Salisb., S. triandra L.). This was the first time that the effects of pure phenolic glucosides on the oviposition behavior of sawfly species were tested. Total fraction of phenolic glucosides from S. pentandra and its main individual glucoside, 2'-O-acetylsalicortin, stimulated the strongest ovipositional behavior in E. amerinae. The results show clearly that females of E. amerinae can recognize and choose their host willow, S. pentandra, on the basis of phenolic glucosides. Moreover, they are probably able to use phenolic glucosides as a cue in shoot selection within host-plant individuals.