CLONE AND LEAF POSITION EFFECTS ON POPULUS DEFOLIATION BY LEAF-CUTTING BEES (HYMENOPTERA, MEGACHILIDAE)

The effects of clone and leaf position within a shoot on percent defol iation by a leaf-cutting bee (Hymenoptera: Megachilidae), were examine d. Seven Populus clones (Populus X euramericana 'Norway', 'Robusta', a nd 'Imperial'; Populus X jackii 'Northwest'; Populus fremontii var. wi slizenii Wats. 'Rio Grande'; Populus deltoides var. 'Siouxland'; Popul us deltoides X Populus nigra 'Italica'-14271) were tested for their su sceptibility to leaf-cutting bees. Defoliation measurements were taken for each individual leaf position for one shoot of each tree for four sampling periods. A two-way ANOVA was used to test for the effects of clone and leaf position on defoliation. There were significant differ ences among the clones. Leaf positions 7-9 were more heavily defoliate d than any other leaf position. Leaf position preferred by leaf-cuttin g bees varied consistently among Populus clones.