Grape Phylloxera Populations Adapted to Vitis berlandieri x V. riparia Rootstocks

Seven grape phylloxera, Daktulosphaira vitifoliae (Fitch), colonies collected from populations on root or leaf galls on the Vitis berlandieri x V. riparia rootstocks SO4, 5BB, and 5C, one colony from the rootstock V. rupestris St. George, and one colony collected from V. vinifera Cabernet Sauvignon were compared in bioassays with excised roots. The colonies were collected in Hungary, Germany, and the United States. The colonies had differing survival, developmental and reproductive capacities when tested on Cabernet Sauvignon, SO4 and 5C in laboratory bioassays. The colonies collected from rootstocks utilized SO4 and 5C roots better than the V. vinifera -collected colony. The performance of the colonies on 5C and SO4 roots was better on callus and nodosities than on tuberosities. This level of utilization of the rootstock roots is likely a result of selection for individuals possessing such traits from a variable population in viticultural situations. Colonies arising from roots or leaves were similarly adapted in the root bioassays. RAPD DNA analysis suggests that the rootstock-collected phylloxera are genetically remote from the V. vinifera collected colony.