RECIPROCAL MOVEMENT OF GRAPE PHYLLOXERA (HOMOPTERA, PHYLLOXERIDAE) ALATES AND CRAWLERS BETWEEN 2 DIFFERENTIALLY PHYLLOXERA-RESISTANT GRAPE CULTIVARS

Grape phylloxera, Daktulosphaira vitifoliae (Fitch), alates and crawlers (apterae) were trapped in adjacent vineyard blocks of 'Aurore' and 'Concord' grapes (Vitis spp.) in New York in 1986-1987. Aerial sticky traps were mounted on poles at three heights above the trellis, and ground sticky traps were placed with the sticky trap surface facing upward or downward at several locations in both vineyard blocks. The abundance of aerially trapped crawlers was much higher in the 'Aurore' block than in the 'Concord' block but declined as distance from the 'Aurore' block increased. More alates were captured in the 'Concord' block in both years, and traps in the 'Aurore' block nearest the 'Concord' block captured greater numbers of alates than did traps further from the 'Concord' block. The level of grape root infestation was determined in each block in 1987. The 'Concord' block had greater root infestation than the 'Aurore' block, and the infestation levels of both blocks increased through the growing season. Late-season root samples taken in regions of the 'Concord' block nearest the 'Aurore' block had higher root infestations than root samples taken farther from the 'Aurore' block. These results suggest that the 'Concord' block is a source of alates that move to the susceptible foliage of the 'Aurore' block and that the 'Aurore' block is a source of crawlers that move to the roots of the neighboring 'Concord' block.