BORNEOL AS AN ATTRACTANT FOR CYZENIS-ALBICANS, A TACHINID PARASITOID OF THE WINTER MOTH, OPEROPHTERA-BRUMATA L (LEPIDOPTERA, GEOMETRIDAE)

Volatile compounds were isolated and identified from a crude extract o f garry Quercus garryana, foliage which was known to be attractive to the tachinid fly Cyzenisis albicans. Candidate compounds were identifi ed by the combined use of gas chromatography-mass spectrometry, and in fra-red spectroscopy. Specific oak-leaf volatiles were field-tested in 2 different years in an apple orchard. Compounds were applied singly or in combination to individual apple trees; the number of C. albicans entering the canopy,of each tree was observed and the number of eggs they oviposited on foliage was estimated. Borneol was the only compoun d that attracted flies when compared with the other treatments, but th is did not result in more fly eggs being oviposited on borneol-treated trees. None of the compounds tested resulted in a greater number of C yzenis eggs being oviposited. A greater abundance of borneol in oak fo liage than in apple foliage, and its attractiveness to C. albicans, ma y explain the aggregation of flies in response to feeding-damage among oak trees and the absence of this pattern among apple trees.