Hydrolysis of Glycosidically Bound Volatiles from Apple Leaves (Cv. Anna) by Aspergillus niger β-Glucosidase Affects the Behavior of Codling Moth (Cydia pomonella L.)

Glycosidically bound volatiles released from apple leaf extracts (cv. Anna) were analyzed by solid-phase microextraction−gas chromatography−mass spectrometry (SPME−GC−MS) and their behavioral effects on codling moth (CM) adults were evaluated in cage bioassays. The levels of 1-octanol, linalool, geraniol, benzyl alcohol, methyl salicylate, (2R,5R)-theaspirane, and (2S,5R)-theaspirane were significantly increased in the leaf extracts containing the Aspergillus niger β-glucosidase (BGL1) compared to the extracts containing the glucoimidazole. The attractiveness of individual compounds to CM adults was found in the following decreasing order: methyl salicylate and mixture of two theaspirane isomers, followed by linalool and benzyl alcohol. Geraniol was found to be repellent to CM adults. The addition of geraniol (39.4 ng mL-1) to any of the individual volatiles or to a mixture of these attractants eliminated their attractiveness. Our data suggest the possible application of geraniol as a repellent and methyl salicylate or theaspiranes as attractants for the integrated control of CM in apple orchards. Keywords: β-Glucosidase; glycosides; volatiles; geraniol; codling moth; repellent