Identification of a Sex Pheromone Component for the Blueberry Leafminer, Caloptilia porphyretica

Abstract

Coupled gas chromatographic-electroantennographic detection (GC-EAD) of both gland extracts and effluvial collections from female blueberry leafminer, Caloptilia porphyretica Braun (Lepidoptera: Gracillariidae), showed that females produced a single EAD-active compound. The amount of the compound collected from virgin female C. porphyretica was below GC and mass spectrometry (MS) detection thresholds, even with highly concentrated gland extracts (approximately 150 female equivalent). (E)-11-Hexadecenal (E11-16:Ald) was determined to be a sex pheromone component mainly by comparison of retention times with authentic standards on both polar and nonpolar capillary columns, microreaction-GC-EAD analyses, and field trapping tests. GC-EAD experiments showed that synthetic E11-16:Ald exhibited extraordinarily high electrophysiological activity, stimulating significant male antennal responses at as low as 10 fg. Traps baited with E11-16:Ald alone were attractive to males. Addition of 1 or 3% of its geometric isomer, Z11-16:Ald, to E11-16:Ald did not significantly increase trap captures, but an inhibitory effect was observed at the 10% level. The influence of two kinds of rubber septa on attraction was also evaluated. Male moth captures were higher in traps baited with red rubber septa than with gray rubber septa at 30-300-microg doses. Monitoring of adult flight activity with 3-microg doses of E11-16:Ald indicated at least three distinct flight periods throughout the 2003 season.