Electrophysiological and behavioural responses of Scyphophorus acupunctatus (Col., Curculionidae) to Agave tequilana volatiles

The weevil Scyphophorus acupunctatus Gyllenhal (Col., Curculionidae) is the most important insect pest of cultivated agaves in Mexico. The objective of this study was to search for potential attractants for this weevil species from the freshly cut fleshy leaves of healthy Agave tequilana Weber var. Blue plants. Combined gas chromatography-electroantennography (GC-EAD) analysis of A. tequilana volatile extracts showed that seven peaks elicited antennal responses from males and females. Five of these peaks were identified by gas chromatography-mass spectrometry (GC-MS) as [omicron]-xylene, [alpha]-pinene, 3-carene, [gamma]-terpinene and linalool. Electroantennogram (EAG) records of both sexes to 1-, 10- and 100-[mu]g-stimulus load of these five compounds showed that there was a dose effect on the EAG responses for linalool, 3-carene and [alpha]-pinene, but not for [gamma]-terpinene and [omicron]-xylene. There were no sexual differences between male and female EAG responses to any of the compounds tested. Y-tube olfactometer bioassays of the compounds showed that males and females were attracted to [alpha]-pinene, 3-carene, [gamma]-terpinene and/or linalool at doses of 1 and 10 [mu]g, while weevils were repelled by linalool at a dose of 100 [mu]g.