Evidence for male-produced aggregation pheromone in Sphenophorus incurrens (Coleoptera: Curculionidae)

Sphenophorus incurrens Gyllenhal (Coleoptera: Curculionidae) is an insect that feeds mainly on plants of the family Poaceae in the Neotropics. In Mexico, this weevil is an emergent pest of sugarcane. In this study, first the behavioral responses of both sexes to conspecifics were evaluated in a Y-tube olfactometer. Second, the volatiles of S. incurrens were sampled by the dynamic headspace technique and analyzed by gas chromatography coupled with electroantennographic detection (GC-EAD). Third, the antennal-active compound was identified by gas chromatography coupled with mass spectrometry. Finally, the biological activity of the identified compound was evaluated in laboratory and field tests. Our results showed that males emitted a pheromone that attracts both sexes. The GC-EAD analysis of the male volatiles showed that one peak elicited antennal responses from male and female weevils. The compound was identified as 2-methyl-4-octanol. Laboratory and field tests showed that the identified compound is attractive to both sexes of this weevil species, confirming its pheromonal activity.