alpha-Ionone, alpha-ionol, and their mixtures with phenolic volatiles act as potential male lures for the solanaceous fruit fly Bactrocera latifrons (Hendel). However, the attractiveness of these compounds is not as strong as that of other well-known tephritid male lures, such as methyl eugenol for Bactrocera dorsalis. Isophorone and isophorol, which have a partial skeletal structure of alpha-ionone/alpha-ionol (i.e., trimethylcyclohexene), were attractive to B. latifrons males, and their mixtures with alpha-ionol exhibited stronger activity than any of the individual compounds. We also tested 3-oxo-alpha-ionone, 3-oxo-alpha-ionol, 3-hydroxy-alpha-ionone, and 3-hydroxy-alpha-ionol, hybrid compounds between isophorone/isophorol and alpha-ionone/alpha-ionol. 3-Oxo-alpha-ionone and 3-oxo-alpha-ionol were active both as attractants and phagostimulants for males. The results suggest that the introduction of an oxygen atom at the 3-position of the alpha-ionone/alpha-ionol molecule optimizes the specific chemosensory responses in B. latifrons males.
