The weevil Oxyops vitiosa is an Australian species imported to Florida, USA for the biological control of the invasive species Melaleuca quinquenervia. The larvae of this species feed on the leaves of their host and produce a shiny orange secretion that covers their integument. When this secretion is applied at physiological concentrations to a dog food bait, fire ant consumption and visitation are significantly reduced. Gas chromatographic analysis indicates that the larval secretion resembles qualitatively and quantitatively the terpenoid composition of their host foliage. When the combination of the ten major terpenoids from the O. vitiosa secretion were similarly applied to dog food bait, fire ant consumption and visitation were reduced. When these ten terpenoids were similarly tested individually, the sesquiterpene viridiflorol was the most active component decreasing fire ant consumption of dog food bait. Fire ant visitation was initially (15 min after initiation of the study) decreased for dog food bait treated with viridiflorol, and the monoterpenes 1,8-cineole, and a-terpineol. Fire ants continued to avoid the bait treated with viridiflorol at 18 µg/mg dog food for up to 6 hrs after the initiation of the experiment. Moreover, ants avoided bait treated with 1.8 µg/mg for up to 3 hrs. The concentrations of viridiflorol, 1,8-cineole, and a-terpineol in larval washes were about twice that of the host foliage suggesting that the larvae sequester these plant-derived compounds for their defense against generalist predators.
Species 1: Coleoptera Curculionidae Oxyops vitiosa (Melaleuca leaf weevil)
Species 2: Hymenoptera Formicidae Solenopsis invicta (red imported fire ant)
Keywords: host selection, specificity
The ESA 2001 Annual Meeting - 2001: An Entomological Odyssey of ESA