Arrestment behavior in the polyphagous tropical root weevil Diaprepes abbreviatus.

A semiochemical-based attractant for the tropical root weevil, Diaprepes abbreviatus L., has been sought since the introduction of this polyphagous pest to Florida in the 1960s. A six-unit wind tunnel apparatus was constructed to allow multiple runs to be conducted simultaneously to test the response of D. abbreviatus adults to volatile and contact semiochemicals. Arrestment was measured as the number of weevils stopping and remaining on a target when presented with upwind target choices. No response (movement upwind) was observed when weevils were presented with a control (no odor). Some movement upwind but no arrestment occurred when weevils were presented with young citrus leaves (flush). Citrus flush that had been fed on by D. abbreviatus adults was highly attractive and induced arrestment of both male and female adults. The effect was duplicated by placing organdy-enclosed feces (frass) on undamaged flush. The arrestment effect was eliminated, however, when fed-on flush was enclosed in a cage so that weevils could not contact the leaves. In these experiments, weevils continued to move upwind. The results of these tests lead us to conclude that host and mate location by D. abbreviatus is mediated by volatile and contact semiochemicals.