Title: Discovery and characterization of chemical signals for citrus root weevil, Diaprepes abbreviatus Authors
Submitted to: Arthropod-Plant Interactions
Publication Type: Abstract Only
Publication Acceptance Date: February 26, 2009
Publication Date: March 31, 2009
Citation: Otalora Luna, F., Hammock, J., Alessandro, R.T., Lapointe, S.L., Dickens, J.C. 2009. Discovery and characterization of chemical signals for citrus root weevil, Diaprepes abbreviatus. Arthropod-Plant Interactions. 3:63-73. Technical Abstract: The tropical root weevil Diaprepes abbreviatus (L. 1758) (Coleoptera: Curculionidae) is a polyphagous insect from the Caribbean Islands and an invasive insect in the southern part of United States where it is pest of citrus crops and ornamental trees. Adults feed upon foliage where aggregation, mating and oviposition take place. Here, the headspace volatiles from Citrus macrophylla Wester (Rutaceae), a hostplant of D. abbreviatus, and adults feeding on this plant, were collected by aeration and solid-phase microextraction (SPME) then analyzed by gas chromatography-linked mass spectrometry (GC-MS). Electrophysiological responses of weevil antennal receptors to volatile headspace extracts and synthetic compounds were recorded by gas chromatography-linked electroantennographic detection (GC-EAD) and electroantennograms (EAGs). Separation of volatiles using GC revealed a preponderance of monoterpenes in the headspace of citrus leaves and adults feeding on the leaves. Antennal responses were recorded to (R)-(-)-linalool, citronellal, nerol, citral and carvacrol. When comparing EAGs between (+/-)-linalool and (R)-(-)-linalool, no significant difference was found; responses to (R)-(+)-citronellal were larger than for (S)-(-)-citronellal. An open T-track dual choice olfactometer measured behavioral responses to electrophysiologically active compounds and several blends. Among the individual compounds and blends tested, only the blend of (+/-)-linalool, cis-3-hexen-1-ol and carvacrol (source dose 25:25:2.5 µg) elicited significant attraction. The biologically active compounds found here likely play a role in host finding by D. abbreviatus and other interactions of the insect with its hostplant.