|Dickens, Joseph - Dick|
Submitted to: Journal of Chemical Ecology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 3/2/2012
Publication Date: 3/21/2012
Citation: Lapointe, S.L., Alessandro, R.T., Robbins, P.S., Khrimian, A., Svatos, A., Dickens, J.C., Otalora-Luna, F., Kaplan, F., Alborn, H.T., Teal, P.E. 2012. Identification and synthesis of a male-produced pheromone for the neotropical root weevil Diaprepes abbreviatus. Journal of Chemical Ecology. 38:408-417. Interpretive Summary: Plant-feeding insects are often able to communicate to locate their food plant and each other using odors called pheromones. These odors can be used to trap them or otherwise interfere with their ability to cause damage. Such a pheromone has long been sought for a damaging invasive pest species named Diaprepes abbreviatus. The Diaprepes root weevil is originally from the Caribbean and is a highly polyphagous pest of plants including citrus. It is now found in Florida, Louisiana and California. ARS scientists discovered a novel molecule, new to science, that is produced by male Diaprepes weevils and is attractive to females of this species. This pheromone was discovered by recording the electronic signals produced by Diaprepes antennae in response to odors collected from males or from their feces. The structure was determined and a synthetic pheromone was produced identical to the natural compound. This new pheromone will now be investigated for use in traps and other methods to control this damaging pest.
Technical Abstract: An unsaturated hydroxy ester pheromone collected from the headspace and feces of male Diaprepes abbreviatus was isolated, identified and synthesized. The pheromone, methyl (E)-3-(2-hydroxyethyl)-4-methyl-2-pentenoate, was discovered by gas chromatography-coupled electroantennogram detection (GC-EAD) and identified by gas chromatography-mass spectrometry (GC-MS) and nuclear magnetic resonance spectroscopy (NMR). The synthetic protocol yielded a 86:14 mixture of methyl (E)-3-(2-hydroxyethyl)-4-methyl-2-pentenoate (1E) and an inactive methyl (Z)-3-(2-hydroxyethyl)-4-methyl-2-pentenoate (1Z) along with a lactone breakdown product 2. The activity of the synthetic E isomer was confirmed by GC-EAD, GC-MS, NMR and behavioral assays. No antennal response was observed to the Z isomer or the lactone. In a two-choice olfactometer bioassay, female D. abbreviatus moved upwind towards the synthetic pheromone or a source of natural pheromone more often compared with clean air. Males showed no clear preference for the synthetic pheromone. This compound, alone or in combination with plant volatiles, may play an important role in the location of males by female D. abbreviatus.