Submitted to: Environmental Entomology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 4/26/2011
Publication Date: 8/11/2011
Publication URL: http://handle.nal.usda.gov/10113/53743
Citation: Silk, P.J., Rayall, K., Mayo, P., Lemay, M.A., Grant, G., Crook, D., Cosse, A.A., Fraser, I., Sweeney, J.D., Lyons, D.B., Pitt, D., Scarr, T., Magee, D. 2011. Evidence for a volatile sex pheromone in Agrilus planipennis Fairmaire (Coleoptera: Buprestidae) that synergizes attraction to a host foliar volatile. Environmental Entomology. 13:904-916. Interpretive Summary: The emerald ash borer (EAB), Agrilus planipennis, is the most destructive invasive insect to impact U.S. forests. Native to Asia, it was discovered in the U.S. in 2002. Since then EAB has been found in 15 states and killed tens of millions of ash trees (Fraxinus spp.), destroying 99.9% of ash trees in an area. Without intervention, the entire North American ash resource is at risk. Current EAB detection methods, especially in low infestation areas, rely heavily on visual surveys and the use of girdled trap trees to detect the presence of the beetles. Both methods are labor intensive and relatively expensive, and improved methods of beetle detection are urgently needed. Attractant-baited traps have been used to monitor insect pest populations for a wide range of insect species, both in agricultural as well as in forestry settings. The pheromone attractant used in this study could benefit the monitoring trapping systems and are currently under development for the detection of EAB.
Technical Abstract: Analysis by gas chromatography/ mass spectrometry (GC/MS) of volatiles from virgin female emerald ash borer, Agrilus planipennis Fairmaire, confirmed the emission of (3Z)-lactone [(3Z)-dodecen-12-olide] but not its geometric isomer, (3E)-lactone [(3E)-dodecen-12-olide]. Gas chromatographic/ electroantennographic (GC/EAG) analysis of synthetic (3Z)-lactone, which contained 10% (3E)-lactone, showed a strong response of male and female antennae to both isomers. EAG analysis with 0.01-100 µg dosages showed a positive dose-response with females giving significantly higher responses than males. In field experiments with sticky purple prism traps, neither lactone isomer affected catches when combined with ash foliar or cortical volatiles (green leaf volatiles or Phoebe oil, respectively). However, on green prism traps, the (3Z)-lactone significantly increased capture of male A. planipennis when traps were deployed in the canopy. Captures of males on traps with both (3E)-lactone and (3Z)-hexenol or with (3Z)-lactone and (3Z)-hexenol were increased by 45-100%, respectively, as compared to traps baited with just (3Z)-hexenol. In olfactometer bioassays, males were significantly attracted to (3E)-lactone, but not the (3Z)-lactone or a 60:40 (3E):(3Z) blend. The combination of either (3E)- or (3Z)-lactone with Phoebe oil was not significantly attractive to males. Males were highly attracted to the (3Z)-hexenol and the (3Z)-lactone + (3Z)-hexenol combination, providing support for the field trapping results. These data are the first to demonstrate synergy in attraction of a sex pheromone and green leaf volatile in a Buprestid species.