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/EAD) 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- to 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, compared with 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 (3Z)-hexenol and the (3Z)-lactone + (3Z)-hexenol combination, providing support for the field trapping results. These data are the first to demonstrate increased attraction with a combination of a pheromone and a green leaf volatile in a Buprestid species.

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We conducted two trapping experiments in green ash plantations in Ontario, Canada to compare the response of the emerald ash borer (EAB), Agrilus planipennis, to (Z)‐3‐hexenol (Z3‐6:OH) and manuka oil. In the first experiment, Z3‐6:OH (7.6 mg/day) in purple prism traps hung 1.5 m above ground caught significantly more EAB than the unbaited controls, with male catches significantly greater than female catches at two locations. Manuka oil (50 mg/day) attracted equal numbers of males and females but they were significantly greater than the controls at only one location. Adding (Z)‐3‐hexenal or (Z)‐3‐hexenyl acetate in binary or ternary combinations with Z3‐6:OH did not enhance trap catch. In the second experiment, Z3‐6:OH released at two rates (7.6 or 80 mg/day) in light green prism traps placed in the ash canopy also caught significantly more males than females and more males than the unbaited controls or manuka oil‐baited traps. Manuka oil had no significant effect on catches relative to the controls. Combining Z3‐6:OH with manuka oil did not enhance catches of EAB. We conclude that there was a strong male‐biased EAB response to Z3‐6:OH lures, whereas manuka oil, when effective, attracted both sexes equally. Z3‐6:OH in light green prism traps in the canopy is an effective lure for EAB, particularly for males.

Analyses of the elytral hydrocarbons from male and female emerald ash borer, Agrilus planipennis Fairmaire, that were freshly emerged vs. sexually mature (>10 days old) revealed a female-specific compound, 9-methyl-pentacosane (9-Me-C(25)), only present in sexually mature females. This material was synthesized by the Wittig reaction of 2-decanone with (n-hexadecyl)-triphenylphosphonium bromide followed by catalytic reduction to yield racemic 9-Me C(25), which matched the natural compound by gas chromatography/mass spectrometry (retention time and EI mass spectrum). In field bioassays with freeze-killed sexually mature A. planipennis females, feral males spent significantly more time in contact and attempting copulation with unwashed females than with females that had been washed in n-hexane to remove the cuticular lipids. Hexane-washed females to which 9-Me-C(25) had been reapplied elicited similar contact time and percentage of time attempting copulation as unwashed females, indicating that 9-methyl-pentacosane is a contact sex pheromone component of A. planipennis. This is the first contact sex pheromone identified in the Buprestidae.