Pentane extracts of matureDrosophila melanogaster males substantially increased the attractiveness of food odors to both males and females in a wind-tunnel olfactometer. Extracts of females caused no such increase. An active component of the extract was isolated and identified as (Z)-11-octadecenyl acetate (cis-vaccenyl acetate, cVA), and synthetic cVA was active in bioassay. Hydrolysis of the ester linkage or movement of the double bond to the 9 position destroyed the activity. Mature virgin males released cVA into their feeding vials, and amounts of synthetic CVA equal to that released per male caused significant bioassay responses. Females, which were known to receive cVA from males during copulation, were found to emit relatively large amounts of the ester into their feeding vials within 6 hr after mating. cVA had been demonstrated previously to be a close-range pheromone inD. melanogaster, discouraging males from courting other males or recently mated females; it now appears to have a longer-range function as well.

No abstract

The leaf beetle Diorhabda elongata Brullé (Coleoptera: Chrysomelidae) has been introduced as a biological control agent for saltcedars, Tamarix spp., an exotic, invasive weedy tree in the western United State. Gas chromatographic (GC) analysis of volatiles collected from feeding male or female beetles, or saltcedar foliage alone, showed two components produced almost exclusively by males. These compounds elicited responses from antennae of male and female beetles in GC-electroantennographic detection (EAD) analyses. The compounds were identified as (2E,4Z)-2,4-heptadienal (1) and (2E,4Z)-2,4-heptadien-1-ol (2) by GC-mass spectrometry (MS), and confirmed with authentic standards. The two compounds were also detected at trace levels from feeding females and foliage controls, but the amounts from feeding males were 8-40 times higher, typically 55-125 ng per day per male. The amounts of 1 and 2 in collections from females did not differ significantly from amounts collected from control foliage. In field trials, 2 as a single component was as attractive as a 1:1 blend of 1 and 2. Compound 1 as a single component was more attractive than controls, but much less attractive than 2 or the blend. Males and females were attracted in about equal numbers, indicating that this is an aggregation pheromone.

Solid-phase microextraction (SPME) is a versatile new technique for collecting headspace volatiles prior to GC analysis. The commercial availability of uniform SPME fibers makes routine, practical quantitation of headspace concentrations possible, but straightforward information for relating GC peak areas from SPME analyses to headspace concentrations has not been available. The calibration factors (amount absorbed by the fiber divided by headspace concentration) were determined for 71 compounds using SPME fibers with a 100 μm poly(dimethylsiloxane) coating. The compounds ranged from 1 to 16 carbons in size and included a variety of functional groups. Calibration factors varied widely, being 7000 times higher for tetradecane than for acetaldehyde. Most compounds with a Kovats retention index of <1300 on a nonpolar GC column (DB-1) equilibrated with the fiber in 30 min or less. A regression model is presented for predicting the calibration factor from GC retention index, temperature, and analyte functional class. The calibration factor increased with retention index but decreased with increasing sampling temperature. For a given retention index, polar compounds such as amines and alcohols were absorbed by the fibers in greater amounts than were hydrocarbons. Henry's law constants determined using SPME were in general agreement with literature values, which supported the accuracy of the measured calibration factors. An unexpected concentration dependence of calibration factors was noted, especially for nitrogen-containing and hydroxy compounds; calibration factors were relatively higher (the SPME fiber was more sensitive) at the lower analyte concentrations.

It was previously reported that males of the crucifer flea beetle, Phyllotreta cruciferae, feeding on host foliage are attractive to both males and females in the field. Based on this evidence for an aggregation pheromone, volatiles were collected from male and female P. cruciferae feeding on cabbage (Brassica oleracea) and analyzed. For comparison, volatiles were also collected from males and females of three other flea beetle species, Aphthona flava, A. czwalinae, and A. cyparissiae, all feeding on their host, leafy spurge foliage (Euphorbia esula). Six male-specific compounds were isolated from P. cruciferae, and the same compounds plus two additional ones were isolated from males of Aphthona flava, A. czwalinae, and A. cyparissiae. The blends of compounds were relatively consistent within species, but there were characteristic differences between species. Compound structures were studied by mass spectrometry, NMR spectroscopy, UV spectroscopy, polarimetry, chiral and achiral gas chromatography, molecular modeling, and microchemical tests. Three of the compounds were identified as (+)-ar-himachalene; (+)-trans-alpha-himachalene; (+)-y-cadinene. Two others were new enantiomers of himachalene hydrocarbons that were previously identified from the fir trees, Abies alba and Abies nordmanniana. Finally, there were two himachalene alcohols and one norsesquiterpene ketone that is a himachalene analog. Only (+)-ar-himachalene and (+)-y-cadinene are previously known natural products. Electrophysiological activity was demonstrated for five of the compounds. The chemical and electrophysiological patterns are consistent with, but do not prove, a pheromonal function.

No abstract

The macrocyclic lactone (3Z)-dodecen-12-olide was identified from the emissions of the emerald ash borer, Agrilus planipennis, feeding on ash foliage. The compound was detected from both sexes but was ca. 10 times more abundant from females. It was readily sensed by antennae of both males and females. Identification was confirmed by synthesis. The behavioral effects of the lactone remain unstudied in A. planipennis, but a verified pheromonal function could lead to improved monitoring for this invasive pest. The lactone is part of the pheromone of Cryptolestes pusillus, an unrelated beetle species.

An effective synthetic attractant, based on host-related volatile compounds, was developed for the nitidulid beetle, Carpophilus davidsoni, as part of a program for managing this pest in Australian peach orchards. Fermenting peach juice and whole peaches and nectarines served as chemical models for the attractant, and synthetic formulations were sought that matched the natural sources, both with respect to emission rates of key chemicals (in ng/min) and attractiveness to flying beetles. All volatile sources were kept in airstreams during laboratory chemical measurements, and these airstreams were subsequently directed to the wind-tunnel behavioral assay, allowing the determined emission rates of compounds to be associated with particular levels of attractiveness. Chemical sampling of airstreams was by solid-phase microextraction, and analysis was by gas chromatography and mass spectrometry. A volatile delivery system was coupled to the wind tunnel and allowed facile manipulation of natural and synthetic scents. The final blend, modeled after fermenting peach juice, contained ethanol as the main constituent and 2-methyl-1-propanol, 2-methyl-1-butanol, 3-methyl-1-butanol, acetaldehyde, and ethyl acetate as minor constituents, all in water solution. Blend components were synergistic, and use of a mixture was essential for optimal attractiveness. The synthetic blend was highly effective in the field and is intended to replace fermenting peach juice and overripe peaches, which were previously used as synergists of the Carpophilus spp. aggregation pheromones in attract-and-kill stations.